Modicon TSX Micro - Modbus Communications


Thread Starter


Hello All,

I am working on a project and really need some assistance. I have a Modicon PLC, TSX 3721101. I need to be able to connect to this PLC and do two things: read data registers (for an old home grown SCADA application) and alter the PLC program using PL7. I can perform both of these functions using a PC with RS232 port connecting to the term port of the PLC with cable TSXPCX1031. I know that to program the PLC the cable forces the TERM port to communicate using the UNI-TELWAY protocol. This requires a specific switch setting on the cable. To collect the data I am using MODBUS RTU. This requires a different cable switch setting.

Here is my problem: the PLC and switch in the cable are not easily accessible. I have easy access to the DB9 connector but not the rest of the cable. Is there a way to communicate with the PLC so that I can still obtain my data using Modbus and be able to program without having to change the switch? One other point, I do have the ability to change the PC serial port to RS-482 or RS 485. If I need to replace the cable I can do so.

Thank you for your help.