Siemens S7-200 224 cpu

How long does the 224 hold its memory. I guess I could look on Siemens web site, but I don't have 3 days to spare. I guessing it's slightly longer that 2 days. I have many of these in the field and only one customer that is having a problem. He has been turning power off to the machine for extended periods of time.

Bill

A supercapacitor retains the memory for a few days(4-5 if I remember correctly)
An additinal battery will retain the mememory for about 6 months.
If set to retentive, MB0 - MB13 are saved to EEPROM when the system powers down.
Another options is to save values, entered setpoints for example, to EEPROM by software, see SMB31 and SMW32

Thanks. I did find the battery backup on siemens web site. I need to find out how many customer issues we have before I change the code.


Thanks again

My experience with the super-cap is weeks, even months.

pp

I vaguely remember reading somewhere that the supercap can retain retentive data for 100 days, If you are more concerned about losing retentive data then add an eprom module and use the program to write any retentive data to the eeprom that way if (assuming the user can change parameters like times/counter values etc) a value gets changed the new value is written to the eeprom and when a loss of retentive data occurs the new changed value will still be recalled along with the program/data block(s) etc.

I found a spec on siemens web site. "190 hours"