MES in Vehicle Manufacturing

MES in Vehicle Manufacturing
By Tallrain
tallrain@gmail.com
Jan 2022

Table of Contents
Part A – Building Process ....................................................................5
A1 - Process of building a passenger car ....................................................................... 5
A2 - Building Commercial Vehicle .................................................................................. 9
A3 - Process of building an engine ................................................................................11
Part B – Business Requirement.........................................................13
B1 - Punch & PMC ........................................................................................................13
B2 - Welding & Order Release ......................................................................................16
B3 - Vehicle Identification..............................................................................................19
1. Ultra High Frequency RFID TAG......................................................................19
2. High Frequency RFID TAG ..............................................................................21
3. Screw/Bolt RFID TAG ......................................................................................21
4. Metal 2D barcode.............................................................................................22
5. Barcode label...................................................................................................22
B4 - Quality Management..............................................................................................24
1. Defect management.........................................................................................24
2. Quality route.....................................................................................................25
3. Quality Gate.....................................................................................................26
B5 - Route Control.........................................................................................................28
1. WBS Route ......................................................................................................28
2. PBS Route .......................................................................................................28
3. Safe Door Control ............................................................................................30
B6 - Broadcasting..........................................................................................................31
1. Lift on at engine sub-assembly lines.................................................................31
2. Process parameters preparation ......................................................................32
3. Assembly sheet printing ...................................................................................32
4. Material Pull .....................................................................................................33
5. Material back flush ...........................................................................................34
B7 - Traceability ............................................................................................................35
1. Real case of callback process..........................................................................35
2. Usage of metal 2D barcode..............................................................................36

3. Link of VIN number and engine number ...........................................................36
4. Software management .....................................................................................37
B8 - Position Calculation ...............................................................................................38
1. Encoder............................................................................................................38
2. Sensor .............................................................................................................38
3. Application example .........................................................................................39
B9 - Torque Error Proofing ............................................................................................41
B10 - Part Picking Error Proofing...................................................................................43
B11 - Error Proofing of Marking, Filling, and Gluing.......................................................46
1. Marking Error Proofing .....................................................................................46
2. Filling Error Proofing ........................................................................................47
3. Gluing Error Proofing........................................................................................48
B12 - Software Download..............................................................................................49
B13 - Andon Calls .........................................................................................................51
1. Call...................................................................................................................51
2. Notifications .....................................................................................................51
3. Escalation ........................................................................................................52
4. Line stop management.....................................................................................52
5. Shift management............................................................................................53
Part C – System Architecture.............................................................54
C1 - Basic Architecture..................................................................................................54
C2 - Introduction of Kepware OPC ................................................................................57
1. What’s OPC .....................................................................................................57
2. DataLogger ......................................................................................................58
3. ODBC Driver....................................................................................................59
4. Advanced Tags ................................................................................................59
5. IoT Gateway.....................................................................................................59
C3 - Usage of IT PLC....................................................................................................61
C4 - Soft Coupling.........................................................................................................63
Case 1: cache data with barcode labels .................................................................63
Case 2: cache data with RFID Tag.........................................................................64
Case 3: cache data in IT PLC.................................................................................65
C5 - MES-PLC Handshaking Methods ..........................................................................67

Method1: repeatedly collect data............................................................................67
Method 2: triggered by conditions...........................................................................67
Method 3: request-response mechanism, with 1 handshaking ...............................68
Method 4: request-response mechanism, with 2 handshaking ...............................68
Method 5: based on manufacturing process...........................................................69
C6 - Journey of a bolt ....................................................................................................71
1. Material delivery...............................................................................................71
2. Assembly .........................................................................................................72
3. Material Pull .....................................................................................................72
Part D – Project Management.............................................................74
D1 - Communication management ................................................................................74
1. Challenge 1: how to understand business?......................................................75
2. Challenge 2: how to align business? ................................................................75
D2 - Planning ................................................................................................................77
1. Milestones........................................................................................................77
2. Develop pattern................................................................................................77
3. Equipment Debugging......................................................................................78

Part A – Building Process
A1 - Process of building a passenger car
Normally passenger cars include family car, SUV and MPV.
Car body is the main frame of a car, is welded by steel plates, and then chassis, engine,
transmission, interior are assembled into car body. The car body is welded into a cage form,
to expand car space and reduce impact from outside damage.
The building process of a passenger car has 4 parts: punching, welding, painting, and
assembly.
3D CAD software is used to design car body, and the 3D model is also used to design
metal sheet and fixtures.
In welding process, process engineer will use 3D CAD model to design punching
fixtures. The punch machine will setup fixtures and load rolls of metal sheet, and output
component sheet according to the fixture. In punch shop, MES key function is to monitor real
time status of devices, because its availability decides whole operation efficiency.
In welding process, robots will weld component sheet into car body. The welding quality
has big impact to vehicle safety. The professional software is used to measure the gap
between designed welding points and actual welding points. The welded car body will be
transferred to WBS(Welded Body Store).
The key operations of welding:
1) Welding engine cabinet, front floor, back floor.
2) Weld these 3 parts into car frame.
3) Weld left side and right side.
4) Weld left/right sides into car frame.
5) Weld doors.
Below diagram shows key components of car body:

Diagram 1.1-1: key components of car body
Below diagram shows key welding process:
Diagram 1.1-2: key welding process
In Weld shop, MES key functions is to download Orders to Lift-on stations, such as
Engine cabinet, front floor, back floor, left side, right side. MES downloads Sales Orders from
ERP, then generate Work Orders, and then sequence Work Orders, then downloads to
Back floor sub-
assembly
Main line
Front floor sub-
assembly
Engine cabinet
sub-assembly
Floor line
Left side sub-assembly
Adjust line WBS
Right back door Right front door
Left back door Left front door
Right side sub-assembly

machine PLCs. Machines/robots will build car components based on model type and Order
attributes stored in PLC.
In painting process, a car body will take bottom painting, middle painting, top painting,
and heating operations. Most operations will be operated by machines. The painted bodies
will be transferred to PBS(Painted Body Store).
Painting shop has lots of process segments, most of them will be done by machines
automatically, and can also be repaired by manually. MES together with PLC can deliver
cars to repair areas automatically.
Below diagram shows key painting process:
Diagram 1.1-3: key painting process
In final assembly, car needs to install Trim, Chassis and all other components, and will
run test.
Key process includes:
1) Transfer vehicle from PBS based on route rules.
2) In front trim line, install passenger cabinet parts, dashboard, sunroof.
3) In chassis line, install chassis, engine, transmission.
4) In back trim line, install tires, chairs, doors.
5) In final line, install accessories, fill liquids, take visual inspection.
6) In test line, write software, and test wheel positioning, lamps, gas.
7) Building in sub-assembly lines such as doors, dashboard, engine.
In final assembly shop, most parts are assembled by manually, it relates delivery of lots
of materials. MES key functions include: assembly instruction, error proofing, material pull,
equipment integration.

Below diagram shows key process of final assembly:
Diagram 1.1-4: key process of final assembly
Below diagram shows over all process of a car plant:
Diagram 1.1-5: over all process of a car plant

A2 - Building Commercial Vehicle
Commercial vehicle include truck and bus.
Commercial vehicle uses chassis to support its weight, while it’s body in case of
passenger car.
The high level building process of a commercial vehicle includes: punching & welding &
painting of body, punching & riveting & painting of chassis, and final assembly.
The features of commercial vehicle plant are: less annual production output, longer cycle
time of each station, larger station distance, and lower requirement of automation and just-in-
time.
Commercial vehicles especially trucks have very long service time and very big driving
distance, so they have very high requirement of durability for key parts. So riveting is used
for assembly of chassis, and it’s highly controlled for tighten parts.
Key functions of final assembly shop:
1) PBS – Painted body store;
2) Vehicle location monitoring and broadcasting;
3) Assembly sheet printing;
4) Work instruction;
5) Traceability of key parts;
6) Error proofing of key parts;
7) Quality and defect management.
Diagram 1.2-1 shows main process of final assembly:

Diagram 1.2-1: main process of final assembly
Diagram 1.2-2 shows overall process of building a commercial vehicle:
Diagram 1.2-2: overall process of building a commercial vehicle

A3 - Process of building an engine
The building of an engine includes 3 processes: machining, assembly, test.
In machining shop, there’re operations of cylinder body, cylinder head, crankshaft.
Numerical controlled work centers are used to cut metal pieces into target components.
The key functions of MES in machining shop:
1) Traceability of raw parts serial number and lot number.
2) Monitoring of machine status.
3) Monitoring of key process parameters.
4) Data collection of key test result such as of leak test.
5) Scrap management.
System is not required to manage orders.
Monitoring device status can act quickly to abnormal situations.
The traceability of raw parts and key process parameters, is very helpful while it’s
required to call back products by batch.
Key processes of assembly shop:
1) Cylinder head sub-assembly.
2) Piston sub-assembly.
3) Interior assembly.
4) Exterior assembly.
5) Cold test – test without starting up engine.
Assembly shop is managed by scheduled orders. If production line supports multiple
models, then it also requires just-in-time material handling. And the most important stations
are assembly stations and torque stations.
The key functions of MES:
1) Release orders to lift-on stations.
2) Material error proofing.
3) Key parts traceability.

4) Torque error proofing.
5) Travel record and broadcast, and interface for material handling.
6) Device monitoring.
7) Quality call.
8) Quality defect management.
9) Data collection of gap detection and cold test.
Hot test means to start up engine, and simulate real working situation and worst
conditions, and record the running data.
Hot test usually uses custom test stations and software, and MES collects test data via
interface.
Diagram 1.3-1 shows key process of engine plant:
Diagram 1.3-1: key process of engine plant

Part B – Business Requirement
B1 - Punch & PMC
Building a vehicle requires lots of money.
To develop a new type of vehicle, almost needs 500 million RMB for development and 2
billion RMB for manufacturing.
Development cost include: model design, prototyping, process design, component
design, vehicle calibration, vehicle testing, component testing.
Manufacturing cost include: facility building, device buying and setup, production
preparation.
During manufacturing cost, device buying and setup take almost 3/4, and Punch Shop
takes 35% of device cost in whole plant.
Suppose one type of vehicle is very welcomed by customers, its sales number is beyond
plant’s building capacity, in that case, is it possible to expand plant and buy more devices to
build more vehicles?
From point of view of Punch Shop, it’s very difficult.
Because punch machine has very high requirement to ground flatness and stability, so
it’ll take very long time to build punch facility. Besides that, punch models also need long time
to build.
So in order to improve plant capacity, it’s most likely to use current devices effectively as
possible.
Punch process includes: Unpack, get material, transfer material, positioning, feed
material, cleaning, punch, test. Most processes are done by punch machine automatically,
operators assist machine accordingly.
So, production and devices and systems need to support devices:
- Operators need to assist devices to ensure daily work continuously.

- Device engineers need to maintain devices, and fix problems ASAP.
- Systems need to find out any errors or alerts, and to notify engineers accordingly.
So in Punch Shop, the main functions of MES is PMC.
PMS is short of Production Monitoring and Control, in MES field, it’s focus on devices.
PMC collects below information:
1) Devices’ running state.
2) Device abnormal information, such as alert code, error code.
3) Number counters, such as shift production counter, buffer zone counter.
4) Time counters, such as accumulated down time.
5) Devices’ key process parameters.
6) Working-in-process product information, such as serial number, material number, model
type.
7) Production rate information, such as assembly time, waiting time, blocked time.
8) Line speed.
Technically speaking, MES is mainly collecting device data via PLC.
PLC is short of Programmable Logic Controller, is the logic layer and application
interface of devices.
PLC stores PMC related business data into specific Data Blocks, and then MES get data
from PLC via OPC.
OPC is short of OLE for Process Control, can map PLC data into OPC Server memory
tags. MES communicates with OPC via OPC client or IIoT gateway. Below diagram shows
PMC data flow:

Diagram 2.1-1: PMC Data Flow
We can see that, after OPC collected devices data from PLC, it uses data for 2 purpose:
1) OPC sends data to SCADA Server, and then output data in real time via SCADA client.
2) OPC sends data to MES Server, archives in Database, then outputs as report.
In lineside, operators and engineers are checking real time data.
SCADA is short of Supervisory Control And Data Acquisition. Production department can
monitor and control devices remotely, and IT uses SCADA for collecting and displaying data.
Popular SCADA products include: Siemens WinCC, Rockwell FTView, GE Cimplicity.
SCADA server can synchronize data from OPC server quickly, its rate frequency is
250ms~1000ms, and then SCADA client gets data from SCADA Server, and then output
data into TV or LED board.

B2 - Welding & Order Release
Normally vehicle manufacturing is scheduled by Work Orders.
There’s a term OTD(Order To Delivery), means the whole process from creating Sales
Order to delivering product.
Based on customer request, market investigation and forecast, shop dealer create Sales
Order in car maker’s sales system.
Sales system will bind the information with market strategy, then release Sales Order.
Then Sales Order is loaded into plant’s ERP system, which will check with plant
calendar/machine status/material storage/purchase plan, then run MRP/APS, and create
daily Work Order for it.
And then SRM system will generate component delivery request, and send it to vendors.
After vehicle is built, it will be transported to dealer.
Diagram 2.2-1 shows OTD flow:
Diagram 2.2-1: OTD flow

Normally for process of punching, welding, painting, and assembly, each process costs 1
day for manufacturing, and then costs a couple of days for transporting. ERP will base on
Sales Order to generate Work Orders of Assembly Shop, then create Work Orders of other 3
shops accordingly.
ERP Work Orders have the vehicle data such as model type, they also show the building
sequence of each day.
But in Punch Shop, because it uses batch build model, it will not follow the Work Order
sequence strictly.
In Welding Shop, MES downloads ERP Work Orders, and generate daily MES Work
Orders. In MES, planners can lock/freeze/re-sequence these Work Orders, so the final
sequence could be different than original sequence.
After completing welding, vehicles come into Paint Shop through WBS, these vehicles
can be re-sequenced according to WBS routing rules.
After complaint painting, vehicles come into Assembly Shop through PBS, based on
PBS routing rules, normally vehicles will be re-sequenced based on model type, VIN
numbers, etc.
Normally only Welding Shop’s Work Order sequence is highly aligned with ERP
planning.
In Welding Shop, MES needs to accomplish these planning functions:
1) Download Work Orders from ERP automatically.
2) Lock, freeze, re-sequence Work Orders.
3) Validate Work Order, such as to check process readiness.
4) Send Work Orders into PLCs of main line and sub-assembly lines.
5) Broadcast Work Orders to later stations.
As showed in diagram 2.2-2:
1) MES releases Orders into stations of Front Floor, Back Floor, Front Cabinet, and
SL010/SR010/SL070/SR070 of Main line.
2) In UB010 merge station, PLC will check if the components from 3 sub-assembly are
matched, if so then generate VIN number for it.
3) When vehicle comes to main line, PLC will check if it matches with components from sub-
assembly lines, if not then get component from buffer zone.

Diagram2.2-2: Order release in Welding Shop
At Work Order downloading stations, device PLC downloads Work Order data from
MES, including: Sales Order, Work Order, VIN number, model type, vehicle attributes, etc.
The key data will be written into RFID Tag in merging station.
As off-line buffer, normally PLC will buffer Order data of 3~10 vehicles.

B3 - Vehicle Identification
This article introduces the methods of identifying vehicles during manufacturing.
There’re 5 types of material used to identify vehicles:
1) Ultra high frequency RFID Tag, mostly used in vehicle manufacturing.
2) High frequency RFID Tag, mostly used in manufacturing of engine and transmission.
3) Screw/Bolt RFID Tag, mostly used in machining of engine and transmission.
4) Metal 2D barcode, mostly used in machining of engine and transmission.
5) Paper barcode label, mostly used in vehicle manufacturing.
Details are mentioned as below.
1. Ultra High Frequency RFID TAG
Ultra High Frequency RFID Tag is referring to RFID Tag which works in frequency range
of: 65 - 868 MHz(Europe), and 902 - 928 MHz(North America).
RFID is short of Radio Frequency Identification.
Tag is the material used to store data.
RFID related devices include:
1) Tag, used to store data.
2) Antenna, used to expand covering area of radio frequency signal.
3) Reader, used to write data to Tag, and read data from Tag, and send energy to activate
Tag.
4) Communication module, used to transfer data between Tag and PLC data block.
5) PLC or PC as data receiver.
6) Other devices, such as cable, connector.
Diagram 2.3-1 shows relationship between RFID related devices:

Diagram 2.3-1: Relationship of RFID related devices
The advantage of Ultra High Frequency RFID is its high range of identification area,
which can reach a couple of meters.
In vehicle assembly shop, a typical station has 6 meters, and vehicle is moving slowly
during reading, Ultra High Frequency RFID can support such requirement from distance and
angle.
Now let me introduce some working scenarios.
Scenario 1: Merge station of Welding Shop
When vehicle’s sub-assembled parts come from Front Cabinet/Front Floor/End Floor,
and move forward into merge station, PLC will download new Work Order and VIN number of
new vehicle, together with information such as model type, color, vehicle attributes, and then
PLC writes data into RFID Tag.
Scenario 2: Quality Check station

There will be a RFID station before Quality Check, and another RFID station after
Quality Check, after receiving data from PLC and RFID Tag, MES will know the vehicle list
which have already passed previous RFID station, but not yet passed later RFID station, so
in Quality Check station, MES will display this list, and operator can pick one from it.
Scenario 3:: Material trigger station in Assembly Shop
Normally there will be a RFID station in PBS OUT, so when vehicle passed this station,
MES will broadcast vehicle number to logistics handling/execution system, to trigger the pull
of material for assembly lines.
2. High Frequency RFID TAG
High frequency RFID works in 13.56 MHz, its read/write distance is less than 0.2 meter.
Due to this limitation, the application of RFID should match with below conditions:
1) Tag should be holding still during reading/writing.
2) Tag should be near Reader as close as possible.
Such technology is used in assembly of engine and transmission quite a lot, because
their manufacturing process can match with these 2 conditions.
For example, when the engine comes to an assembly station, it will be holding still on
the pallet, and RFID Reader is installed just below pallet, and RFID Tag is plugged into pallet
just above Reader.
The feature of this type of RFID makes it quite different to identify an engine than the
way to identify a vehicle.
1) Uses High Frequency RFID.
2) A Reader is installed in each station, while in vehicle assembly Readers are only installed
in line head and line end stations.
Since each station has installed RFID Reader, it’s reasonable to store process data into
RFID Tag as much as possible, so we can read and write RFID Tag directly, without
interacting with MES for each station.
For example, Siemens High Frequency RFID Tag can store up to 54KB data, then we
can store lots of data into it, such as product master data, lift on data, BOM, key working
command, key process parameters, assembled part Serial Numbers, traceability data, repair
data, so a Tag can be regarded as a working manual and also as an assembly dataset.
3. Screw/Bolt RFID TAG
The key part of an RFID Tag is its data storage chip, which can be packed and installed
with many ways.

Some Tags are packed with magnet together, so we can stick it at top of vehicle; So
Tags are packed as coin-thick plate, so we can plug it into pallet.
Here introduces screw form Tag, such as Siemens RF630T, this Tag is packed with a
M6 screw and a 64B data chip, can be installed into M6 holes. Balluff’s screw form RFID Tag
can store data up to 64KB.
This kind of Tag can be used in 2 typical scenarios.
Scenario 1: machining of engine and transmission.
In Machining Shop, we don’t have pallet, the mechanical parts are moved between
stations by robots, so we can only install Tag into mechanical parts, and move together with
it.
Scenario 2: Assembly of engine and transmission.
Although we do have pallet in assembly, but some company want to keep key
manufacturing data in RFID Tag, and ship it to customers as part of product, so in the future
if we need to repair it, we can read original manufacturing data from RFID Tag.
4. Metal 2D barcode
In machining shop of engine and transmission, to avoid infection of bad environment,
normally laser marking is used to generate 2D barcode in surface of metal part.
The machine used to generate metal 2D barcode is called laser marker, it consists of
laser transmitter, control module, positioning module, communication module.
Metal 2D barcode cannot be identified by normal handhold barcode scanner, it needs
specific device for identification, it consists of photo taking, image processing, OCR, and
communication modules.
5. Barcode label
Barcode labels have been used in MES field all the time, especially in vehicle
manufacturing.
Barcode labels have these outstanding advantages:
1) Very cheap.
2) Can be read by man eyes.
3) Don’t require interaction with backend system(PC regards scanner as keyboard device).
Now let me introduce 2 typical scenarios.
Scenario 1: Assembly sheet printing

When vehicle passed through PBS, MES will trigger all sub-assembly line printers to
print out assembly sheet of each line, the sheet includes lots of barcode labels, such as of
VIN number, model type, key station part numbers. When vehicle comes to assembly station,
operator will scan labels of part on stack, and also of label of part in sheet, then MES will
validate if they are matched or not.
Scenario 2: Error Proofing.
When a vehicle is started assembly, MES will print out an Error Proofing sheet, which is
a list of barcode labels, each label is the parameter string of each key Error Proofing station.
When vehicle comes to Error Proofing station, operator scans Error Proofing label, and then
device PLC gets parameters from label.

