All the channels on this rack are seen as in error by the processor, but the other racks are not affected. The values of the inputs in error are no longer updated in the application memory and are reset to zero in a discrete input module, unless they have been forced, when they are maintained at the forcing value.

If the failure period is less than 10 ms for alternating current power supplies or less than 1 ms direct current power supplies, the failure is not detected by the program, which will run as normal.