Resetting Cpu Memory; Possible Causes For The Cpu Memory Reset Request - Siemens SIMATIC S7-300 Hardware And Installation Manual

9.6.3 Resetting CPU memory

When do you reset CPU memory?
You must reset CPU memory,
• Before you download a (completely) new user program to the CPU
• If the CPU requests memory reset with its STOP LED flashing at 0.5 Hz
intervals Possible reasons for this request are listed in the table below .
Table 9-3
Causes of a CPU request to reset
memory
The Memory Card or MMC has been
replaced.
RAM error in CPU
Main memory too small, that is not all
user program blocks on a Memory
Card or MMC could be loaded.
Attempts to load faulty blocks; e.g. if
the wrong instruction was
programmed.
How to reset memory
There are two ways to reset CPU memory:
Memory reset with the mode selector
switch
... is described in this Chapter.
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02

Possible causes for the CPU memory reset request

Remarks
Does not apply to CPU 312 IFM /
314 IFM (314-5AE0x)
–
CPU with inserted 5 V FEPROM Memory Card
(not CPU 31x)
With these causes the CPU requests one
memory reset. After that, the CPU ignores the
contents of the memory card, enters the error
reasons in the diagnostics buffer and goes to
STOP. You can erase or reprogram 5 V FEPROM
Memory Card in the CPU.
CPU with MMC inserted: A further memory reset
is requested.
Additional information on MMC behavior after a
memory reset can be found in the CPU Data
Reference Manual, Memory concept chapter.
Memory reset with PG
... only possible if the CPU is in STOP mode
(seeSTEP 7 Online Help).
Commissioning
9-15