Hi, this is jay... i am tring to learn handshaking between Omron CP1H Plc and Click Plc. Honestly I dont know any thing about this, posting this topic is my first step. both of my PLC has RS232c communication capability. I want to undestand RTU and ASCII modbus communication. I have builtin communication in click plc and CP1W-ClF01 unit for CP1H.CP1W-ClF01 is snap on optional communication board for CP1H. I have tried to find litrature about handshaking btwn PLC but did not get good source......so i need help for everything. thanks . jaymeen patel