Siemens S5-135U/155U System Manual page 147

Mode Switch
The mode switch has two settings:
RUN
In the RUN setting, the CPU 948 processes the user program when the green
RUN LED is lit.
STOP The CPU 948 goes to the stop state when you switch from RUN to STOP.
The red STOP LED then lights up.
Momentary-
You can initiate the Overall Reset, Reset and Restart functions with the
Contact Mode
momentary-contact mode switch:
Switch
OVERALL RESET Momentary-contact switch down
With an overall reset, all RAM areas are erased and initialized (both on the
CPU and on a RAM submodule).
RESET Momentary-contact switch up
During a reset, all flags, timers, counters and the process image will be
erased. OB 20 will be invoked. Processing of the user program will start from
the beginning again.
Restart Momentary-contact switch at midpoint
With a restart, processing of the user program will continue from the point of
interruption. The statuses of flags, timers, counters, and the process image
are retained during stoppage of the CPU.
System Manual
C79000-G8576-C199-06
CPUs, Memory Cards, Memory Submodules, Interface Submodules
5-7