Siemens SINUMERIK 802D sl Function Manual page 76

Travel to fixed stop (F1)
5.2 Functionality
Selection
The NC detects when preparing the block that the function "Travel to fixed stop" is selected
via the command FXS[x]=1 and signals the PLC via the IS "Activate travel to fixed stop" that
the function has been selected.
If MD37060 FIXED_STOP_ACKN_MASK (register PLC acknowledgments for travel to fixed
stop) is set accordingly, the NC waits for acknowledgment by the PLC through IS "Activate
travel to fixed stop".
The programmed target position is then approached from the start position at the
programmed velocity. The fixed stop must be located between the start and target positions
of the axis/spindle. Any programmed torque limit is effective from the block start, i.e. the
fixed stop is also approached at a reduced torque. Allowance for this limitation is made in the
NC through an automatic reduction in the acceleration rate.
If no torque was programmed in the block or since the beginning of program, the value
entered in the axis-specific MD37010 FIXED_STOP_TORQUE_DEF (default setting for
clamping torque) applies.
Fixed stop reached
As soon as the axis comes into contact with the mechanical fixed stop (workpiece), the
closedloop control in the drive raises the torque so that the axis can move on. The torque
rises up to the programmed limit value and then remains constant.
The status "fixed stop reached" can, depending on the MD37040
FIXED_STOP_BY_SENSOR (fixed stop recognition by sensor), be determined in the
following ways:
● FIXED_STOP_BY_SENSOR = 0
● FIXED_STOP_BY_SENSOR = 1
● FIXED_STOP_BY_SENSOR = 2
Internal processes
Once the NC has detected the "Fixed stop reached" status, it deletes the distancetogo and
the position setpoint is made to follow. The controller enabling command remains active.
The PLC is then informed of the state by means of IS "Fixed stop reached".
If MD37060 FIXED_STOP_ACKN_MASK is set accordingly, then the NC waits for
acknowledgment by the PLC in the form of IS "Acknowledge fixed stop reached".
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The status "fixed stop reached" is active when the axis-specific contour deviation (=
difference between actual and expected following error) has exceeded the value of the
MD37030 FIXED_STOP_THRESHOLD (threshold for fixed stop recognition).
External sensor transmits "Fixed stop reached" status to NC via the PLC by means of IS
"Sensor fixed stop".
The status "Fixed stop reached" is provided if either this status has been determined by
the contour monitoring function or if the external sensor signals this status in response to
signal edge change 0 → 1.
Turning, Milling, Nibbling
Function Manual, 11/2012, 6FC5397-1CP10-5BA0