Siemens SIMATIC FM 353 Manual page 289

Notes to the example of set actual value on-the-fly
This changes blocks on-the-fly from N10 to N15, with G89 causing movement in a
positive direction and G88 causing movement in a negative direction at the speed
programmed in N15.
The axis now travels in the specified direction until a positive edge change occurs
at the digital input. This triggers the following responses:
S Block change on-the-fly and immediate processing of block N20
S Set actual value on-the-fly to the block position from N15 (50 in the example),
and resulting shift of the coordinate system
S Save current actual value.
The programmed position in block N20 refers to the shifted coordinate system.
At the block change from N20 to N25, G87 cancels the shift of the coordinate sys-
tem and causes reference-measure programming to the block position of N25.
The saved actual value can be read out with "Actual value block change."
The shift of the coordinate system is maintained until it is canceled by G87 or by a
mode change. It is possible to use the existing shift of the coordinate system in
different programs. The coordinate system can be shifted again without previously
canceling an existing coordinate system shift.
G88, G89 can be programmed multiple times. The shift in each case refers to the
original state. The software limit switches are always shifted concurrently.
If the signal change of the digital input does not occur, the axis runs until it reaches
the limit switch.
Note
The G functions G87, G88 and G89 take effect only on a block-by-block basis and
must be reselected if necessary.
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0
Writing Traversing Programs
10-7