B4 - Quality Management
Quality management is a key function of MES.
This article will introduce some specific functions of quality management in vehicle
manufacturing.
1. Defect management
In quality management module, defects are configured as master data.
Scientific definition of defects helps operators to input defects quickly, and it also helps
to generate defect analysis report with more values.
Here introduces 2 types of defect definition.
Type 1: grouped by class, such as class level 1/class level2/defect, or
shop/line/station/defect.
Type 2: grouped by coordinates. For quality check station, we can load a component
picture into system, and system will split it into lots of areas with horizontal and vertical
coordinates. When defects are found, operator click the according position of the picture,
then MES will find its mapped coordinate and store it into system.
Type 2 is mostly used for appearance check.
Based on the data recorded by coordinates, MES can generate report to highlight the
defect density of each area, and then we can adjust our process to improve quality
accordingly.

Diagram 2.4-1: Input defect based on coordinates
2. Quality route
In vehicle manufacturing, MES is highly integrated with automation systems, even the
manual quality check result should interact with conveyor line.
The so-called quality route means to decide vehicle’s route based on quality status. Here
we have 3 scenarios.
scenario 1: vehicle quality route.
As shown in diagram 2.4-2:
1) When vehicle comes to quality check station, operator input defect, and then choose a
repair lane, the data will be saved into MES. If no defect found, then vehicle will be marked
with default lane.
2) When vehicle comes to turn table, PLC identifies vehicle, and then request to get lane
number from MES, and then transfer vehicle accordingly: via default lane to next station,
or via repair lane to repair area.
Diagram 2.4-2: Vehicle quality route

Scenario 2: engine quality route.
Consider that engine is standing still in any assembly station, so we can install RFID
reader in any key assembly stations and turn tables.
So in any assembly station or quality check station, operator can input defects, and PLC
will write quality status and route number into RFID Tag; when vehicle comes to turn table,
PLC reads route number from RFID Tag, and then move engine forward accordingly.
Scenario: product audit.
Normally for audit, we pick audit target based on specific rate, and we don’t want
operators to know whether a product requires audit or not.
So, based on audit rate, we can decide which product require audit when generating
Work Orders, and write the audit mark into RFID Tag.
When vehicle comes to turn table before audit, PLC reads audit mark from RFID Tag,
and then move vehicle accordingly.
3. Quality Gate
Normally we setup Quality Gate after a set of key manufacturing process, such as
vehicle’s lift off station of welding/painting/final assembly, and engine’s lift off station of inner
line/outer line.
From point of view of quality control, Quality Gate will check if a product has completed
process of current area, if yes then allow it to move forward to next process.
Quality Gate will check below quality data if possible:
1) If quality status is good.
2) If completed all key stations.
3) If short build or over build any component.
4) If failed in any test stations.
5) If failed in any audit station.
6) If any defect not cleared.
Based on the check result of Quality Gate, MES will work with PLC, to decide vehicle’s
direction, for example: lift up Gate bar so vehicle can drive to parking lot, or lock Gate bar
and alarm operator to drive vehicle back to repair area. Its logic is:
1) PLC identify vehicle by RFID.
2) MES check its quality result, and show it together with defects(if have) in TV.
3) MES transfers quality status to PLC, PLC turn on traffic light, and lift up or lock the Gate
bar accordingly.
Refer to diagram 2.4-3.

Diagram 2.4-3: Quality Gate and Quality bar

B5 - Route Control
Route Control means based on MES commands, conveyor PLC will decide how to move
vehicle forward.
This article will introduce some key route control functions.
1. WBS Route
Vehicle manufacturing has 4 key process: Punch, Welding, Painting, Final Assembly.
There’s a WBS buffer zone between Welding Shop and Painting Shop, and a PBS buffer
zone between Painting Shop and Final Assembly Shop.
WBS is short of Welded Body Store.
PBS is short of Painted Body Store.
With some painting conditions, if we need to change painting color for next vehicle, then
we need to stop machine, and clean, and change oil for it, it will take quite a lot of time. So to
reduce machine shut down time and the waste of oil, normally we will schedule the vehicles
by same color.
So in WBS area, MES will re-sequence the vehicles by color.
Besides of that, WBS also has functions of:
1) Offers a big buffer zone.
2) Offers a return lane, to return vehicles back to repair.
3) Track vehicle location based on RFID identification.
2. PBS Route
PBS locates between Painting Shop and Final Assembly Shop.
The setup of PBS is based on these requirements:
1) Planners want to align Work Order to Sales Orders.
2) Logistics handlers want some parts delivered by batch in sequence.

3) Production department want to build some model for quite a long time, to reduce operation
mistakes.
4) Process department want to balance the lines so workers won’t be tired very soon.
Normally PBS route function is consisted of MES/PLC/HMI/RFID devices, and can be
achieved by different methods, such as:
1) MES sends route command by rules automatically..
2) PLC routes by rules automatically.
3) Operators handles by HMI manually.
Diagram 2.5-1 shows an example of PBS route, icon of R stands for an RFID read
station:
1) Vehicle leaves Painting Shop, MES collects its travel record, and broadcasts to ERP for
back flush.
2) Vehicle comes to PBS In, MES informs conveyor PLC with lane number. Route rule: based
on vehicle model.
3) PBS area has a fast lane, 1 return lane, and 4 normal lane. Fast lane is controlled by
manually, which allows vehicle come to PBS out directly. Return lane is also controlled by
manually, which is used to hold specific vehicles.
4) MES offers route rules such as by minimum VIN number and by model, and informs PLC
to move vehicle based on rule. Fox example for minimum VIN number rule, MES will check
the minimum VIN of all 4 lanes, and inform PLC to move that vehicle of according lane.
5) Vehicle leaves PBS, and moves along conveyor line, and comes to tear-off-door station,
so there’s a sequenced vehicles buffer between PBS Out and tear-off-door station.
Diagram 2.5-1: PBS Route

3. Safe Door Control
I’ve introduced Quality Gate in previous article, which controls vehicle moving by using
block bar and traffic light.
The same method is also used in Final Assembly Shop, diagram 2.5-2 shows a safe
door control process after completing assembly.
1) After completed all assembly, and validated quality good, then vehicle will be driven
through Door #1 or #2, forward to Logistics Parking Lot, there the vehicle will be handled
by 3rd party company to deliver to car dealer.
2) If a vehicle needs road test, then it will be driven through Door #3, and return back to Final
Assembly Shop through Door #4 after test.
3) If a vehicle needs process hold(holding for some time for further quality check), then it will
be driven to Process Parking Lot through Door #5, and then drive out through Door #6.
4) Any vehicle with issues found will be driven back to Repair Area through Door #7.
Diagram 2.5-2: Safe Door control process

B6 - Broadcasting
Vehicle manufacturing is very complicated, it has lot of processes, and lots of them are
interactive from each other.
For automation design, it requires lots of data exchange between different
stations/areas/devices/lines, normally it’s via point-to-point communication between PLCs.
And MES as a system covering whole plant/most process/most devices, normally it will
be acting as backbone of data exchange of most data.
This article will introduce some cases.
1. Lift on at engine sub-assembly lines
The engine assembly consists of 4 assembly lines: interior line, exterior line, cylinder
head sub-assembly line, and piston sub-assembly line. Interior line and exterior line are
working one after another, and the 2 sub-assembly lines are quite independent.
To work as per Orders, we need to align sequence of sub-assembly lines with main
lines.
This is the way to do it:
1) When MES receives Work Orders from ERP, it will generate sub-orders of sub-assembly
lines.
2) When engine is lift on at interior line head station, MES will broadcast information to head
stations of sub-assembly lines: with Work Order, Engine number, part number, engine
model.
3) Sub-assembly lines will lift on based on the data it received.
Please refer to diagram 2.6-1:

Diagram 2.6-1: Engine lift-on broadcast
2. Process parameters preparation
Now most vehicles plants and engine plants require flexible production, that means
same line and same devices can support manufacturing of multiple model types.
This requires line-side devices can work flexibly, can work based on process
parameters and profiles automatically.
To make sure daily work continuously, MES is required to broadcast related data to
line-side devices.
For example in vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES
will broadcast these information:
1) Sends VIN marking data to interior line PLC, and VIN marking system of engine line.
2) Sends VIN number and model type to Torque Gun system; later when vehicle comes
to torque station, Torque Gun system sends torque program to torque controller.
3) Sends VIN number, model type, attributes, software BOM to vehicle calibration system;
later when vehicle comes to working station, calibration system write software to
vehicle ECU.
4) Sends VIN number, model type, attributes to vehicle test system; later when vehicle
comes to working station, test system will run test programs with according
parameters, to check wheels and lamps and other functions.
3. Assembly sheet printing
In vehicle’s Final Assembly Shop, when vehicle leaves PBS out, MES will command
printers of sub-assembly lines, to print out assembly sheets.

