Siemens SINUMERIK 828D Function Manual page 887

P3: Basic PLC Program for SINUMERIK 840D sl
13.8 Structure and functions of the basic program
Figure 13-14 M decoding acc. to list
Activation of the function
The number of groups to be evaluated / decoded is indicated in the basic program parameter "ListMDecGrp"
when FB 1 is called in OB 100 (see also " FB 1: RUN_UP Basic program, start­up section [Page 925] "). M
decoding is activated if this value is between 1 and 16. Before the function is activated, the decoding list DB75
must be transferred to the PLC followed by a restart.
Structure of decoding list
The source file for the decoding list (MDECLIST.AWL) is supplied with the basic program. DB 75 is created when
the STL source is compiled.
There must be an entry in decoding list DB 75 for every group of M functions to be decoded.
A maximum of 16 groups can be created.
16 bits are available in each group in the list of decoded signals.
The assignment between the M function with extended address and the bit to be set in the signal list is specified
via the first and last M functions in the decoding list.
Basic Functions
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0