Setting the "IOM Hold Bit" A500.12 (CS1/CJ1/CJ2) will hold the state of Inputs and Outputs during changing of PLC mode, for example from RUN to PROGRAM for a transfer of parameters and then returning to RUN. In addition, this behaviour can be maintained in case of power failure via the PLC Settings menu by ticking the Startup Hold: "IOM Hold Bit" option.

In contrast, the "Output OFF Bit" A500.15 forces OFF all Outputs on Output Modules when the CPU is in RUN, MONITOR, or PROGRAM mode. Note that CPU LED INH reminds you that the forcing is in operation.