Siemens SINUMERIK 840D sl Function Manual page 377

Fixed stop is not reached
If the programmed end position is reached,
without detecting the state "fixed stop reached",
then the internal torque limitation in the machine data:
MD37070 FIXED_STOP_ANA_TORQUE
is cancelled and the NST signal "Activate travel to fixed stop".
(DB31, ... DBX62.4) is reset.
The PLC then activates the preceding gear stage, thus deactivating the torque limitation. It
also switches on the speed control monitoring function again.
Depending on the machine data:
MD37060 FIXED_STOP_ACKN_MASK
the acknowledgement of the PLC is awaited through resetting of the NST
"Enable travel to fixed stop" (DB31, ... DBX3.1) awaited
and then a block change is executed.
Deselection
The NC detects that the function has been deselected on the basis of command FXS[x]=0
and specifies a speed or torque setpoint of "0," i.e. zero clamping torque.
Then the NC resets the NST "Activate travel to fixed stop" (DB31, ... DBX62.4) and "Fixed
stop reached" (DB31, ... DBX62.5)
D.
If torquecontrolled operation is activated, the PLC must first select the unassigned gear
stage in which the torque limitation is effective and switch the drive over to speedcontrolled
operation (a speed setpoint of "0" is applied by NC). The PLC must also deactivate the
speed controller monitoring function.
The PLC then activates the preceding gear stage, thus deactivating the torque limitation. It
also switches on the speed control monitoring function again.
Depending on the machine data:
MD37060 FIXED_STOP_ACKN_MASK
the acknowledgement of the PLC is awaited through resetting of the NST
"Enable travel to fixed stop" (DB31, ... DBX3.1) and/or
("Acknowledge fixed stop reached") (DB31, ... DBX1.1) is awaited.
The C-axis then switches over to position control mode (followup mode is terminated) and
synchronization with the new actual position takes place.
The programmed travel motion is then executed.
A block change is executed after the target position has been reached.
Basic logic functions: Travel to fixed stop (F1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Detailed Description
2.3 Travel to fixed stop with analog drives
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