Siemens SIMATIC S7-400H - Cold Restart; Operating Sequence for Memory Reset; Protection Levels of a S7-400 CPU

Installation of a CPU 41x-H
4-13
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Table 4-3 Protection levels of a S7-400 CPU
Protection
Level
Function Switch Position
1 • All programming device functions are permitted
(default setting).
RUN-P/STOP
2 • It is permissible to load objects from the CPU into
programming device. In other words, only read
programming device functions are permitted.
• Functions for process control, process monitoring
and process communication are permitted.
• All information functions are permitted.
RUN
3 • Functions for process control, process monitoring
and process communication are permitted.
• All information functions are permitted.
–
If different protection levels are set with the mode selector and with STEP 7, the
higher protection level applies (3 before 2, 2 before 1).
Operating Sequence for Memory Reset
Case A: You want to download a complete, new user program to the CPU.
1. Turn the switch to the STOP setting.
Result: The STOP LED lights up.
2. Turn the switch to MRES, and keep it in this position.
Result: The STOP LED is dark for a second, light for a second, dark for a
second and then remains on.
3. Turn the switch back to STOP, and then within the next 3 seconds turn it back
to MRES and then back to STOP.
Result: The STOP LED flashes for at least 3 seconds at 2 Hz (memory reset is
executed) and then lights up continuously
Case B: When the STOP LED flashes slowly at 0.5 Hz, the CPU is requesting
a memory reset (system memory reset request, after a memory card has
been removed or inserted, for example).
Turn the switch to MRES and back to the STOP position.
Result: The STOP LED flashes for at least 3 seconds at 2 Hz (a memory reset
is executed) and then lights up continuously.
You can find the complete description of what happens during a memory reset in
the: S7-400, M7-400 Programmable Controllers Installation Manual, Chapter 6.
Cold Restart
Following a cold restart, the user program starts from the beginning again. All the
data, including the retentive data, are deleted.