On the MKV simplex a logic point which is also a <C> contact output is written to by a normally closed bigblock output. The bigblock is also in <C>. Modbus reports this contact output point changing state fleetingly, however the contact output does not physically change state. The logic can be forced and behaves normally. The toggle does not happen all the time, and seems to occur at random times, unrelated to machine operation or activity on the station. The logic can set and reset every second or so when it does toggle. The Modbus has been checked thoroughly and operates correctly on all other points. There are no LCC or communications errors.
Any thoughts or pointers to help resolve this would be appreciated.
Any thoughts or pointers to help resolve this would be appreciated.