Siemens SIMATIC Manual page 529

Structure of data record 1
The figure below shows the structure of data record 1 for the parameters of digital output
modules.
You enable a parameter by setting a logic "1" at the corresponding bit of byte 0.
Figure A-3
Note
The "hold last valid value" and "set substitute value" parameters should only be enabled at
byte 0 as an alternative.
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
Data record 1 for parameters of digital output modules
Parameter sets of signal modules
A.4 Parameters of digital output modules
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