Siemens SINUMERIK 840D sl Function Manual page 878

Synchronous Spindles (S3)
14.1 Brief description
Speed/acceleration limits
In synchronous mode, the speed and acceleration limit values of the leading spindle are
adjusted internally in the control in such a way that the following spindle can imitate its
movement, allowing for the currently selected gear stage and effective speed ratio, without
violating its own limit values.
For example, the LS is automatically decelerated to prevent the FS from exceeding the
maximum speed in order to maintain synchronism between the spindles.
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Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions