I have spent several hours trying to establish communication via RS232 with an AB SLC500 /w an L532 CPU that has its DH485 port tied up w/ a Panelview that can't be taken down w/o dumping the plant. It's the only overall view HMI in the plant and has been programmed failsafe if it loses communication w/ the PLC so RS232 is the only option. I have tried everything that I can think of to talk to this rack but no joy. The RSLinx DF1 RS232 drivers fail on error checking or come back with "unable to establish communication" and "check cables and connections" messages. I can simply unplug from the CPU and tie onto my own test unit L531 CPU)and be online everytime. Does any one know if firmware rev can cause this issue? Has anyone else encountered this problem or one similar? If anyone here has advice that may help me resolve this difficulty please post or email me.
Thanks, Rick
Thanks, Rick