We have an industrial floor that is opened and closed by a variable speed drive motor. This is controlled by a PLC device. Recently we had to do maintenance on the VSD. The serviceman incorrectly diagnosed that the VSD wasn't working because the battery had died. We had the VSD serviced and its all working again. The problem was with the VSD. However we determined it wasn't the battery since it was drawing power from the PLC.
I'm interested to know if it is common for this type of configuration? Should the serviceman (he was employeed due to claimed extensive knowledge of such systems) have known about this?
sorry I can't provide the hardware details of the VSD/PLC don't have these handy. I will try and get the specific config details this weekend.