Siemens S7-400 - Cold, Warm, and Hot Restarts with the Mode Selector Switch

Starting Up
6-10
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
6.6 Cold, Warm, and Hot Restarts with the Mode Selector
Switch
Sequence of Events During a Cold Restart (CPU 417 and 417 H)
1. Turn the switch to the STOP setting.
Result: The STOP LED lights up.
2. Turn the switch to the RUN/RUNP setting.
Sequence of Events During a Warm Restart (CPU 417 and 417 H)
1. Turn the switch to the STOP setting.
Result: The STOP LED lights up.
2. Turn the switch to the MRES setting and keep it at this setting.
Result: The STOP LED is dark for one second, bright for one second, dark for
one second and then remains lit.
3. Turn the switch to the RUN/RUNP setting.