Remark 1: Setting the Parameters Auto Run and MOD \ Using the Display/Keypad

Loading and running the user program also depends on the setting for the parameter MOD using the display/keypad (in AC500 CPUs PM57x, PM58x and PM59x). The display/keypad setting always has the higher priority.

The following applies:

MOD 00:	User program will be loaded and run according to the setting for the CPU parameter “Auto run” (default setting).
MOD 01:	User program will not be loaded/will not run.
MOD 02:	User program will be loaded and run independent of the setting for the CPU parameter “Auto run”.

Keeping the RUN push button pressed when booting the PLC automatically activates MOD 01, i.e. the user program is not loaded/does not run. Thus, it is possible to boot the PLC in Stop status. This may be required if, for example, both serial interfaces are set to MODBUS and therefore no access with the Control Builder software is possible via the serial interface.

Note

On CPUs PM55x and PM56x, a RUN/STOP switch is designed for the MOD function.

If the RUN/STOP switch is set to STOP mode before the CPU module is powered on, the program in the CPU will not run after the CPU is powered on. The program can only be executed when the switch is set to RUN mode and the program is downloaded on the CPU again.

If the serial interface COM1 or COM2 is set to communication mode in a running program (e.g. MODBUS communication), it can be changed back to other mode (e.g. online access to Control Builder software) only by setting the switch to STOP mode.