Hello Geospark,The cable you were attempting to make is an RS485 electrical wiring cable. The TXD, RXD & COM signals are all you need for DF1 or DH485 protocol. As I said, make the other cores safe.
If you have null modem & PM02 cable combination working ok, I would stick to that.
I would still be curious to know if the RS485 cable worked. We only make up our own cables as the PV is some distance away from the controller.
Did you upgrade the firmware on the PV before loading the MER?
It's always good to know how to do these things.
Please do let us know your final setup.
Thank you very much.
The system comm. now, I follow your and Ken's suggestion, make it works now, I checked PV+ fireware vision, then when I create runtime file, I choose the version is match the PV+vision. then make a cable according to your suggestion-one end of Rs232 connected to 1761-CBL-PM02's 9 pin end, and another end of RS232 changed to 4-2,7-3, 2-5 , then this end connect to PV+, so it works.
I am here to thank you and Ken as well as everybody!!!!