[?]: PLC-PLC connection via radio modem using RS232/RS485

ggmahyar · Post by **ggmahyar** » Wed Feb 13, 2008 10:37 am

In a project there are 7 PLCs communicating together with radio modems (output RS232) and the designer has considered CP341 (RS232) modules for the PLCs.

Q1: Does it work since we can not use any addressing? Can we use Modbus protocol with that module?

Q2: What shall we do to solve it? Change from RS232 to RS485 version?

rataman · Post by **rataman** » Sun Feb 17, 2008 12:16 am

i used rs-485 with modbus library with s7-200, you can use rs232 also with radio links, it creates some kind of virtual cable, but use modbus. You should buy modbus donghles from siemens for that cpu and every thing will be fine.