Stop_Unit Handling

If the driver receives a STOP_UNIT command from the I/O Server for a particular device, then the driver places the unit offline and adjusts the polling rate based on the inactive scan adjust. When the INIT_UNIT command is received again, the driver will start polling again and place the unit back online.

If the unit is currently offline, the STOP_UNIT command will not be sent down to the driver so the driver will not know to stop polling the PLC.