We are developing an application on a WAGO CC100 (751-9402) using CODESYS V3.5. The controller has two RS-485 interfaces, both currently used by the CODESYS application for Modbus RTU communication. We would like to occasionally access one of these same RS-485 interfaces from a Linux application ru…

Hello, I am Matthew Kim, living in South Korea. I read your post with interest and am leaving a reply. Are you attempting to use the two RS-485 ports on the CC100? Is the plan to use one port as a constant RTU, while using the other as an RTU but pausing it temporarily to execute external RTU com…

Hi, Thank you for your message. We use both RS485 interfaces on the CC100 to communicate with external devices using Modbus RTU. Therefore, Modbus RTU is required. We access the CC100 remotely through a VPN. For testing purposes during the pre-commissioning phase, we would like to run a communica…

[image] Using RS485 port on CC100 with NodeRED Node-RED Thanks, Damian. I just tried this on a 751-9301 (FW28) with your image and it worked! I think you already check about this topic. If that is not the case, please check the relevant topic. Please pr…

My suggestion is to instead of setting up a Modbus RTU master device in codesys, setup a Modbus TCP Server where you enable Serial gateway on a specific com port and baud rate. Then you can have “unlimited” number of clients accessing the RTU-lines via Modbus TCP. Codesys will then communicate with …

I have not tested this, but another possibility is to use the Modbus function blocks in Codesys rather than the configurator. It may be the case that setting the xConnect input to FALSE will cause the FB to release the RS-485 port. It was unclear if you are using the CC100 as client or server, but …

Hi, no I did not see this article. Thank you. Sorry for the late reply, I have been very busy these days. :smiling_face:

Thank you, but it does not work for us. We do not want to add another device. It means higher cost.

Hi, we do not use the Codesys configurator. Our system is based on FBs. The Codesys configurator is an easier solution, but it is not flexible and is slower than using FBs directly. We need full control of the Modbus. We use two RS485 ports in parallel to minimize scan time. It works very well …

You dont need to add another device. The CC100 can act as the gateway as illustrated in my images.

Accessing the CC100 RS-485 interfaces from Linux while CODESYS is using them

CODESYS

MatthewKim September 17, 2026, 1:20am 4

I think you already check about this topic.

If that is not the case, please check the relevant topic.

Please provide further feedback.

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Accessing the CC100 RS-485 interfaces from Linux while CODESYS is using them

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