Siemens SINUMERIK 840D sl Programming Manual page 366

Fundamentals
2.14 Supplementary commands
If an anticipated event ($R3) has occurred and the status "Limit stop contacted" (system
variable $AA_FXS) is reached, then FXS must be deselected.
Program code
IDS=4 WHENEVER (($R3==1) AND ($AA_FXS[Y]==1)) DO FXS[Y]=0
FA[Y]=1000 POS[Y]=0
Fixed stop reached
When the fixed stop has been reached:
● The distance-to-go is deleted and the set position is tracked.
● The drive torque increases up to the programmed limit value FXSW, and then remains
constant.
● Fixed stop monitoring is activated within the specified window width.
Supplementary conditions
● Measurement with delete distance-to-go
"Measurement with delete distance-to-go" (MEAS command) and "Travel to fixed stop"
cannot be programmed at the same time in one block.
Exception: One function acts on a path axis and the other on a positioning axis or both act
on positioning axes.
● Contour monitoring
Contour monitoring is not performed while "Travel to fixed stop" is active.
● Positioning axes
For "Travel to fixed stop" with positioning axes, the block change is performed irrespective
of the fixed stop movement.
● Link and container axes
Travel to fixed stop is also permitted for link and container axes.
The status of the assigned machine axis is maintained beyond the container rotation. This
also applies for modal torque limiting with FOCON.
● Travel to fixed stop is not possible:
– With gantry axes
– For competing positioning axes that are controlled exclusively from the PLC (FXS must
● If the torque limit is reduced too far, the axis will not be able to follow the specified setpoint;
the position controller then goes to the limit and the contour deviation increases. In this
operating state, an increase in the torque limit may result in sudden, jerky movements. To
ensure that the axis can follow the setpoint, check the contour deviation to make sure it is
not greater than the deviation with an unlimited torque.
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be selected from the NC program).
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming