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Programming of Traversing Blocks
4.11.8 Flying actual-value setting (G87, G88, G89)
The "Flying actual-value setting" function is triggered by a fast input, the block change taking
place on the fly and the actual value being at the same time set to a new measure. In addition,
it is possible to read out the actual value saved at the moment of arrival of the fast input
(command: "Read out flying measured value"). The fast input must be programmed with the
"Flying actual-value setting" function.
The rapid input must be preset in MD 15 of the programmed axis.
Programming:
N10 G90 G77 X100.000 FX4000.00
N15 G89(G88) X50.000 FX2000.00
N20 G90 X300.000 FX4000.00
N25 G87 X400.000 FX4000.00
F
N10
X
E programmed fast input
E
N10
0
50
100
Measuring system
displaced
Flying block change from N10 to N15, G89 effecting a movement in positive direction and
G88, a movement in negative direction, at the programmed velocity of N15.
The axis traverses in the specified direction until a positive edge change takes place at the
fast input. This triggers the following reactions:
– Flying block change and immediate processing of block N20
– Flying actual-value setting to the block position of N15 and, therefore, displacement of
the measuring system
– Saving of the current encoder actual value
The programmed position in block N20 refers to the displaced measuring system.
Flying block change from N20 to N25, G87 cancelling the measuring-system displacement
and effecting a reference-measure programming to the block position of N25, as G90 is
still active.
4 – 36
N15
N20
E
N15
150
200
250
300
350
N20
0
50
100
150
©
Siemens AG 1997 All Rights Reserved
N25
Inversion of the
direction
t
t
N25
Measuring
x
system
400
200
250
300
350
400
6ZB5 440-0VU02
WF 723 C (Programming Guide)
04.97
x
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