Siemens SIMATIC FM 353 Manual page 302

Writing Traversing Programs
Influence of M function on block change on-the-fly
Machine data can specify the output time for M functions:
S M function is output before or after positioning with a block change
M-function output and positioning proceed in alternation.
− M function output before positioning causes exact-positioning response in
the preceding block.
− M function output after positioning causes exact-positioning response within
the block.
S M function is output during positioning
M-function output and positioning proceed simultaneously.
The following figure shows a sample program with M function output "during
positioning".
/
10
15
20
V
N5
1
M No.
10
1 − Output of M10 is not position-dependent, since no relevant position for a position
dependent M function is present.
2 − At the block change from N5 to N10, output is prepared. The axis the M function does
not proceed until the actual position has reached the programmed position of N5.
3 − If two M functions are programmed in a traversing block, the first M function is output
depending on position, followed by the second M function.
4 − The change signal for M97 or M98 is output with the G64 block transition (digital
output) if the actual position has reached the programmed position of the block.
The actual position runs behind the set position (difference = overtravel).
10-20
N G1 G2 G3
5 90
60
N10 N15
2
3
10 000 20 000
20 30
X/t F M1
10 000 100 00 10
20 000 20
30 000 30
40 000
N20
4
30 000
40 97
FM 353 Stepper Drive Positioning Module
M2 M3 D
40
97
X
40 000
6ES7 353-1AH01-8BG0
J