The TM172PDG42RI 42 I/O PLC is not polled using the Modbus RTU protocol (RS485-1 and RS485-2 ports)

[viy-777]

Hello! The task is to poll the PLC using the Modbus RTU protocol (by RS485-2).
All the necessary settings have been made:
1. In the Configuration for RS485-2, the mode was set to "Modbus Slave-BACnet MS/TP"
2. In "Commissioning", I set the type to "Modbus", the device address, and the parameters (8n1)
3. Full compilation, full load, reloaded the PLC, disconnected the USB
The survey should be carried out according to the operator panel by project. I connected for testing with a USB-RS converter. I started the "Scanner RTU" and found the device.
I started the OPC server, but there is no register survey (error: cannot open the COM port).
Please advise on a solution to this problem. Is this what I'm doing?
P.S.: I used both version 1.4.0 and 1.6.0. I updated the firmware to 596.14 (the PLC had 596.12).

[M_Cervati]

Hi,

it seems all ok, but I didn't see the COM port selected in the modcan32. Is it COM6?

If you try to use RS-485-1 with the same settings the result is the same?

Thank you

Marco Cervati

[viy-777 · Accepted solution]

It worked. The converter driver was installed incorrectly on the PC.