Assembly sheets are normally A3 or A4 papers, include such information:
1) Vehicle’s basic data such as VIN number, model type, attributes, color.
2) Part number, part description, and part barcode label of key parts. Barcode labels are used
for error proofing: at key part error proofing stations, worker will scan VIN number, then
barcode labels of assembly sheet, then scan vendor’s labels, then MES will check if
vendor’s labels are matched with part labels of assembly sheet, if not then raise error.
4. Material Pull
In vehicle Final Assembly Shop, daily production follow JIT(Just In Time) rules, to make
sure production is as effective as possible.
Line’s capacity is limited by capacity of workers and machines, the other
operations(such as material handling, machine readiness) are supporting them.
The requirement for material handle:
1) Only store necessary materials to avoid wrong usage.
2) In case of material shortage, requires supply in time.
Diagram 2.6-2 shows relationship between MES and material handling:
1) When vehicle travels through key material pull station(such as PBS out, and interior line
head), MES will generate vehicle’s travel request based on RFID data, and broadcast to
LES(Logistics Execution System).
2) When LES receives broadcast data, it will cut down storage of line-side material, as they
are considered to be consumed soon, and check if it’s smaller than safe storage, if so then
trigger a material pull request.
3) Material handlers will get material from buffer zone or warehouse, and then deliver to
assembly line.

Diagram 2.6-2: MES and material handling
5. Material back flush
MES will offer an interface, to broadcast back flush data to ERP.
When vehicle comes out of Welding Shop, Painting Shop, Final Assembly Shop, MES
will send out broadcast of VIN number, then ERP will back flash materials of that vehicle.

B7 - Traceability
One of vehicle’s key features which differs it from normal products is, it transports people
in public area, so it’s absolutely important to consider its safety.
To make sure vehicle safety, government released lots of laws and policy, among which
callback management is one key method.
To achieve callback, car makers must build relationship between vehicle and key
parts(such as engine, transmission, air bag, wheel, etc.) in MES, which is mapped as link of
VIN number and key part serial numbers. Besides that, sales system will also record link of
VIN number and customer.
So when one batch of key parts are found with quality issue, we can trace back in MES,
to get the VIN number list which are assembled with this batch of parts, and get customer list
from sales system to notify.
This article will introduce the whole process of callback, and how to do traceability in
MES with examples.
1. Real case of callback process
Takata is a famous air bag builder, but from year 2015, it is reported out serious quality
issues of its products, in some cases, expanded air bag will bring additional damage to
passenger.
So lots of vehicles assembled with these air bags are called back, detail steps are:
1) Takata queries and list out all serial numbers of air bags, and send them to car makers.
2) Car makers query and find out which vehicles have assembled with these air bags, and
also find out customer information of these vehicles, and send them to car dealers.
3) Car dealers notify customers to drive their cars to change air bags, and send new serial
number back to car maker, who will update the traceability data into their system
accordingly.

2. Usage of metal 2D barcode
Normally for vehicles, traceability of parts is done in Final Assembly Shop, by
scanning part barcode labels.
As for assembly of engine and transmission, barcode labels are also used, but for
machining, metal 2D barcode are more often used for traceability.
Due to limitation of bad environment conditions(oil/water/heat), barcode labels will
be damaged easily, then they’ll be hard to identify.
So engine maker will require vendor of raw part to mark metal 2D barcode in
outside, and after engine is lifted on, another metal 2D barcode will be marked
representing engine itself.
Marking operations are done by specific laser marking machines, and marked
barcodes are identified by specific devices, such as products of COGNEX.
For paper barcode, 1D or 2D, they are formed with square blocks; but for metal 2D
barcode, they are formed with circle pits.
The identification device is basically an image device, which take a photo, then
process image with OCR algorithm, to get valid characters from it.
Identification devices can be connected to MES clients via ports of USB or RS232,
or connect to PLC via Industrial Bus such as Profinet/Profibus, and then connect to MES
via OPC.
3. Link of VIN number and engine number
Engine is heart of a vehicle, to make sure safety of a vehicle, vehicle builder must make
sure VIN number is aligned with engine number.
Except for recording the link in Database, it’s also required to mark VIN number outside
of engine.
The detail process:
1) When vehicle comes through PBS Out, MES sends VIN number to conveyor PLC and
marking device of Engine Assembly Line, and print out assembly sheet with VIN barcode
in it.
2) In Engine Lift on station, worker scans VIN barcode of assembly sheet by sequence, then
PLC will validate it with information it received, if pass then lift on the engine.
3) In Marking station, worker scans VIN barcode, and operates Laser Marking device to mark
VIN barcode.
4) PLC writes VIN number, engine number into RFID Tag, which is plugged into engine pallet.
5) When engine pallet comes to vehicle chassis line, PLC will compare 2 VIN numbers: one
is form RFID attached to vehicle, one is from RFID of pallet. If they’re same then continue
to build.

4. Software management
Vehicle software such as ECU(Engine Control Unit) are not physical parts, so it cannot
be called back as them.
But sometimes car makers will inform customers to update software in car dealers, the
method is quite similar as callback.
For MES, software are some kind of special parts – virtual parts, which version is similar
to part’s serial number or batch number. So within vehicle’s traceability system, not only
serial numbers of physical parts are included, but also key software’s versions are recorded.
For car makers, by trace software version, they can also check if customers have
hacked software, if so then they can identify it in car deals during running diagnostic
software.

B8 - Position Calculation
In vehicle Final Assembly Shop, conveyor lines are used to move vehicles, which bring
an issue of vehicle identification.
We know that normally RFID Reader or fixed Barcode Label Scanner are installed at line
head or line end stations, because when vehicle comes into or ready to leave line, carrier of
vehicle will be standing still for a while, and we can use that period of time for vehicle
identification.
But in Final Assembly Shop, most assembly stations especially Error Proofing
stations(such as Torque Gun, Part Picking, Marking, Gluing, Filling) are in the center of line,
assembly operations are made when vehicle is moving.
In vehicle industry, we normally use Encoder and Sensor together with RFID Reader to
calculate vehicle’s real time position.
1. Encoder
The so-called Encoder is a special device which can output its speed and rotated angles
in real time.
After connecting to conveyor line, Encoder will be running with same speed as conveyor
motor, and the data of speed and angle will be integrated into conveyor PLC, and PLC will
convert them into speed and distance of conveyor line movement.
Encoder is a device with high accuracy, it also offers state(active/not-active) and
direct(clockwise/anti-clockwise), and it’s very convenient to integrate with PLC.
2. Sensor
In vehicle industry, paired through-beam Photoelectric sensors are used quite a lot. It
consists a sender and a receiver, the sender sends out a beam of light, then receiver will
check if it can receive the light in a period of time, if not, that means the light is blocked by
some object, then PLC will set a Blocked signal.

A vehicle in plant normally is loaded into a special carrier, and moving in specific
direction, when vehicle with carrier comes to specific position, it’s supposed to block sensor’s
light, we can regard sensor’s Blocked signal as vehicle in position.
3. Application example
As showed in diagram 2.8-1, conveyor PLC integrated with 1 Encoder and 4 Sensors in
this case:
Diagram 2.8-1: Conveyor and Encoder, Sensors
The functions of 4 Sensors:
1) Sensor #1 collects signal when vehicle is loaded into line. This sensor is installed at line
head station, so when vehicle comes to station, the carrier will block the light of sender.
2) Sensor #2 check whether it’s an empty carrier. This sensor is also installed at line head
station, but it has different height than sensor #1. If it’s not empty, then the body of vehicle

should block the light of sender.
3) Sensor #3 check whether carrier comes to RFID Reader, if yes then triggers RFID reading.
4) Sensor #4 check whether carrier comes to 70% position. Because in Final Assembly Shop,
all stations of same line have same station length, so when vehicle of 1st
station comes to
70% position, that means the vehicles in other stations should come to 70% position as
well. And in theory all assembly and Error Proofing operations should be done by 70%
position, and we need to use the left 30% of time to reset tools and get vehicle ready to
leave current station.
And then inside PLC we set a dataset to maintain VIN number, and conveyor position of
each vehicle:
VIN sequence VIN number Conveyor position
1 VIN1 1000
2 VIN2 7000
3 VIN3 13000
4 VIN4 19000
After a period of time, as conveyor line moves forward, its position number will increase
accordingly, so as vehicles’ position.
So by reading Encoder, we can get real time position of conveyor line, and from which
we can convert it to actual position range of each station:
Station Position range
0 0~6000
1 6000~12000
2 12000~18000
3 18000~24000
By comparing vehicle position and station position, PLC can calculate vehicle’s current
station.
For example vehicle #3 has position of 13000, which is at range of 12000~18000, which
refers to station #2.

B9 - Torque Error Proofing
In vehicle assembly and engine assembly, bolts are used quite a lot to attach 2 parts
together.
This article will use an example of engine assembly, to introduce how bolt torque
operations are integrated into Error Proofing system.
Before torque operations happen, there’re lots of work need to be done as pre-
conditions:
1) Quality department calibrate torque value of each torque gun.
2) Process engineers configure torque parameters, such as: station, torque gun number, click
number, torque angle, program code.
Torque operation system consists of: torque gun, torque controller, PLC, torque server.
Torque gun is the executor; controller is the logic controller of torque gun, and it’s also
communication layer between torque gun and PLC; PLC transfers control command and
program code; torque server is used to store historical torque values, and can also generate
torque curve for analysis.
Diagram 2.9-1 shows key process of a typical torque error proofing:
1) Engine identification: when engine comes to torque station, PLC reads engine serial
number from RFID Tag, and sends it to MES via OPC.
2) Error proofing request: MES queries torque process of this type of the engine, and get
related data such as torque gun number, click number, torque angle, program code, and
then send these data to PLC via OPC. Then PLC send torque command to torque controller.
3) Error proofing result: worker will execute torque operations based on working instruction,
robot will work based on torque command; while one click of a gun is validated, then
controller will regard it as a valid click, and update it to PLC; while a gun reached its
requested click number, then PLC will regard error proofing of this gun is passed; when all
guns passed error proofing, then PLC will regard the error proofing of this engine in this
station is successful.
4) Torque data record: torque controller will upload all torque process data to torque server,
which can generate torque curve for analysis. And controller will also send the final torque
result and torque values to MES via PLC and OPC, the data will be linked to engine number,
as part of traceability.

Diagram2.9-1: torque error proofing
This article introduced one method of torque error proofing, there’s another method
which is also quite often used: to configure click number and angle as torque profile inside
torque controller, so MES only needs to configure and transfer torque profile to controller via
PLC.

