Description of Functions
9-41
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
Retentive storage of parameter data
Please note the following when using the function “Write parameters with retentive
storage” (byte 4, job type 4):
Retentive writing must only occur on demand (not cyclically)!
Retentive data are stored on FEPROM (maintenance-free, no battery required).
This memory has a physical limit for the possible number of delete/reprogram
cycles: minimum 10
5
, typically 10
6
. The possible number of delete/reprogram
cycles can be multiplied, from the user’s viewpoint, by providing a larger retentive
memory capacity (much larger than the parameter data memory) and organizing
the memory accordingly.
Number of delete/
reprogram cycles
=
64 000 10
6
(typical)
Block size (in bytes), in which param-
eter data are modified
Block sizes:
DB machine data 284 bytes
DB increments 468 bytes
DB tool offset data 308 bytes
DB traversing programs 108 + (20 x no. of traversing blocks) bytes
Example:
Assuming a service life of 10 years and 24-hour operation, a typical limit = 10
6
.
Parameteriza-
tion data
DB size Number of possible delete/
reprogram cycles
Number of possible delete/
reprogram cycles per min-
ute
MD 284 by-
tes
237.04 10
6
46
Traversing pro-
grams (20
blocks)
508 by-
tes
125.49 10
6
24
Note
SDB 1 000 (system data block, created for module replacement), contains pa-
rameter data which were valid at the time of start-up. If data/parameters are modi-
fied during operation and stored retentively on the FM, these data are not con-
tained in SDB 1 000. These modifications are lost when the module is replaced,
and should be traceable in the user program.
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