Presenter - Boris Cherkasskiy The industry-wide demand to collect and present machine statistical and performance data is continually growing. While it’s possible to IoT-enable a machine with the use of an Intelligent Gateway or by utilizing an MES system, it might be cost-prohibitive for a small machine. This session will present a solution that allows you to push data from an S7-1200 PLC directly to the cloud via standard MQTT protocol. Attendees will gain a quick path to Industry 4.0 using standard IoT protocol to connect a custom machine (or a cell/line) to an existing and fast-growing IoT infrastructure.

1. Pushing Data from S7-1200 to
Cloud
Automation Summit
Boca Raton, FL, June 26-28, 2017

2. DMC Overview
Established in 1996, DMC serves customers worldwide from offices in
Chicago, Boston, Denver, Houston, New York, and St. Louis
employees & growing
120+

3. Siemens Expertise
31 Siemens Certified Engineers

4. DMC Customers

5. Automotive Chemical & Food Processing
Consumer Goods Defense Contracting Energy & Utilities Food & Beverage
Packaging Pharmaceutical Printing & Textiles Semiconductor
Special Machinery Telecommunications Test & Measurement
Industries Served

6. Presenter Info
• M.S. in Systems Engineering – Chelyabinsk State University (Russia)
• With DMC since 2004
• Siemens Certified Professional
• Embedded system experience
Boris Cherkasskiy
Principal Engineer (Denver)

7. Agenda
• Project overview. Have this
problem been solved before?
• Communication options
between PLC and IoT
• Communication protocol
implementation on PLC side
• Overview of visualization
platforms

8. • Goal: Report machine status to easy-accessible dashboard
• Not an issue if you have SCADA/MES
• Challenging for machine-level control system
• Cost effective approach
Project Overview

9. • Chart recorder (my personal favorite)
• SCADA/MES system
• OTS data collection options
• Custom data collection solutions
Classic Approach

10. • Utilize well-developed visualization platforms
already available for IoT application
• Minimize intermediate hardware/software
• Use familiar technology (PLC)
• Inexpensive/free to operate
Proposed Solution
Cloud-based visualization

11. • Simple to set up, no “programing” required*
• Nearly real-time updates
• Web interface
• Mobile application
Benefits of the Solution

12. • Another cool term?
• Any device object connected to the Internet?
• Can one thing talk to another thing? Sure thing!
• It seems to be mostly used for dashboard-style applications
• Multiple web-enabled visualization options
Short Overview of IoT

13. • Target machine-level application
• Easy to use, familiar to automation engineers
• Supports variety of industrial protocols
o ProfiNet
o Modbus
o ProfiBus
• Unclear how to make it communicate
to the existing IoT infrastructure
Siemens S7-1200 Overview
PLC
protocols
IoT
protocols?

14. • On hardware level it could be anything, from custom audio
(including Morse code!) to Ethernet, WiFi, etc.
• Data protocols, could be anything too:
IoT Protocols Overview
Protocol Notes
Custom protocols Application-specific, non-standard
REST (Representational State Transfer)
HTTP (Hypertext Transfer Protocol)
Websocket (Part of HTML5)
SOAP (Simple Object Access Protocol)
Heavy to implement, requires extensive computing
power/resources to create and parse human-readbe
data (strings)
MQTT and MQTT-SN Much simpler/lightweight protocol

15. • Works on to of the TCP/IP protocol (PLC-friendly)
• Event-driven protocol
• Publisher/subscriber architecture
• Flexible message delivery/acknowledge mechanism (QoS)
MQTT Protocol Overview
Publisher
Broker
Subscriber
Subscriber
Subscriber
Topic
Topic
Stat/Temp or
Bottle_temp

16. MQTT Protocol. QoS
Publisher
Broker
Subscriber
Subscriber
Subscriber
Topic
Topicat least once
* QoS 2 is not supported by some platforms discussed later
Stat/Temp or
Bottle_temp

17. • Very simple protocol (the whole spec is ~50 pages)
• Binary protocol
o Low bandwidth
o Small memory footprint
• Widely accepted in IoT world
• Supported by IBM/Facebook/Amazon/Microsoft/etc.
• Lets implement MQTT on the PLC!
Is MQTT Suitable for PLC/IoT Communication?

