Siemens SIMATIC S5 Manual page 65

Machining Programs and their Structure
Each M-function is output at the beginning of the execution of a statement (traversing job or
dwell time) and remains valid until the next M-function at the start of the next statement (tra-
versing job or dwell time) containing an M-function is output.
In the control program, M-functions can be used to trigger user- specific actions, e.g. the switch-
ing on and off of plant during the traversing movement of the axis.
If several statements with consecutive different M-functions are programmed with the help of the
"flying change" (G I O) the new M-function is output after the transition.
If statements without M-functions are programmed at the beginning of a machining program,
function is executed. If a machining program does not contain any M-functions except for M02,
then M255 will be output during the whole program.
Examples
N05 G91 M-function not feasible, output M255
N05G91
N1 OG74
N15G24F3
N30G57
N45G20
N50 G74 M20
N60X500F1 OOM30
N65 G26
N75M02
Certain special factors apply to M02 and MOO as follows:
specified in the final statement of the machining program. Following this, no further statements
can be appended to the machining program. The final statement can simply consist of the N-
function and M02. If M02 is specified in a traversing statement, no further M-function can be
specified in the statement.
MOO
MOO means "programmed halt". A statement with a MOO has the effect that the next programmed
traversing movement (X-function or G74) or dwell time (G04) is only executed following an enter
command. Offsets (e.g. G57 or G43) and switchovers (e.g. G91 ) following an MOO and before a
traversing movement or dwell time are, however, executed before the halt.
N30 ! X200 F500
N50G57 ! X200 F500
2 - 4 8
M-function not feasible, output M255
output M255
M-function not allowed, output M255
output M 10
M-function not feasible, output Ml O
output Ml O
M-function not allowed
output M30
M-function not feasible, output MEKI
output M60
final statement/program end
(! = break point)
program halt before the dwell time
program halt before the traversing movement
break point after the zero offset
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