Siemens Simatic S7-1500 CPU 1512C-1 PN User Manual page 179

Data record structure
The example in the figure below shows the structure of data record 64 for channel 0. The
structure is identical for channels 1 to 31. The values in byte 0 and byte 1 are fixed and must
not be changed.
You enable a parameter by setting the corresponding bit to "1".
Figure B-5
CPU 1512C-1 PN (6ES7512-1CK01-0AB0)
Manual, 12/2017, A5E40898741-AA
B.6 Structure of a data record for output channels of the digital on-board I/O
Structure of data record 64: Bytes 0 to 3
Parameter data records
179