Siemens SINUMERIK 840D sl Function Manual page 1048

Detailed description
2.7 Structure and functions of the basic program
Structure of FB 1 in the OB100
(enter the number of M groups to be decoded in order to activate the function):
Call FB 1, DB 7(
...
ListMDecGrp := 3,// M decoding of three groups
....
);
The appending of the entry in OB 100 and transfer of DB 75 (decoding list) to the AG must
be followed by a restart. During the restart, the basic program sets up DB76 (signal list).
If the NC program is started at this point and the expanded M function (e.g., M3=17) is
processed by the NCK, this M function will be decoded and bit 2.5 set in DB 76 (see
decoding list DB 75). At the same time, the basic program sets the read-in disable and the
processing of the NC program is halted (in the corresponding NC-channel DB the entry
"expanded address M function" and "M function no." is made).
The readin disable in the channel is reset once the user has reset and, therefore,
acknowledged, all the bits output by this channel in the signal list (DB 76).
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Basic logic functions: PLC Basic program powerline (P3 pl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0