18. Simplicity of the protocol has some downsides:
MQTT Downsides
Issues Mitigation
Data type is not defined as part of the protocol Vendor defines data formats. Just follow their rules
No encryption implemented as part of the protocol Could run over SSL (requires Secure Sockets Layer) 
But, SSL is not implemented on the PLC side 
Login information transmitted as clear text Key/token is transmitted instead of the actual password
There is no server identity verification Implemented as one way communication only.
Predefined response size, harder to craft malicious
packets
All of the above Run your own local MQTT broker. Bridge local MQTT
broker to the Internet via secured channel (MQTT over
SSL, VPN, etc.)

19. • Could address security concerns
• Easy to run your own broker (broker is pretty simple application)
• Local MQTT Broker could bridge messages to another Broker
• Example: http://www.eclipse.org/mosquitto/download
Run Your Own MQTT Broker

20. Protocol Implementation on the PLC Side
fcMQTT_string
or
fcMQTT_dint
dbMQTT_Queue
fbMQTT
PLC
NETWORK
MQTT Broker
(local or cloud)
Overall Architecture
Example is available here: https://github.com/boriz/MQTT-SN-Arduino/blob/master/S7-1200/MQTT_Demo_V14.zap14

21. Protocol Implementation on the PLC Side
PLC example

22. Demo Unit

23. Cloud-based broker is usually included with visualization platform.
• Multiple Android-based dashboards. Probably the simplest option.
• Adafruit – Targets DIY/makers community. Very simple to use.
Still in “alpha” limited mode.
• IBM Watson – Very capable, flexible platform. Not trivial for outsiders.
• Microsoft – Probably pretty advanced. But…
Data Visualization

24. There is one issue with it: Unencrypted MQTT is not allowed by default
• Flexible IoT protocol gateway
• Standard (unencrypted) MQTT implementation is actually
one of the examples
• Programming required – Partially defeats the ideal of “simple” solution
• Probably worth future investigation/discussion
Data Visualization – Microsoft Azure IoT Hub
Where to find it: azure.com

25. • Very simple platform
• May be a bit limited for advanced stuff
• Only few things to configure:
o Key is auto-generated
o Feeds = topics
o Dashboard through GUI
o Still in “alpha” mode
Data Visualization - Adafruit
Where to find it: io.adafruit.com

26. Data Visualization - Adafruit
Configuring/Viewing Feeds (topics)

27. Data visualization - Adafruit
Configuring/Viewing Dashboard

28. • Advanced platform. May be a bit confusing to configure.
• Example mapping IBM Watson fields to the MQTT topic.
o MQTT topic: iot-2/evt/status/fmt/json
o MQTT message example: {"d":{"OEE":66}}
• Seems to be still work-in-progress with a few bugs here and there
(selecting property in the card)
Data Visualization – IBM Watson
Where to find it: internetofthings.ibmcloud.com

29. Data Visualization – IBM Watson
Configuring/Viewing Dashboard

30. Data Visualization – Android (MQTT Dash)
Very easy to configure, but limited
Where to find it: search “MQTT Dash” in Google Play

31. Questions?

32. Appendix
PLC Implementation Details

33. Description of FCs
• Only 2 blocks/data types implemented so far
o DINT – Integer
o String – Universal/everything else
• Value may need special formatting (IBM)
Protocol Implementation on the PLC Side
fcMQTT_string
sInTopic
iInQoS
sInValueFormat
sInValue
fcMQTT_dint
sInTopic
iInQoS
sInValueFormat
diInValue

34. Format String explanation
• sInValueFormat is empty string – pass Value parameter as is
• sInValueFormat is not empty – find and replace <<value>> in the
format string with actual value and pass it to the queue
Example:
sInValueFormat: {"d":{"Message":”<<value>>”}}
sInValue: “Hello world”
String sent to the MQTT Broker: {"d":{"Message":”Hello world”}}
Protocol Implementation on the PLC Side

35. Overview of fbMQTT input parameters
• iInQueueSize – how many elements in the
dbMQTT_Queue datablock
• sInClientID – some services (IBM) requires
specific Client ID
• sInUserName – user name (usually, “use-
token-auth” for IBM)
• sInPassword – password/key/token
• bInCleanSession – not very important for
publishing. Set to 1 in most cases
• bInResetError – Reset bit/push button/etc.
Protocol Implementation on the PLC Side
fbMQTT
iInQueueSize
sInClientID
sInUserName
sInPassword
bInCleanSession
bInResetError

36. End Presentation
Track: Maintenance & Operations
Connect Event ID Session #10.5