How To Use The Mode Selector To Reset The Memory; Internal Cpu Events At Memory Resetting - Siemens SIMATIC IM 151/CPU Manual

STOP
LED
On
Off
3 s
RUN-P RUN-P
STOP STOP
MRES MRES
1. 2.
Figure 4-1

How to Use the Mode Selector to Reset the Memory

Is the STOP LED Not Flashing at Memory Resetting?
Does the STOP LED not flash during memory reset or do other indicators come
on? You must repeat steps 2 and 3. If the IM 151/CPU still doesn't execute a
memory reset, you have to read out the diagnostic buffer of the CPU component
with the programming device (see the STEP 7 user manual ).
What Happens in the CPU Component of the IM 151/CPU?
Table 4-3

Internal CPU Events at Memory Resetting

Event
Sequence of 1. The CPU deletes the entire user program in working memory and
operations in the
CPU component of
the IM 151/CPU
2. The CPU deletes the backup memory (retentive data).
3. The CPU tests its own hardware.
4. If you have inserted a memory module (micro memory card =
Memory contents The user program from the memory module is transferred to the
after reset working memory again.
What's left? The contents of the diagnostic buffer and the runtime meter.
ET 200S Interface Module IM 151/CPU
A5E00058783-01
Max. 3 s
RUN-P RUN-P
STOP STOP
MRES MRES
3.
Response of the CPU in the IM 151/CPU
the load memory.
MMC), the CPU copies the relevant contents of the module to
the working memory.
Commissioning and Diagnostics
Min. 3 s
RUN-P
STOP
MRES
t
4-5