Omron C28H Comms problems

Some help please if you can.

I recently discovered an old omron C28H-C6DR-DE plc hidden in a panel in the factory. I have been trying upload the program from this without any success so far. The PLC is connected to a Omron NT20S HMI via the RS232-C port on the PLC. I have tried communicating with the PLC through the RS232-C port using a Omron XW2Z-200S-CV cable and syswin 3.4 but I can't get to talk with the PLC. Is there a set up issue with the RS232-C port because it is using this to talk to the HMI. If so it is possible to change the settings using a programming console to then allow me to upload the program for backup purposes??

Do I need to aquire a Host link unit for this PLC and if so is the 2G2A6-LK201-EV1 the correct unit?? I am loathe to buy a unit for 1 plc but if needs must then so be it.

Do I have any other options??

All advice and help appreciated.

Cable

I think the cable may be the issue.
Unlike almost any other Omron PLC with a 9 pin port, the H series processors used pin 7 for signal ground, not 9.
Attached is the cable diagram for the C**H processors.
Moving the SG wire from pin 9 to pin 7 on the PLC side of the cable should solve the problem.
You can check the communications parameters of the port through the System menu of the NT20S.

Thanks for that.

Will swop the SG wire over and give it a try. Believe it or not the cable I was trying to use was recommended by Omron.

I understand.
This is an old product, and to my knowledge there are no other Omron serial ports that used pin 7 for SG on a 9 pin port.
It would be easy for someone to assume that it was the same pinout as all other Omron 9 pin ports.

Tried the modified cable this afternoon and it worked spot on.

Many thanks for the help.