Siemens SINUMERIK 840D sl Function Manual page 913

Activate coupling with COUPONC
When the coupling is activated, the following spindle is accelerated, as before, to the leading
spindle speed through application of the coupling factor. If the following spindle is already
rotating (M3, M4) when the coupling is activated, it continues with this motion after coupling.
Deactivate coupling
If the coupling is deactivated, the following spindle continues to rotate at the speed
corresponding to the sum of both speed components. The spindle behaves as if it had been
programmed with the speed and direction transferred from the other spindle. When
deactivating, there are no differences to the previous behavior.
Differential speed
A differential speed results from renewed programming of the following spindle (in the
example S2=... ) or M2=3, M2=4 in speed control mode during an active synchronous
spindle coupling or by adopting the speed of the following spindle with COUONC.
Condition:
Speed S... must also be re-programmed with direction of rotation M3 or M4. Otherwise alarm
16111 "Channel% Block% Spindle% No speed programmed" is displayed.
Read offsets of following spindle
The current offset always changes when a differential speed is programmed. The current
offset can be read at the setpoint end with $AA_COUP_OFFS[Sn] and at the actual value
end with $VA_COUP_OFFS[Sn].
The last offset programmed returns the variable $P_COUP_OFFS[Sn].
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.
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
S3: Synchronous spindle
14.4 Special features of synchronous mode
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