ModbusTCP OPC/UA Driver - ADAM-4572 ModbusRTU Gateway Connection Issues

[jpai]

Hello,

I am attempting to read holding registers from an Advantech ADAM-4572 using the OPC/UA ModbusTCP driver to no avail. I am trying to establish a test setup before attempting field work, and I am not sure if my ADAM configuration, Ignition ModbusTCP driver configuration, or both are wrong.

Virtual Testing

• For a sanity check, I plugged in two USB RS-232 adapters and made sure the ModbusRTU slave was working using virtual Modbus master/slave programs. I set the first 12 holding registers and was able to read them successfully.
  (The excellent Modbus Tool repo is here: GitHub - ClassicDIY/ModbusTool: A modbus master and slave test tool with import and export functionality, supports TCP, UDP and RTU. )
  
  

ADAM-4572 Settings

• Settings:
  
  
  
  
  

Ignition OPC/UA ModbusTCP Driver Settings

• Settings (all advanced settings are default):
  
  
  
  
  
  
  
  

Ignition OPC Tags

• Tags:
  
  

Wireshark diagnostics

• ADAM is configured configured with static IP (.240). Wireshark indicates that communication is occurring between the Ignition server (.31) and ADAM (.240). Interestingly, Ignition sends ModbusTCP requests, and the ADAM returns TCP (not ModbusTCP) responses.
  

  

• I used ModbusMaster to create a virtual ModbusTCP master to try to connect to the ADAM and got similar Wireshark results as above.

Does anyone have any ideas? Please let me know if you need more information or screenshots. Thank you.

[Kevin.Herron]

Start by modifying all of your tags' OPC Item Paths so the include a prefix of 1.. This sets the unit/slave id to 1, instead of the default of 0, which is virtually never correct when you're talking to a Modbus TCP to RTU Gateway.

e.g. [MyDevice]1.HR1

edit: 1, or whatever the actual slave address is supposed to be. Depends on how the serial device is configured.

[jpai]

I am on it! I will let you know what happens.

[jpai]

I set all of the tags with the format you mentioned ([ADAM]1.HR1). Example:

Also, I double checked that my virtual ModbusSlave is set for ID: 1.

My tags are reading are still 'Bad' after the change. Since the virtual ModbusTCP master program is having similar issues, I think this is pointing to a configuration issue with my ADAM module, unless you see something else off with my Ignition settings.

[Kevin.Herron]

Ignition settings look fine, if other masters also can't read it's probably a problem with the ADAM like you suggest.

I'll leave you with 2 other pieces of advice for the Ignition side:

• don't be tempted to use the Address Map page, just define the tags like you're already doing
• disable all but 1 tag you know exists until you have established comms and a successful read

[jpai]

Thanks for the advice and immediate response! I will disable all but one tag and diagnose the ADAM settings from here and report back if I find anything.