Hey everyone, I’m reaching out to see if anyone has encountered and resolved a similar issue with Modbus RTU communication in Citect SCADA. I’ve been working on setting up communication with a device over the internet using Modbus RTU over TCP/IP. The device ID is 1, and port 80 is open for the Modbus protocol. I’m trying to read a float value starting at address 0.
To test the setup, I used Modbus Poll software, and it worked perfectly! I received the expected value without any issues. However, when I switched to Citect SCADA 2016, the driver went offline, and the kernel log indicated that it couldn’t communicate with the device. I tried adjusting various parameters in the Citect INI file, such as Initvar, InitVarType, ConnectTimeout, and PollTime, but nothing seemed to resolve the issue.
I also used Wireshark to diagnose the problem. Interestingly, the Modbus Poll software sent the correct message to the target device, but Citect did not. Additionally, I noticed that the first poll attempt with Modbus Poll resulted in a timeout error, but the second request worked correctly. This behavior led me to adjust some parameters in the Citect configuration, but unfortunately, it didn’t make a difference.
I’m wondering if anyone has experienced similar issues and if there are specific configurations or troubleshooting steps that could help resolve this problem. Any insights or suggestions would be greatly appreciated! Thanks in advance for your help.