S9: Setpoint Switchover; Brief Description - Siemens SINUMERIK 840D Function Manual

S9: Setpoint switchover

11.1

Brief description

Function
The "Setpoint switchover" function is required if only one motor is to be used to drive several
axes/spindles. For example, for milling heads, where the spindle motor is to be used to drive the
tool as well as to orientate the milling head.
Requirements
The following conditions must be fulfilled so that the setpoint can be switched over:
● All of the axes involved in the setpoint switchover are at a standstill
● No sign-of-life error and no errors are active on PROFIBUS
● None of the following functions in the axis with drive control are active:
– Reference point approach
– Measuring
– Travel to fixed stop
– Function generator
– Star/delta switchover
– Parameter set switchover
Position control loop
The drive train, and therefore also the position control loop, are disconnected while the setpoint
is being switched over. In order to avoid instability, the setpoint is only switched over at standstill
- and once all controller enable signals have been cleared (deleted).
When using a single drive, only one control loop can be closed at the same instant in time. Axes
without drive control are operated with open position controller and tracked positions.
Note
Vertical axes
The controller enable signals for all of the axes involved are automatically withdrawn by the
control for the duration of the switchover. Axes without drive control are not in closed-loop
control. Therefore, a brake control must be implemented for vertical axes.
Axes and spindles
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