if you do not need the clock, then you can
also store the values in an EEPROM
(integrated in PLC). This does not require
any additional HW.
To write to the EEPROM will create a DB.
So your data must be in V-Memory.
1. Use SMB31 & SMW32. Max. 4 Bytes can
be written, you can use it several times.
2. Use www.s7-200.net and load the
library free of charge.
3. If only a view data has to be stored,
then you can write it to MB0..MB13 and
select retentivity in the system block for
this merker range. MB0 .. MB13 if
retentiv, will be stred in the PLC internal
EEPROM automatically.
4. If you do not change the values during
operation, means you set the values only
one time, then you can also use MW and
select PLC; Create DB from RAM. This wsill
generate a DB with the complete V-
memory.
5. Use the battery to extend to 200 days.
Please be carefull with writting to
EEPROM. max. write cycles 100.000. So
dont write to EEPROM in each cycle.!!!!!
I hope this s.

Trich automation.siemens.com