Siemens SINUMERIK 840Di Function Manual page 1240

Detailed Description
2.7 Structure and functions of the basic program
Description
Abbreviated symbolic names of the interface signals are defined in the two STL files
NST_UDTB.AWL and TM_UDTB.AWL.
In order to create the reference to the names of the interface signals, the name is included in
the comment after each signal. The names are based on the English language. The
comments are in English.
The symbolic names, commands and absolute addresses can be viewed by means of a
STEP7 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
2.7.9 M decoding acc. to list
Description of functions
When the M decoding according to list function is activated via the GP parameter of
FB1 "ListMDecGrp" (number of M groups for decoding), up to 256 M functions with extended
address can be decoded by the basic program.
The assignment between the M function with extended address and the bit to be set in the
signal list is defined in the decoding list. The signals are grouped for this purpose.
The signal list contains 16 groups with 16 bits each as decoded signals.
There is only one decoding list and one signal list, i.e., this is a cross-channel function.
The M functions are decoded. Once they are entered in the decoding list, then the
associated bit in the signal list is set.
When the bit is set in the signal list, the read-in disable in the associated NCK channel is set
simultaneously by the basic program.
The read-in disable in the channel is reset once the user has reset all the bits output by this
channel and thus acknowledged them.
The output of an M function decoded in the list as a high-speed auxiliary function does not
result in a read-in disable.
2-46
PLC Basic Program Solution Line (P3 sl)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0