B10 - Part Picking Error Proofing
In Assembly Shop of vehicle/engine/transmission plant, there’re lots of assembly
operations, and the lineside area is crowded and flexible, which brings lots of challenges in
management:
- How to deal with situation that a worker missed one part?
- How to deal with situation that a worker picked wrong part?
- How does conveyor line know the manual operations are done, and is ready to release
from current station?
To meet these challenges, we can design a Part Picking Error Proofing module, and
integrate with automation devices via sensors and PLC.
Let’s take an example of engine plant.
Firstly we need to expand BOM.
Normally when Engineering team release a product, an Engineering BOM and a
Manufacturing BOM will be attached to the product.
Engineering BOM defines relationship between product and its semi-product and
components.
For example, product A consists of semi-product A11 and A12, which consist of
component A21, A22:
Layer Part Number Part Name Qty
0 FG20170001 Product A 1
1 SA20170011 Semi-product A11 1
2 PR20170021 Component A21 10
1 SA20170012 Semi-product A12 1
From Engineering BOM we can see the assembly relationship and quantity of each part.
But from point view of manufacturing, Engineering BOM is not detailed enough, so
normally we need to expand it to Manufacturing BOM.

Manufacturing BOM will mark assembly part as building part or buying part, and for
component, it will also mark assembly station and quantity. As showed in below table, we
can see that part A22 under A11 has been split into station 1002 and 1003 for assembly:
Layer Part
Number
Part Name Station Qty
1 SA20170011 Semi-product A11 1010 1
2 PR20170021 Component A21 1001 10
2 PR20170022 Component A22 1002 10
2 PR20170022 Component A22 1003 10
1 SA20170012 Semi-product A12 2010 1
2 PR20170021 Component A21 2001 4
2 PR20170022 Component A22 2002 6
Manufacturing BOM is detailed enough for purchasing and manual assembly, but it’s still
not good enough for Part Picking Error Proofing: we also need to know the storage location
of each part, so we need to further expand it to Process BOM:
Layer Part
Number
Part Name Station Qty Rack
Number
1 SA20170011 Semi-product A11 1010 1
2 PR20170021 Component A21 1001 10 1
2 PR20170022 Component A22 1002 10 2
2 PR20170022 Component A22 1003 10 1
1 SA20170012 Semi-product A12 2010 1
2 PR20170021 Component A21 2001 4 1
2 PR20170022 Component A22 2002 6 1
By analyzing Process BOM, MES gets the Part Picking Error Proofing request of each
station(which Stack Number and Quantity), and then transfer the request to station PLC via
OPC, so now PLC knows in this station, which part from which stack should be picked, and
how many of them is required to pick.
Then PLC will execute the detailed Error Proofing process.

We need to install additional lamp and sensors, the sensors can detect whether it’s
blocked by object in short distance, and thus send signal to PLC accordingly, as referring to
diagram 2.10-1:
Diagram 2.10-1 Part Picking Error Proofing process
The detailed process:
1) Engine comes to station, PLC reads engine number from RFID, and sends it to MES.
2) MES analyzes Process BOM and gets Part Picking Error Proofing request of this engine
in current station, and then sends the request to PLC via OPC; PLC analyzes the request
and turns on stack lamp accordingly.
3) When worker picks a part from stack, his arm blocks the sensor, so sensor sends a blocked
signal to PLC, which will be regarded as a part picking operation by PLC; when the total
picking time has reached to the number in request, PLC will regard the error proofing of
this part is completed, so it will turn off its stack lamp; when all parts have completed Part
Picking Error Proofing, PLC sends Error Proofing Completed signal to MES, and allow
engine to leave current station.

B11 - Error Proofing of Marking, Filling, and Gluing
In vehicle’s Final Assembly Shop, there’re Error Proofing requests of Marking, Filling and
Gluing, all of them have interaction with MES.
1. Marking Error Proofing
There’re 2 types of marking: plate marking, body marking.
Vehicle brand plate is a metal plate with vehicle’s basic information, such as model type,
VIN number, Engine type, weight, plant number, build date, etc. The plate is cover by a layer
of black material, and the Laser Marking machine will mark data by removing material
accordingly.
As for body marking, marking machine will mark data into surface of vehicle
body/chassis/engine/transmission.
Plate marking can be done in advance outside of line.
Body marking can only operate in lineside when vehicle comes to station.
From point of view of MES, they are very similar logically.
Marking machine is working together with a specific PC, which talks with MES to get
marking data and then sends to marking machine.
Diagram 2.11-1 shows key process of Marking Error Proofing:
Diagram 2.11-1: Marking Error Proofing

Key process:
1) When vehicle passes PBS Out, MES sends VIN number and marking data to marking PC,
and print out assembly sheet.
2) When vehicle comes to marking station, worker scans VIN number of assembly sheet,
then marking PC will valid it with its VIN sequence, if OK then find the marking data and
sends to marking machine for marking operations.
2. Filling Error Proofing
In vehicle’s Final Assembly Shop, there’re filling operations of Coolant/brake
fluid/refrigerant/oil.
Normally the filling operation is done by machine automatically, and is controlled by PLC.
So it’s quite different than marking operations.
Diagram 2.11-2 shows key process of Filling Error Proofing:
Diagram 2.11-2: Filling Error Proofing
Key Process:
1) When vehicle comes to head station of line, Error Proofing PLC reads RFID to get VIN,
then requests MES to get Filling parameters, and stores them in its Data Blocks.
2) When vehicle comes to Filling station, Error Proofing PLC sends VIN number together with
its Filling parameters to Filling device PLC, then Filling device PLC will execute Filling
operations accordingly.

3. Gluing Error Proofing
Gluing process is quite similar as Filling process, it’s also controlled by PLC in lineside.
But Gluing has a unique requirement: the whole gluing and assembly process must be
completed within specific time, otherwise the glue will be invalid and failed.
Diagram 2.11-3 shows key process of Gluing Error Proofing:
Diagram 2.11-3: Gluing Error Proofing
Key process:
1) When vehicle comes to head station of line, Error Proofing PLC reads RFID to get VIN
number, then requests MES to download Gluing parameters, and then stores data in its
Data Blocks.
2) When vehicle comes to Gluing station, Error Proofing PLC sends VIN number together
with Gluing parameters to device PLC, then device PLC will execute Gluing operations
accordingly. When Gluing operation is done, device PLC sends its completion time of that
station to Error Proofing PLC.
3) When vehicle comes to assembly station, Error Proofing PLC sends VIN number and its
Gluing completion time to device PLC, then device PLC will validate the Gluing completion
time. If validation OK then do further operations.

B12 - Software Download
Now all vehicles have build-in computer, which has ECU(Electronic Control Unit).
ECU is the brain of a vehicle, which executes control logic in all modules including:
1) Fundamental functions, such as integration of brake, light, radar.
2) Management of transmission mode, such as switch of normal mode, sport mode, economy
mode.
3) Management of special mode, such as switch of two-wheels driving, four-wheels driving.
4) Vehicle history, such as driving miles, gas filling logs.
5) Integration of additional function, such as backward driving image.
6) Integration of entertainment, such as radio, mp3 player.
Even for the same type of vehicle, while having different configuration, it requires to
download different software accordingly.
In Final Assembly Shop, assembly line is flexible to meet customers’ unique
requirement.
Diagram 2.12-1 shows key process of Software Download.
Diagram 2.12-1 Software Download process

Firstly, we need to setup a software BOM system. In this BOM system, each software
will be regarded as a special virtual part, and will be defined with these attributes:
1) Virtual part number.
2) Version number.
3) Binary file.
Software BOM is quite similar in form as Engineering BOM and manufacturing BOM.
When MES generates a Work Order, it triggers MES to download whole software list
from Software BOM System.
Secondly, when vehicle passes PBS Out to come to Final Assembly Shop, conveyor
PLC will read RFID to identify vehicle, and sends VIN number to MES.
By querying VIN number, MES gets software BOM dataset, and sends it to Software
Download Server.
Software Download Server will check if it already has binary files in local, if not then
download from Software BOM System.
Then at last, when vehicle comes to Software Download station, worker scans barcode
of assembly sheet to get VIN number, the Software Download terminal will download binary
files from Software Download Server, and then down them to vehicle ECU.

B13 - Andon Calls
Andon system is used in vehicle plants widely, when issues are found in lineside,
workers can trigger calls with rope or button, and the call can be notified by
audio/light/screen.
Andon is the realization of 2 key management concepts:
1) Put quality first, line-stop is allowed to expose and resolve lineside issues.
2) Put line side assembly first, any other resource such as employees from
quality/maintenance/process/material handling should assist lineside workers and
machines, because assembly line’s efficiency defines plant’s efficiency.
This article will introduce some key elements of Andon system.
1. Call
Grouped by call type, Andon Calls can be categoried as Quality Call, Material Call,
Equipment Call, Conveyor Call.
Quality Call refers to situation of quality issues are found in lineside, which cannot be
resolved by worker himself, so worker pulls a rope or presses a button to trigger a call for
help. For this call, sender is worker, receiver is line leader and quality engineer.
Material Call refers to situation of material shortage, so worker presses material call
button. For this call, sender is worker, receiver is material handler. Normally each button will
be mapped to specific material, and it will be integrated to logistics execution system.
Equipment Call refers to situation of machine warning or machine error, which is trigger
by equipment controller automatically. For this call, sender is equipment PLC, receiver is
equipment engineer.
Conveyor Call refers to situation of conveyor line issues(such as stop, error, starve,
blocked), which is trigger by conveyor controller. For this call, sender is conveyor PLC,
receiver is line leader and equipment engineer.
2. Notifications
Andon system will provide multiple notification forms such as audio, light, screen.
Normally in working stations we will install stack light with 1 or 3 colors. For 1 color case,
it usually uses yellow light, and if Call is triggered, it will flash light to notify. For 3 color case,
normally it will use color of read/yellow/green, usually it’s used in key stations such as Error
Proofing stations, green light means normal, yellow light means warning, red light means
error. Stack light is integrated to conveyor PLC, which can act within 100ms.

