Siemens SINUMERIK 840D sl Function Manual page 355

If the wait marker for a channel to be synchronized is missing, braking will be started. During
braking, a check is made in each interpolator clock cycle as to whether the still missing wait
markers for the channels to be synchronized have arrived in the meantime. In this case, a
further acceleration to the path velocity is made and machining continues:
Figure 6-2
If the path velocity has been braked to zero before the expected markers of the channels to
be synchronized have arrived, the machining stops until the missing markers have arrived.
When the last expected marker arrives, acceleration resumes from standstill to the path
velocity:
Figure 6-3
Block change in the braking ramp
If the IPOBRKA (block change possible in the braking ramp) motion criterion is active, the
arrival of the wait marker causes an instantaneous switch to the next block and the axes started.
If the marker has not yet been reached or some other motion criterion prevents the block
change, braking continues.
Example: Conditional wait in path controlled operation
The example is schematic and shows only those commands that are relevant to the
synchronization process.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Change of the path velocity for the conditional waiting with WAITC: The last wait marker
arrives during the braking
Change of the path velocity for the conditional waiting with WAITC: The last wait marker
arrives after the braking
K5: Channel synchronization, axis interchange
6.1 Channel synchronization
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