Siemens SINUMERIK 840C Installation Instructions Manual page 1019

12 Functional Descriptions
12.24.2 Functional description
The operating principle is explained below on the basis of an example (showing sleeve being
pressed onto workpiece).
Selection
The axis traverses at the programmed velocity towards to the programmed position,
commencing at the start position. The axis behaves like a normal NC axis during this process.
The current limitation on the actuator is now activated.
As soon as the axis presses against the mechanical fixed stop (workpiece), the control on the
drive will attempt to increase the torque by raising the current setpoint. This, however, has
already been limited to a specific value beforehand (NC MD 1144*, Switchover current
setpoint).
The "Fixed stop reached" state can be detected by two different methods, depending on the
setting in NC MD 1804*.3 "Sensor signal PLC for travel to fixed stop".
NC MD 1804*.3 = 1 External sensor sends "Fixed stop reached" signal to NC via the PLC.
NC MD 1804*.3 = 0 The "Fixed stop reached" state is established when the following error
has exceeded the value set in NC MD 1280* "Following error threshold
for travel to fixed stop".
Once the "Fixed stop reached" state has been detected by the NC, the distance to go is
deleted and the axis switched to follow-up mode.
If the programmed end position is reached before the "Fixed stop reached" state is detected,
the alarm "Fixed stop not reached" is output.
The NC performs a block change, but leaves a setpoint applied to the drive actuator so that
the clamping torque is effective.
The clamping torque can be changed while "Fixed stop" is active via programming G222 axis
> P... or through a direct input in the SE data display "Travel to fixed stop".
12–244
Actual position after
"Travel to fixed stop"
"Start travel
to fixed stop"
position
Progr.
end position
© Siemens AG 1992 All Rights Reserved
12.93
Start position
6FC5197- AA50
SINUMERIK 840C (IA)