In vehicle’s Final Assembly Shop, there’re lots of workers and machines, and engineers
will support multiple lines, so engineers might not see the stack light at lineside. So audio
notification system is also installed for broadcasting, which includes players + amplifiers +
speakers. The players are integrated into PLC, and can act within seconds, and can play
pre-record mp3 audio files.
Besides that, larger LCD/LED screens are also used to show words/tables/diagrams as
another form of notification. Large screen can be integrated into PC as external displayer, in
this PC, SCADA software such as WINCC/FTVIEW/CIMPLICITY will be installed, to show
information such as Call status, equipment state, planned quantity, actual quantity, buffer
data, shop layout.
3. Escalation
Calls have different level such as information, warning, error.
Information level includes case of shift change, when Call occurred, there’s no any
exception in lineside.
Warning level includes case of Material Call, Equipment Call, line starve, line blocked.
When Call occurred, the line is not normal but it’s still working.
Error level includes cases of machine fault, line fault, line stopped. When Call occurred,
it should be handled immediately.
The same Call such as Rope Call, can be referred to different level, there’s an
escalation mechanism behind it.
For example in Welding Shop, at moment of Pulling Rope, it will be defined as Warning
level, and if it’s not responsed within 10 seconds, then it will be escalated to Error level.
And in Assembly Shop, all stations have definition of 70% position, 90% position, 100%
position. At moment of Pulling Rope, if vehicle has arrived 70% position, then the Call will be
defined as Warning level; if 70% position is passed, then define Call as Error level; if 90%
position is passed and the Call is not resolved then line will be stopped.
When Call is escalated, the notification of audio/light/screen is also changed, for
example stack light flashes yellow as warning, flashes red as error.
4. Line stop management
In vehicle’s Final Assembly Shop, all stations are lined to conveyor line.
So if one station can not complete assembly job in time, then it require to stop whole
line, which means Andon system need to integrate to Conveyor PLC.
Normally Andon system will send these signals to conveyor PLC: line-stop signal, 0%
position signal, 70% position signal, 90% position signal.
Andon system has its own PLC, which can communicate with conveyor PLC via
industrial field coupler.

For conveyor PLC, after it received signal from Andon PLC, it will check with other
information such as line status, safety status, to decide whether to stop the line or not.
5. Shift management
Normally we will setup shift management in Andon system as well, even it has only 1
shift.
Because in plant, there’re lots of indexes related to shift, such as planned quantity,
actual quantity, stopped time, call time. These indexes are assigned to shift, and should be
reset on shift startup. Some indexes are collecting data from conveyor PLC, so Andon
system must send shift change signal to conveyor PLC, so that conveyor PLC can reset all
counters and timers accordingly.
Besides that, when shift is changed, Andon system can notify workers and mangers with
flashing lights and music.

Part C – System Architecture
C1 - Basic Architecture
MES is a big scale system, with features:
1) Act fast, normally it should response to client within 1~5 seconds, response to PLC within
1~2 seconds.
2) Has lots of function modules, including functions of planning, production, process, quality,
equipment, with lots of complicated business logic.
3) With high stability, normally requires availability of over 99.5%, otherwise it will have big
impact to lineside production.
4) Lots of interaction with external systems such as ERP, PLM, WMS, LES.
So to ensure its stability and availability, we need a really good system architecture for it.
Diagram 2.3-1 shows a typical architecture of MES system.
Diagram 3.1-1 Basic MES Architecture

Application Server is the core of MES, with functions of:
1) Definition of business model.
2) Definition of production routine.
3) Execution of business logic.
4) Handling input/output data.
5) Type/format conversion of data.
6) Execution of scheduled jobs.
7) OPC client to talk to OPC server.
8) MQ client to talk to MQ server.
9) DB client for Database read/write.
Normally application server will use cluster to provide higher availability.
Database is used to store data, normally MES uses Oracle or SQL Server.
Database includes Production Database and History Database.
Production Database is used for real time business handling, normally it only store data
within short period of time, it uses Technology such as DataGuard to improve availability.
History Database stores all historical data, normally is used for reporting.
So we can use Application Server to run real time data query from Production Database,
and use Report Server to run historical data analysis from History Database.
Network Server is used to handle input/output of clients, with functions of:
1) Graphic user interface.
2) Collect user input data.
3) Response to user operations of keyboard and mouse.
4) Execution of local scripts.
5) Load local DLL, for example, we can use .Net framework to run OPC client, so we can
have Distributed OPC communication.
Normally Network Server uses Network Load Balance to balance network traffic, so lots
of clients can run at same time.
In most cases MES uses network printers for printing work, so we need print server to
drive all network printers.
As for communication between MES and PLC, OPC is used for most cases.
OPC is a middle-ware platform, after installing correct drivers, OPC can map PLC’s data
stored in Memory or Data Blocks into Memory Tags of OPC Server, OPC Tags are similar as
other IT variables.
Now Kepware OPC Server is most popular, which supports almost all popular PLC, and
it also has some powerful plug-ins, such as IOT Gateway, which can pack OPC Tag into
standard Web Server.
PLC’s typical scan cycle is 50~100ms, and OPC’s scan cycle can be set to
250~1000ms.

MES has lot of data exchange with external systems such as ERP/PLM/WMS/LES,
normally MQ service is used to exchange data between systems. MQ can reduce coupling
between systems.
For example ERP is placed at corporate headquarter, PLM is places at R&D center,
MES is placed at plants, in that case, MQ server will be setup in corporate, and MQ clients
will be setup at corporate/R&D/plants, so that we can exchange data between systems.

C2 - Introduction of Kepware OPC
This article will introduce most popular OPC product: Kepware OPC Server and its plug-
ins.
1. What’s OPC
OPC is short of OLE for Process Control.
While OLE is short of Object Linking and Embedding.
An example of OLE is to insert an Excel table to Word.
Diagram 3.5-1: Function of OPC

From diagram 3.5-1, we can see that the key function of OPC is: to convert address of
PLC Data Block into Memory Tag, which can be read/write by MES via OPC client.
In best practice, if PLC needs to talk to upper systems, normally it will store data into
specific interface Data Block, which can be used by upper system easily:
Tag Data Type Address
HB_FLAG Bool DB1010.DBX0.0
DATA_READY Bool DB1010.DBX0.1
STATON_NUMBER Int DB1010.DBD2
SN String[40] DB1010.STRING4
But these address can not be accessed by MES directly.
After OPC mapping, these PLC Tags are similar to any other memory variables, and
OPC server can read/write them directly.
And we can install OPC client in MES server, so that we can read/write these Tags
easily.
Till now there’re 2 typical standard OPC protocols: OPC DA and OPC UA.
OPC DA is short of OPC Data Access, it’s based on Microsoft’s DCOM technology, it
has been used for decades, it’s very popular, but it can only be installed in Windows
platform. Due to limitation of DCOM, OPC DA has big security concerns, and it’s very
complicated to configure settings.
OPC UA is short of OPC Unified Architecture, it can be used in Windows platform, and
can also support Linux + Java environment, but it’s not used widely.
2. DataLogger
DataLogger is a plug-in of Kepware, it can log OPC Tag’s values into Database
automatically.
For the request of PLC data collection, this plug-in can match such request, it only
needs some simple settings, doesn’t require any coding.
After data is logged into Database, we can write logic in Database Procedures or
Application Layer, to handle the data accordingly.
For example, we need to run PMC in a Welding Shop, to collect equipment status data,
then we can use OPC DA + DataLogger to collect data, then we write a Trigger and a Stored
Procedure to handle the data.

3. ODBC Driver
DataLogger can only write Database, cannot read data from it, so data can only transfer
from PLC to MES.
But in some cases, PLC needs to read data from Database.
For example in Welding Shop, we need to download Orders and sync time to PLC, then
we can use ODBC Driver to accomplish it.
ODBC Driver configures Database as a special device, uses ODBC engine to connect to
Database and read/write data.
We can create 2 interface Table, one for storing Orders, one for time synchronization.
OPC server can read these 2 Tables, and then write data to PLC via OPC DA.
4. Advanced Tags
Advanced Tags is a group of plug-ins, here we introduce the most popular one – Link
Tag.
Link Tag can link 2 tags, so if 1st
tag changes its value, then 2nd
tag will change
automatically.
Here we introduce 2 use cases.
Use case 1: PLC communication. We do assembly in area A, and do checking in area B.
If we failed checking in area B, then Andon system needs to notify area A PLC. Considering
that the distance between 2 areas is quite long, and there’s not interaction between 2
processes. So we don’t need to add any additional hardware such as Coupler, instead we
can use OPC DA + Link Tag to communicate.
Use case 2: PLC updates data to MES. DataLogger can write Database with limitation: it
can only insert data. But ODBC Driver can update Table. So we can use OPC DA to monitor
PLC Tags, and with help of Link Tag and ODBC Driver, we can map them into data which is
stored in Database.
5. IoT Gateway
IoT Gateway is short of Internet of Things Gateway.
Kepware provides 4 types of IoT Gateway:
- MQTT client
- REST client
- REST server
- ThingWorx Gateway
The first 3 types are quite simple to configure and use.

MQTT is short of Message Queuing Telemetry Transport, is a specific message queuing
service used in long-distance and narrow-band network. For example in Machining Shop,
network signal is not quite stable, in that case we can use MQTT to collect PLC data without
upgrading network.
Rest is short of Representational State Transfer, is a widely used protocol which transfer
data in real time and stable.
REST client can monitor PLC tag, once it changes, then it will call MES REST server, to
push data to MES. For example as for vehicle travel record of AVI system, we can use REST
client to upload data in real time.
REST Server provides a listener, which expose PLC tags, and MES can call commands
via REST client. For example if MES needs to lock an Order, then it can write data to PLC
via REST client.
As for ThingWorx Gateway, it should be configured with Thingworx platform together.

C3 - Usage of IT PLC
IT PLC is widely used in vehicle manufacturing system, such as Ford NGAVS and Volvo
ANDON.
This article will introduce the function and architecture advantage of IT PLC.
Normally Andon system has its own PLC, because it’s very convenient to connect lots of
lineside hardware into single PLC.
In case of Painting Shop, lots of ropes, speakers, screens are installed distributed, if we
connect them to conveyor PLC, then there will be lots of conveyor PLCs need to connect and
integrate.
And with Andon PLC, together with remote I/O stations and Fiber network, we can
connect all hardware into same network, so it will be very convenient to install and integrate,
and it has lowest risk of impacting production.
Now let’s take an example of AVI system, without IT PLC VS with IT PLC.
Diagram 3.6-1 shows architecture without IT PLC:
Diagram 3.6-1: AVI without IT PLC
Diagram 3.6-2 shows architecture with IT PLC:

Diagram 3.6-2: AVI with IT PLC
By comparing these 2 architectures, we can see IT PLC’s functions:
First, from point view of conveyor vendor, by removing AVI Data Block and Function,
conveyor PLC’s business logic is quite pure, and has lowest impact to production. PN/PN
Coupler can map data from Data Block into I/Q Area, it’s very easy to integrate. Their project
only has business Data Blocks and Functions, it’s more stable, and has low coupling level.
Second, from point view of AVI vendor, because AVI Data Block and Function are
installed in same IT PLC, so they don’t need to consider the difference between conveyor
PLCs, that means it can suit all stations. And there’s no any conflict of Data
Blocks/Functions/Timers/Counters, so it’s much more simple to develop and debug.
Besides that, IT PLC can also provide some additional functions such as data buffer.
Considering lineside control network is much more stable than IT network, we can buffer
Orders after they are downloaded to IT PLC, and we can also buffer vehicle travel record into
IT PLC, so lineside control system has a soft coupling relationship with MES, so it has lowest
impact to production.

C4 - Soft Coupling
Working as execution system, MES needs to integrate with lineside devices and control
systems intensely, which is quite different than other IT systems.
For example, ERP releases orders with unit of day, manages warehouse with unit of
day.
But for MES, in situations of working with lineside devices, normally it’s required to work
with unit of second.
So MES requires very high availability.
And on the other hand, compared to PLC, MES is not so stable. So MES users will
suspect MES availability. So users require contingency plan of MES downtime.
The so-called soft coupling design is used to suit such cases.
Soft coupling is the opposite of hard coupling.
Hard coupling means both sides of an integration should always be active at same time,
1 side failure will cause the other side failure as well. Examples are Cummins NGMES, Ford
NGAVS, Volvo Andon.
As for soft coupling, while one side fails, won’t affect work of the other side.
Here’s some examples.
Case 1: cache data with barcode labels
Challenge: one vehicle final assembly shop, manufactures passenger car, SUV, MPV,
with 51 jobs per hour, how to ensure devices error proofing?
Solution: Print out error proofing barcode labels in assembly sheet.
When vehicle leaves PBS Out, MES prints out assembly sheet of it, with error proofing
barcode labels of all devices. Each label includes all necessary information such as model
type, process parameters for one device at one station. MES prints out these labels based
on process configuration, this step doesn’t need to interact with PLC.
When vehicle comes to error proofing station, operator scans error proofing barcode
label, then device PLC reads label and recognize character string from it, and then splits
string and decodes error proofing command. This step is done by PLC based on
configuration, doesn’t need to interact with MES.

Case 2: cache data with RFID Tag
Challenge: one engine assembly shop, manufactures many different types at same day,
and processes are modified quite often, so MES is required to suit the process changes, and
should have minimum impact to lineside production.
Solution: store process data in big storage RFID Tag.
Firstly, design a process management module in MES, so users can define and modify
process of each model type.
Secondly, when engine lifts on, MES queries process configuration of the engine based
on its model type, and get process parameters of each station, and transfers to PLC, and
then PLC writes data into 64KB RFID Tag.
Thirdly, when engine comes to assembly station, PLC reads station’s process
parameters via RFID Tag, and based on that, handles logic of assembly/torque/test
accordingly. When assembly is completed, PLC writes traceability data into RFID Tag.
At last, when engine lifts off, PLC sends all additional data back to MES.
We can see that, PLC only interacts with MES in real time at Lift On and Lift Off stations;
for most assembly stations, the operations are handled by PLC itself.
Besides that, because the processes are configured in MES, the configuration data are
stored in MES, so we can make changes easily with help of MES User Interface.
Diagram 3.7-1 shows related process:

Diagram 3.7-1: cache data with RFID Tag
Case 3: cache data in IT PLC
Challenge: one vehicle scheduling system, can download work orders into conveyor line
PLCs, and collects vehicle travel records from line PLCs. Now it’s required to have data
buffer of 2 hours, so if MES or IT network is not available in short time, it wouldn’t impact
lineside operations.
Solution: cache data in IT PLC.
As lineside key device, IT PLC can communicate and exchange data with conveyor line
PLCs in real time. In the same time, IT PLC can store data including the buffer data of work
orders for next 2 hours and offline vehicle travel records of last 2 hours.
Before work starts, planners will freeze orders in MES, which triggers system to
download orders (together with model type and other key vehicle data) to IT PLC, and then
IT PLC buffers the data inside specific Data Blocks.

When work starts, conveyor line PLCs request to download orders from IT PLC, then IT
PLC will search from local buffer and transfer to line PLCs; when IT PLC finds its buffer is
lower than safety number, then it will request MES to download new orders. When MES is
not functioning for short time, if IT PLC and line PLCs are still working normally, then IT PLC
can transfer its buffer orders, so the lineside operation can still continue without any impact.
At vehicle tracking stations, line PLCs collect vehicle information from RFID Tag, and
upload to IT PLC. IT PLC checks if MES is online, if so then upload data to MES, otherwise
buffer data in local Data Blocks. When MES is back to online, IT PLC will upload local
buffered vehicle travel record back to MES.

C5 - MES-PLC Handshaking Methods
In vehicle manufacturing, MES integrates with devices deeply, and in most cases integrates
via PLC.
This article introduces typical methods of MES-PLC handshaking and their features.
Method1: repeatedly collect data
For some devices, their key process parameters(such as temperature of heating oven) are
very important, need to collect repeatedly to generate real time diagram, and for summary
report and long-term analysis.
Normally these process parameters are analog data, and their values are changing
continuously.
We can read these data via OPC, and write into Database repeatedly.
The feature of these data: high read frequency, small range of data values, so there will be
lots of records with same values. Real-time Database is suitable to store such data.
Method 2: triggered by conditions
For lots of process parameters(e.g. torque values), their data are collected for traceability
analysis, we can define a trigger signal for MES to read.
For example while engine completes assembly in one station, PLC writes key parameter
values into Data Block, and set DATA_READY = true.
And MES will monitor DATA_READY every 1 second, when it’s set to true, then MES reads
all data from Data Block.
Refer to below time-sequence diagram:
Detail handshaking process:
1) Engine completes 1 step, PLC writes parameter 1.
Sender Receuver Data
PLC MES Parameter 1 1 4
PLC MES Parameter 2 2 4
PLC MES DATA_READY 3 4

2) Engine completes another step, PLC writes parameter 2.
3) Engine completes all assembly operations, PLC sets DATA_READY to true. Then MES reads
parameter 1, parameter 2.
4) Engine ready to leave current station, PLC resets all data.
Method 3: request-response mechanism, with 1
handshaking
For example when Engine Lift On, MES downloads Work Orders to PLC, the process can
refer to below diagram:
1) PLC writes request data(such as station) into PLC_MSG, then sets REQUEST_SENT = true.
2) MES monitors changes of REQUEST_SENT, then reads data from PLC_MSG, then generates
Order data and writes into MES_MSG, and sets RESPONSE_SENT = true.
3) PLC monitors change of RESPONSE_SENT, then reads data from MES_MSG, and writes data
into local Data Block, and then resets REQUEST_SENT and PLC_MSG.
4) MES resets all data.
We can see that, the data exchange only happened once(step 1 & 2), the step 3&4 are only
used to destroy data.
We can use this method to transfer different data in same station, for example download
Orders & upload travel records, the only difference will be data content in
PLC_MSG/MES_MSG.
Method 4: request-response mechanism, with 2
handshaking
The same example of Engine Lift On, the process can be referred to below diagram:
MES PLC MES_MSG 2 4
MES PLC RESPONSE_SENT 2 4
PLC MES PLC_MSG 1 3
PLC MES REQUEST_SENT 1 3

1) PLC writes data into PLC_MSG.
2) PLC sets REQUEST_SENT = true.
3) MES monitors REQUEST_SENT, and then reads data from PLC_MSG, then sets
REQUEST_RECEIVED = true.
4) MES writes Orders data into MES_MSG.
5) MES sets RESPONSE_SENT = true.
6) PLC monitors RESPONSE_SENT, then reads data from MES_MSG, and then copy data into
local Data Block, then sets RESPONSE_RECEIVED = true.
7) MES monitors RESPONSE_RECEIVED, then resets all data.
8) PLC resets all data.
We can see that, the whole process includes 2 handshaking, step 1-3 is the 1st
handshaking,
for sending request; step 4-8 is the 2nd
handshaking, for sending data.
This method is much more complicated than method 3, but it’s still used a lot. Because the
whole process will take several seconds, and PLC’s cycle time is only tens of ms, so the
additional signals can be used as state marker, which helps to reduces anxiety of waiting,
and the signals can also be used to debug.
Method 5: based on manufacturing process
At some stations, there will be multiple key process, such as in Engine Lift On station, engine
will be Lift On, then assembly, then upload travel record.
So in a typical manufacturing process, PLC needs to exchange data with MES twice, 1st
time
for Order download, 2nd
time for travel record upload, as referred as below diagram:
MES PLC REQUEST_RECEIVED 3 7
MES PLC MES_MSG 4 7
MES PLC RESPONSE_SENT 5 7
PLC MES PLC_MSG 1 8
PLC MES REQUEST_SENT 2 8
PLC MES RESPONSE_RECEIVED 6 8

