Siemens Sinumerik 840D sl Programming Manual page 117

Note
All the above commands must be programmed in separate blocks.
The number of markers depends on the CPU used.
Channel numbers
Up to 10 channels can be specified as channel numbers (integer value) for the channels
requiring coordination.
Channel names
Channel names must be converted into numbers using variables (see "Variables and
arithmetic parameters"). Alternatively, the channel names defined using $MC_CHAN_NAME
(identifier or keyword) can also be programmed rather than channel numbers. The defined
names must comply with the NC naming conventions (i.e., the first two characters must be
either letters or an underscore).
Protect the number assignments so that they are not changed unintentionally.
The names must not already exist in the NC with a different meaning, e.g. as key words,
commands, axis names etc.
SETM() and CLEARM()
SETM()and CLEARM() can also be programmed independently of a synchronized action.
See Chapter "Set/delete wait markers: SETM CLEARM"
Example
Channel called "MACHINE" is to contain channel number 1,
channel called "LOADER" is to contain channel number 2:
DEF INT MACHINE=1, LOADER=2
The variables are given the same names as the channels.
The statement START is therefore:
START(MACHINE)
Job planning
Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
1.13 Program coordination (INIT, START, WAITM, WAITMC, WAITE, SETM, CLEARM)
CAUTION
Flexible NC programming
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