Thanks IO_Rack, I make the DB9-DB9 cable as your diagram, when It connect to CS1W-CIF31 pigtail, it is able to read another OMROM's PLC but not CPM2A
. I see the TD LED on the CS1W-CIF31 flash, and CX-One is trying different baud rate, finally said can not find CPU. There is a NT21-ST121B-E HMI connect to the CPM2A use the the same RS232 port. I try to connect the HMI and CPM2A to read the program, both fail.
My CPM-2A have a little switch besides the port and it is set to "ON"
Any clue?