M Decoding Acc. To List - Siemens SINUMERIK 840D sl Function Manual

P3: Basic PLC program for SINUMERIK 840D sl
13.10 Structure and functions of the basic program
The symbolic names, commands and absolute addresses can be viewed by means of a STEP
7 editor command when the UDT block is opened.
Note
Unused bits and bytes are listed, for example, with the designation "f56_3".
● "56": Byte address of the relevant data block
● "3": Bit number in this byte
13.10.9

M decoding acc. to list

Function description
Up to 256 M functions with extended address can be decoded from the basic program using
the "M decoding according to list" function. The function is activated using FB1 parameter
"ListMDecGrp" (number of M groups for decoding). The assignment of the M function with
extended address and a signal in the signal list is defined in the decoding list. The signals are
also grouped for this purpose.
Decoding list (DB75)
The source file for the decoding list (MDECLIST.AWL) is supplied with the basic program. Data
block DB75 is created when the STL source is compiled. Before the function is activated, the
decoding list (DB75) must be transferred to the PLC followed by a restart.
An M function is decoded if it is in the decoding list. When decoding the M function, the
corresponding signal is set in the signal list as a function of the specific group. When setting
a signal in the signal list, the interface signal "Read in inhibit" is set by the basic program in
the associated channel of the NC. The interface signal is reset again for the channel as soon
as the user resets all of the signals output from this channel in the signal list; i.e. after they
have been acknowledged.
Signal list (DB76)
When activating the function in data block DB76, the basic program creates the signal list.
From then, for each M signal decoded according to the list, a signal is set in the signal list
(DB76) in the corresponding group. At the same time, the "Readin inhibit" interface signal is
set in the channel in which the M function has been output. The interface signal is reset again
for the channel as soon as the user resets all of the signals output from this channel in the
signal list; i.e. after they have been acknowledged.
Highspeed auxiliary functions
When an M function contained in the decoding list is output as "fast help function", no read-in
inhibit is set for the corresponding channel of the NC.
The figure below shows the structure of the M decoding according to list:
860
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions