Modicon Modbus communication


Thread Starter

C. Lai

Could someone tell me if I can connect 2 Modicon Quantum CPU modules through their Modbus comm. port through 2 modems.

Thanks so much.

Jonathan Blanchard

Yes, The Quantum can communicate through its Comm port 1 to a modem. If you are programming in 984
Ladder Logic you will need to use the XMIT function block. If you are programmimg in IEC then you will have to use the XXMIT function block. Remember that only one PLC can act as a Master on a Modbus network at a time.
Thanks for your answer. I don't have XMIT function block (it has to be purchased separately as you are prbably aware of it). I am using ProWORX software to write the logic, guess I'll have to use BridgeMux in between the 2 modems in order for the 2 CPUs to talk, right? Of course I'll have to use MSTR function block then.

Any other solution? Thanks again.