1756-RM2/A Redundancy Module Disqualified (at times)

Hello,

My 1756-RM2/A Redundancy Module keeps entering the Disqualified module for half an hour or so, and then switches to Synchronized for like 10 hours straight.

During failure, the Event Logs say:
1. Partner not on same link
2. Firmware failure (minor fault)

Checked the firmware of the module. it's same as the Primery Controller.

Any suggestions?

Thank you.

"Partner not on same link" suggests that there's something wrong with the fiber cable in between the RM2s.

RM module faults usually require sending the log files to RA Tech Support. They're not common or easy to diagnose.

Partner not on the same link means that Ethernet (or ControlNet) modules in primary and secondary chassis don't see each other via network.

For Ethernet, I would start checking the network connection.

Hey, thanks... I was thinking that "link" might mean the network, not the Redundancy link.

I've run into this on some early redundant HMI and ControlLogix reudundancy systems where there were networks that would disconnect from one another under certain conditions, and that disqualified the Secondary.

I think this is done because the Ethernet and ControlNet modules need to be able to swap addresses quickly, and if they aren't on the same network they can't be sure that they can do so.

Had the same problem two times. The first time it was a controlnet tap adapter on the Remote I/O. Another time it was caused with a slight vibration to one of the processors. We barely moved the processor and it disqualified itself. It could also be a network problem. If that en2t drops of the network it will become disqualified.