Siemens SINUMERIK 840D sl Function Manual page 899

Display differential speed
The programmed difference component is displayed as the speed setpoint for the
programmed differential speed (in our example, corresponds to 100 rpm).
The actual speed refers to the motor speed. In the example, the actual speed is 500 rev/min
* (-1) + 100 rpm = -400 rev/min.
IS NCK to PLC
Following spindle in speed-controlled operation
The IS "Spindle in setpoint range" (DB31, ... is set for the following spindle by the NCK if the
programmed speed (see example above N26 with M2=3 S2=100) is reached. If a differential
speed is programmed and not enabled by the PLC, this VDI interface signal is not set.
Even if a differential speed has been programmed, the following spindle remains under
position control if this is required by the coupling.
Note
The axial VDI interface signal NCK → PLC IS "Superimposed motion" is set (DB31, ...
DBX98.4) when setpoints in addition to the coupling setpoints are created by differential
speed programming.
Actual direction of rotation CW (DB31, ... DBX83.7)
The IS "Actual direction of rotation CW" (DB31, ... DBX83.7) refers to the resultant direction
of motor rotation.
IS PLC to NCK
Influence on following spindle via PLC interface
The effect of the axial VDI interface signals on the following spindle with differential speed in
speed control mode is described below.
Delete distance to go / Spindle Reset (DB31, ... DBX2.2)
The programmed differential speed and direction of rotation can be terminated by IS "Delete
distance-to-go/Spindle Reset" (DB31, ... DBX2.2). To delete the programmed speed only, it
is possible to set IS "Delete S value" (DB31, ... DBX16.7).
Resynchronize spindle 1/2 (DB31, ... DBX16.4 and 16.5)
The IS "Resynchronize spindle 1/2" (DB31, ... DBX16.4/16.5) are not locked. Any positional
offset is not compensated automatically by the coupling.
Invert M3/M4 (DB31, ... DBX17.6)
The IS "Invert M3/M4" (DB31, ... DBX17.6) only inverts the speed component additionally
programmed for the following spindle.
The motion component generated by the synchronous spindle coupling remains unaffected.
Extended Functions
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Synchronous Spindles (S3)
14.4 Special features of synchronous mode
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