Introduction - If you have any usage issues, please Google them yourself
OMRON CPM2A PLC with the 8051 single-chip communications applications (RS-232C)
Packet : 121114116omron_cpm2a_communication_protocol_and_application_using_at89c52_microcontroller.zip filelist
OMRON_CPM2A_Communication_Protocol_and_Application_using_AT89C52_Microcontroller.pdf