Siemens sinumerik 840D sl Function Manual page 614

Several couplings
A master can be assigned to each slave axis to produce several couplings. In a simple case,
the couplings are mutually independent, i.e. each axis is involved in only one coupling. An
example of this is a gantry axis with a master-slave coupling on each side.
Figure 2-12
One master, several slaves
It is also possible to configure master-slave couplings where one axis is the master axis for
several couplings. In this example, axis 1 is the master axis for coupling 1 and coupling 2.
Please note:
Figure 2-13
The torque controller for coupling 1 attempts to maintain the same torque between axis 1
and axis 2 by writing a speed setpoint to axis 1 and axis 2. The torque controller for coupling
2 also tries to maintain the same torque between axis 1 and axis 3. Both controllers would
write speed setpoints to axis 1.
In order to ensure a stable system, both controllers must be parameterized so that the
controller output is added only to the slave axes (axis 2 and axis 3) but not to the master axis
(axis 1). This is achieved by setting the following machine date to 1 (controller output to
slave axis only) for both couplings:
Special functions: Speed/Torque Coupling, Master-Slave (TE3)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0
Independent master-slave couplings
One master, two slaves
Detailed description
2.2 Speed/torque coupling (up to SW 5.x)
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