Solution of my CPU 224 pb
I received this message from SIEMENS support (after sending a plc program to SIEMENS support) :
Dear Mr. Harik,
Retentive area MB0 to MB13 is OK
But SMB31 and SMB32 I found in the “Saving_routine” SBR8. this part of the program damage the CPU! You set the V31.7 too often. I guess every scan. Every time if you set this bit, the PLC writes to the EEPROM. The maximum write cycles are restricted! Please ensure that the PLC only writes if it is necessary! E.g. only if anyone had changed parameter on the OP3.
I suggest, change your program and also change your CPUs against new ones.
More information’s you found in the System manual Page 39 (PDF 53)
http://support.automation.siemens.com/WW/view/en/1109582
If you use the Program in more CPUs, set the CPU as soon as possible in STOP mode! Please change the program.
have a look to
http://support.automation.siemens.com/WW/view/en/17471561
extract from the manual:
Tip
Since the number of save operations to the permanent memory (EEPROM) is limited (100,000
minimum, and 1,000,000 typical), you should ensure that only necessary values are saved.
Otherwise, the EEPROM can wear out and the CPU can fail. Typically, you should perform save
operations at the occurrence of specific events that occur rather infrequently.
For example, if the scan time of the S7-200 is 50 ms and a value was saved once per scan, the
EEPROM would last a minimum of 5,000 seconds, which is less than an hour and a half. On the
other hand, if a value were saved once an hour, the EEPROM would last a minimum of 11
years.