Siemens SINUMERIK 840Di Function Manual page 348

Detailed Description
2.2 Travel to fixed stop with analog drives
Fixed stop is not reached
If the programmed end position is reached without the "Fixed stop reached" status being
recognized, then the torque limitation in the drive is canceled via the digital interface and IS
"Activate travel to fixed stop" (DB31, ... DBX62.4).
Depending on the machine parameter:
MD37060 FIXED_STOP_ACKN_MASK
the NC waits for the PLC to acknowledge by resetting IS
"Activate travel to fixed stop" (DB31, ... DBX3.1)
and then the block change is performed.
Deselection
The NC recognizes the function deselection via programming of the command FXS[x]=0.
Then an advance stop (STOPRE) is internally released, since it cannot be forseen where the
axis will be after deselection.
The torque limitation and monitoring of the fixed stop monitoring window are canceled.
IS "Activate travel to fixed stop" (DB31, ... DBX62.4) and "Fixed stop reached"
(DB31, ... DBX62.5) are reset.
Depending on the machine parameter:
MD37060 FIXED_STOP_ACKN_MASK
the NC waits for the PLC to acknowledge by resetting IS
"Activate travel to fixed stop" (DB31, ... DBX3.1) and/or
"Acknowledge fixed stop reached" (DB31, ... DBX1.1).
The axis will then change to position control. The followup mode of the position setpoints is
ended and a synchronization to the new actual position is carried out.
A programmed traverse motion can then be executed. This motion must lead away from the
fixed stop or else the stop or even the machine may sustain damage.
A block change is executed after the target position has been reached.
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Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Travel to Fixed Stop (F1)