momemtum crash

Hello,

My one customer has an Schneider momemtum plc, model# is 171CCS78000. Somehow yesterday some water got sprayed in their control cabinet and this plc quit. They dried it out and powered it up and everything in the control panel worked except for the vfds that were networked from this plc.

The Mod+ light was flashing but the run light was not on. We cycled the power but that made no difference. I understand that the only way to get these back in run mode is to connect from a PC so we we removed the plc and took it into the office where it was easier to work with a laptop. We powered it up there and , lo and behold, the run light came on. So we took it back out in the plant and powered it up and connected each of the comm cables individually. (there is not i/o on this, just comm). Everything powered up fine and the run light came on again. We reset the faults on the vfd and then the system worked great.

Can someone possibly offer an explanation of what we did that could get this to jump back into RUN mode? Took us all by suprise.

Is it possible you may have a some water droplets on the network cables causing a short between pins. Then by removing the connectors and placing them back the water didnt short between pins anymore?