This is tutorial to give you basic concept for modbus protocol (ModbusTCP, ModbusRTU), and how to troubleshooting with modscan/modsim tool

1. Advantech Communication Training:
Modbus protocol
IAG Inter-corn AE
Alex Hsieh (謝明宏)

2. Outline
• Modbus protocol introduction
• Modbus transmission modes
• Advantech Modbus solution
• Troubleshooting tools

3. Modbus protocol introduction
• Why we need a communication protocol?

4. Modbus protocol introduction
• What is a common communication protocol? English!!!

5. Modbus protocol introduction
• Devices need a common language! Modbus protocol !!!

6. Modbus protocol introduction
• Modbus is a serial communications protocol originally
published by Modicon (now Schneider Electric) in 1979 for
use with its programmable logic controllers (PLCs).

7. Modbus protocol introduction
• The main reasons for the use of Modbus in the industrial
environment are:
1. developed with industrial applications in mind
2. openly published and royalty-free
3. easy to deploy and maintain
4. moves raw bits or words without placing many restrictions on
vendors
• Modbus protocol is the common language that is used by
different vender controllers.

8. Modbus Transmission Modes
• Learning map
Protocol Data formatInterface
Serial
Ethernet
1.Modbus/TCP
2.Modbus/RTU
3.Modbus/ASCII

9. Modbus Transmission Modes - Protocol
• Protocol
• Communication : Query–Response Cycle
• Client/Server vs. Master/Slave
Modbus TCP Modbus RTU Modbus ASCII
Interface TCP/IP Serial Serial
Commend type Hexadecimal (base 16) Hexadecimal (base 16) ASCII (base 256)
Master Slavepolling
Response
One polling, One response
Client ServerRequest
Response
One request, One response

10. Modbus Transmission Modes – Data format
• PDU = Function code + Data
• ADU = Address + PDU + Error check
No check sum

11. Modbus Transmission Modes – Data format
• Address : Station address
e.g. Slave ID or IP
• Function code : indicates the function code
e.g., read coils/holding registers
• Data : Data + length will be filled depending on the message
type
• Error check : check if get the correct information
e.g. CRC/LRC

12. Modbus Transmission Modes – Data format
• Main Modbus function code
• Function code : R/W Modbus address table
Function Code Action Table Name For address
01 (01 hex) Read Discrete Output Coils 0x
05 (05 hex) Write single Discrete Output Coil 0x
15 (0F hex) Write multiple Discrete Output Coils 0x
02 (02 hex) Read Discrete Input Contacts 1x
04 (04 hex) Read Analog Input Registers 3x
03 (03 hex) Read Analog Output Holding Registers 4x
06 (06 hex) Write single Analog Output Holding Register 4x
16 (10 hex) Write multiple Analog Output Holding Registers 4x
address Point type Coil/Register Numbers Data Addresses Type Table Name
DO 0x 01:coil status 1-9999 0000 to 270E Read-Write Discrete Output Coils
DI 1x 02:input status 10001-19999 0000 to 270E Read-Only Discrete Input Contacts
AI 3x 04:input register 30001-39999 0000 to 270E Read-Only Analog Input Registers
AO 4x 03:holding register 40001-49999 0000 to 270E Read-Write Analog Output Holding Registers

13. Advantech Modbus solution
• ADAM-4000 (Modbus/RTU)

14. Advantech Modbus solution
• ADAM-6000 (Modbus/TCP)

15. Advantech Modbus solution – Facility Management
• PAC : APAX-55XX (Modbus/TCP and Modbus/RTU)

16. Advantech Modbus solution – Real Application
• The real-time monitoring system creates an ideal growing environment for greenhouses
• Market: Greenhouse Monitoring
• Location: Taiwan
• http://ppt.cc/zGX0V
Modbus/TCP

17. Advantech Modbus solution – Real Application
• Solar Energy Water Heating System Monitoring
• Market: Power & Energy
• Location: Portugal
• Customer: PRIREV
• Technology Partner: Ffonseca
• http://ppt.cc/XrDQj
Modbus/RTU

18. Troubleshooting tools
• Modbus utility
• Modbus protocol ref
1. Wiki: https://en.wikipedia.org/wiki/Modbus
2. Simply modbus: http://www.simplymodbus.ca/index.html
Utility Master /Client Slave /Server
Basic ModScan32 ModSim32
Advanced ModPoll ModSlave
Master Slavepolling
Response
One polling, One response
Client ServerRequest
Response
One request, One response

19. Troubleshooting tools – Modsim32/ ModScan32
• ModSim32 – simulated Modbus/TCP server in local PC.
• ModScan32 – simulated Modbus/TCP client to R/W data.
• IP: 127.0.0.1 (default setting)
Name Address index Start address length Address
Write_DO 0x 0 16
0x00001-
0x00016
Read_DI 1x 0 16
1x00001-
1x00016
Read_AI 3x 0 8
3x00001-
3x00008
Write_AO 4x 0 8
4x00001-
4x00008

20. Troubleshooting tools – Modsim32
• ModSim32/ ModScan32 – Demo

21. Modbus protocol – Modsim32
• ModSim32 : open file  simulate folding  4 simulated file

22. Modbus protocol – Modsim32
• ModSim32 : connect to Modbus/TCP server

23. Modbus protocol – Modsim32
• ModSim32 – simulated modbus/TCP server in local PC.
• IP: 127.0.0.1 (default setting)
DO AI
DI AO

24. Modbus protocol – ModScan
• ModScan32 : open file  simulate folding  4 simulated file

25. Modbus protocol – ModScan
• ModScan32 : connect