Detail process:
1) Engine arrives, PLC sets ENGINE_ARRIVAL = true.
2) PLC checks device and material, then sets STATION_READY = true.
3) MES sets STATION_READY_RECEIVED = true.
4) MES writes Orders into MES_DATA.
5) MES sets MES_DATA_SENT = true.
6) PLC copies MES_DATA into local Data Block, then sets MES_DATA_RECEIVED.
8) PLC starts assembly operations, then writes Engine number into ENGINE_SN.
9) While assembly is completed, PLC sets PLC_COMPLETE = true.
10) MES sets PLC_COMPLETE_RECEIVED = true.
11) MES executes logic of travel record, and then sets MES_COMPLETE.
12) PLC sets MES_COMPLETE_RECEIVED.
14) Engine readies to leave, PLC sets ENGINE_LEAVE = true.
15) PLC resets all data.
We can see that, this method is very complicated, but it has these additional advantages:
1) All key states are captured, and can be monitored via HMI.
2) PLC states are referred to actual production status, can be used to track down while errors
happen.
3) When application errors happen, we can see which step of communication is executed to.
MES PLC STATION_READY_RECEIVED 3 7
MES PLC MES_DATA 4 7
MES PLC MES_DATA_SENT 5 7
MES PLC PLC_COMPLETE_RECEIVED 10 13
MES PLC MES_COMPLETE 11 13
PLC MES ENGINE_ARRIVAL 1 15
PLC MES STATION_READY 2 15
PLC MES MES_DATA_RECEIVED 6 15
PLC MES ENGINE_SN 8 15
PLC MES PLC_COMPLETE 9 15
PLC MES MES_COMPLETE_RECEIVED 12 15
PLC MES ENGINE_LEAVE 14 15
Order Download Assy Travel record Upload

C6 - Journey of a bolt
In this article, I will take an example of a bolt, to explain how WMS(Warehouse Management
System) and MES(Manufacturing Execution System) are used and integrated.
Bolt is a class of key components, has big impact to engine quality.
Below table lists out key process control points:
Area Station/Position Operation System
Warehouse WM100 Store components in box WMS
Kitting WM200 Pack bolt with spring and other
materials
WMS
Assembly OP10 On assembly completed, call for
material pull delivery
automatically
MES → WMS
OP20 Manual assembly, manually call
for material pull delivery if
necessary
MES → WMS
OP30 Pre-tighten bolt by manually MES
OP40 Final tighten bolt by robot MES
Below chart shows high level process:
Now let’s analyze it from perspective of material delivery, assembly and material pull.
1. Material delivery
Delivery of bolt has 3 big steps:

1) Receives in bolt from vendor’s cargo, unpack and inspect, and then transfer to specific storage
area in warehouse, with position WM100.
2) Transfers bolt from warehouse to kitting station WM200, here operator packs bolt with spring
and other components together.
3) Uses AGV to transfer packed bolt to assembly station OP20.
To match with such requirement, we need to set below BOM info in WMS:
Material Description Stock
No
Position
BT0010 Bolt xxx 10 WM100
BT0010 Bolt xxx 20 WM200
BT0010 Bolt xxx 30 OP20
2. Assembly
Assembly of this bolt includes 3 stations:
1) In OP20, operator put bolt into right position. In this example, we have quantity 4 of this bolt.
2) In OP30, operator uses torque gun to pre-tight the bolts. If the station has been configured with
8 torque guns, and here we only need to user gun 1-4.
3) In OP40, robot will final tight all bolt, with sequence of 1-4-3-2.
Then the assembly BOM should be:
Station Material Quantity
OP20 Bolt xxx 4
OP30 Bolt xxx 0
OP40 Bolt xxx 0
When engine arrives at station OP20, stack light of bolt will turn on, until operator picked 4
times, then stack light will turn off.
The torque gun error proofing is configured in MES:
Statio
n
Gun#
1
clicks
Gun#
2
clicks
Gun#
3
clicks
Gun#
4
clicks
Gun#
5
clicks
Gun#
6
clicks
Gun#
7
clicks
Gun#
8
clicks
Sequenc
e
OP30 1 1 1 1 0 0 0 0 00000000
OP40 1 1 1 1 0 0 0 0 14320000
In OP30, after gun 1/2/3/4 has completed tightening, error proofing of the gun is completed;
when all 4 guns has completed tighten, then the error proofing of this station is completed,
then PLC allows engine to leave.
In OP40, robot will tighten bolts with sequence of 1-4-3-2.
3. Material Pull
In this example we have 2 layers of material pull: 1) assembly to pull from kitting; 2) kitting to
pull from warehouse.
When assembly of OP10 is completed, MES will generate a travel record, and sync it to
WMS, WMS will alert operator of WM200 to do kitting before engine comes to OP20.

When assembly of OP20 is completed, and if operator finds he doesn’t have enough material
for next engine, then he can call for material with push button, the call message will be
transferred to kitting area via WMS.
The logic of kitting area pull: each time AGV delivers material to assembly area, WMS will
decrease material number of bolt in WM200, when the number is less than safe storage
number, then WMS will send the pull message to mobile device of warehouse delivery
operators, so they can deliver it from warehouse accordingly.

Part D – Project Management
D1 - Communication management
In vehicle manufacturing, MES is a very complicated system, covering functions of
planning/production/process/equipment/quality, relates to lots of process, and needs to
cooperate with lots of departments.
Besides that, for a large vehicle company, it’s also required to handle the relationship
between corporate departments and plant departments.
Below chart shows a typical MES organization architecture of a vehicle plant.
Diagram 4.1-1 MES organization architecture
We can see that, from MES point of view, as an execution system, MES’ direct
customers are production executors(operators and machines), the other departments of plant
should support production, and all departments of corporate should support local
departments accordingly.

Besides that, while building a new plant, it’s designed by corporate departments on early
stages, and then designed by plant departments later, and there will be gaps between
corporate and plant regarding some process or requirement.
So during MES implementation, we will face these 2 challenges.
1. Challenge 1: how to understand business?
In recent years as concept of Industry 4.0 has been introduced to public, MES market is
expanded, and more and more talents joined into MES area. But the fact is, there’re still not
many people understand the process and requirement of vehicle manufacturing.
So it’s inevitable that lots of gaps between business and IT on requirements will happen.
To reach high understanding, we need to innovate in organization architecture.
Now let me introduce a best practice: Cummins MES.
Cummins MES is a corporate system, developed by one team globally, implemented by
one team globally, operated by one team globally.
The develop team is based in headquarter, team members include IT talents(architect,
technical experts, vendor experts) and business talents(business experts, control experts),
running as a virtual team.
The business experts have 10+ years of experience in engine building, they’re very
familiar with building process and quality standards. They will talk with process engineers
and quality engineers to understand all details of any new requirement, and try to align
between different plants. So the requirements submitted by business experts are really the
thoughts of plants.
The control experts know how to control lineside devices and how they are interact with
MES. They will talk with control engineers and vendor engineers, to define standard control
protocols.
IT team members are working in same office with business experts and control experts,
so IT can work closely with business and avoid misunderstanding during communication.
2. Challenge 2: how to align business?
Now lots of vehicle makers are large companies, with plants located worldwide. So even
on implementing universal MES, there will be gaps for different plants.
From corporate’s perspective, MES should be designed to be standard solution, and to
use one team to develop, deploy and support.
So how to balance corporate standards and plant customization?
Here I introduce a method for reference.

We can setup 2 expert committees, MES business experts committee, MES control
experts committee. The team members should be experts from corporate and plants. Each
expert has vote right, while corporate experts have more vote weight.
So while one requirement cannot reach alignment, we can arrange a vote inside experts
committee, and get an agreement with highest vote score. The develop team should develop
based on it as standard template. If a plant still need customization, then develop team can
realize it during implementation with lower priority.

D2 - Planning
Due to unique process of vehicle building, the planning of MES implementation is very
different than general software system.
1. Milestones
Building a vehicle plant has these milestones:
- TT, short of Tool Tryout, or Tooling Trial, is referring phase of equipment setup and
configuration, MES is cut-over during this phase.
- PP, short of Pilot Production, the Logistics Execution System is cut-over during this phase.
- SOP, Start of Production, ERP system is cut-over during this phase.
For ERP system, normally we’ll setup test system at first, then prepare master data, then
configure and test, finally load data to production system, and cut-over during SOP.
But for MES, it needs to integrate with lots of equipment, and we must use time window
of TT to test.
Normally on TT phase, there’re few vehicles available for test, only a couple of vehicles
for each shop, and will stop in case of any issue. But since PP, the daily planning quantity
will increase, so it’s not suitable for handling any test related to interface with equipment.
There’ll be a couple of months between TT and SOP, which brings a challenge of project
management: MES and ERP are normally managed by same IT program, but since they
have different cut-over time, so it will be quite difficult to align planning and resource.
2. Develop pattern
MES is cut-over at TT, which brings concern of develop pattern.
In recent years, affected by internet development, agile develop pattern is quite popular,
but in vehicle building MES area, traditional waterfall + modular pattern is more suitable.
Consider that equipment integration should be ready and tested in TT phase, and ERP
interface should be tested in SOP phase, so we need to develop and test equipment
integration module in advance.
Another feature of MES is: Normally we setup production system, then develop and test
in that system directly. There’re 2 reasons: firstly, the test of OPC&PLC must be referred to
physical servers, the successful test on test system doesn’t mean success on production
system. Secondly, in production system, there’re availability mechanism such as data guard
of Database, load balance of Web Server, and cluster of Application Server, and such
features cannot be tested in test system.

3. Equipment Debugging
For MES, the debugging/test of equipment integration are planned at TT phase, when
the plant is still under construction, for some area the power and network might not be
available yet, which requires temporary power and network, so lots of stations might need a
couple of turns of debugging.
Each function module should go through these debugging process:
- Power and network test, to check infrastructure such as O/S, client, network.
- Communication test, also known as heart beat test. Equipment PLC sends out a heart beat
signal, then MES receives it and responses back. This step is to check the basic
handshaking between equipment and MES, it could also check communication parts such
as Couplers.
- Virtual business test. Before physical vehicle is available, PLC/HMI sends out virtual
business data, then MES responses according to business logic and handshaking protocol
accordingly. The reason is that there’re only few vehicles available at TT phase, and
there’re lots of stations require debugging, so we need to do as many tests as possible
while IE engineers are available.
- Physical vehicle test. It happens after virtual business test, to check the physical devices
such as sensors, encoders, and also do final test of whole process.
In debugging phase, different debugging process might happen in same time. For
example in Welding Shop, there’re 10+ IE engineers, but only 1 MES engineer, so the MES
engineer might debug heart beat at one station in the morning, and test virtual business at
another station in the afternoon.
As per detailed time planning, we should reserve 1 week for the 1st
station covering all
test process, because the 1st
station covers lots of common issues such as setup of OPC
and Gateway. Then for 2nd
and 3rd
stations 3 days should be reserved for each one. After
that reserve 1 day for each later station. 2 weeks later reserve half day for each later station.

MES in Vehicle Manufacturing

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