I’m currently working with a WAGO PFC200 (750-8212) PLC in CODESYS and running into issues with serial communication. Ethernet communication is working perfectly, but RS232 and RS485 are not responding at all.
Setup:
PLC: WAGO PFC200 (750-8212)
Software: CODESYS (04.06.01)28 FW
Hardware: 05
Libraries: WagoAppModbus,SysCom / WAGO Serial libraries added successfully
Ethernet (TCP/IP): Working fine (PLC reachable and communication OK)
Issue:
RS232 is not working
RS485 is also not working
No data transmission or reception observed
Key Observation:
Using the WAGO Ethernet Settings tool:
TCP/IP communication works without any issue
But COM port communication (COM1 / COM7 via WAGO cable) does not work
This makes me think the serial interface may not be enabled or configured correctly at the system level. Additional Info:
WBM (Web-Based Management) settings are already configured under Administration
Serial interface settings have been checked and set as required
What I’ve Tried:
Added and configured serial libraries in CODESYS
Set baud rate, parity, stop bits properly
Performed loopback test (TX ↔ RX) → no response
Verified wiring and connections
Tried both RS232 and RS485 interfaces
Confirmed PLC works fine over Ethernet
Questions:
Why does COM communication via WAGO Ethernet Settings tool fail while TCP/IP works?
Are any additional drivers or runtime packages required for serial communication?
Goal:
To get RS232/RS485 communication working from a CODESYS application on the PFC200.
Any suggestions, configuration steps, or working examples would be greatly appreciated.
Picture is too grainy for me to see what device you have populated in the Codesys UI. When I add a PFC200 device a serial interface with COM1 populates automatically.
I am attempting to set up Modbus RTU communication where the PC (using CODESYS Control Win SysTray) is configured as the master, and the WAGO PFC200 (750-8212) PLC is configured as the slave.
Initial post was referring to the PFC200 so I’m going to go there: If you are trying to get the PFC200 setup for modbus communication you will need to add it as a separate device in the Devices tree. From there you can configure and connect to it which will send down your configuration, associated libraries, and programming. For testing I would setup a job with only the PFC200 and then test it with your laptop using a 3rd party app like Modscan64.
In regards to the serial connection using the Ethernet setup tool - I believe that is referring to the com port on your laptop connecting to the PFC200 service interface using a configuration cable (750-923).
Yes, my initial setup is with the PFC200. I understand that the Modbus configuration needs to be done by adding the PFC200 as a separate device in the CODESYS device tree and downloading the configuration.
I have already configured the device and I am trying to test Modbus RTU communication with:
PC (CODESYS Control Win SysTray) as Master
PFC200 as Slave
However, the issue I am facing is not only at the Modbus level, but at the serial communication level itself.
RS232 and RS485 ports are not showing any TX/RX activity
Even a loopback test is not working
So it seems the serial port is not active or not accessible
Regarding your point about the Ethernet Settings tool:
Yes, I am using the configuration cable (750-923) from my laptop COM port.
But even with that, COM communication is not working, while TCP/IP works fine.
So currently, it looks like:
Serial interface on PFC200 is not enabled or blocked at system level
Because even basic communication is not working before Modbus testing
If you have any suggestions on enabling or verifying the serial port (RS232/RS485) at system level, that would be very helpful.
Only other things I can think of are the following …
PFC serial port pin designations: I’ve only setup RS485 - I know the pin designations were as expected and could not use an off the shelf serial converter. I had to make up a cable with pin 3 (+) and pin 8 (-).
I’ve only setup a Modbus Master. Comm settings are part of the VAR setup and the port designation is called out when the Master is instantiated in the program.
