Siemens SINUMERIK 840Di sl Programming Manual page 280

Feedrate Control and Spindle Motion
7.2 Traversing positioning axes (POS, POSA, POSP, FA, WAITP, WAITMC)
Traveling with POSA[...]=
The axis indicated in square brackets is traversed to the end position. The block step enable
or program execution is not affected by POSA. The movement to the end position can be
performed during execution of subsequent NC blocks.
Caution
Internal preprocessing stop
If a command, which implicitly causes a preprocessing stop, is read in a following block, this
block is not executed until all other blocks, which are already preprocessed and stored have
been executed. The preceding block is halted in exact stop (as with G9).
Traveling with POS[...]=
The next block is only executed when all axes programmed under POS have reached their
end positions.
Traveling with POSP[...]=
POSP is deployed especially for programming oscillating motions, see
/PGA/Programming Manual Advanced; "Asynchronous Oscillation"
Wait for end of travel with WAITP(...)
After WAITP, assignment of the axis to the NC program is no longer valid; this applies until
the axis is programmed again. This axis can then be operated as a positioning axis through
the PLC, or as a reciprocating axis from the NC program/PLC or HMI.
Block change in the braking ramp with IPOBRKA and WAITMC(...)
An axis is only decelerated if the marker has not yet been reached or if a different search
criterion prevents the block change. After a WAITMC, the axes start immediately if no other
search criterion prevents block change.
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Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Fundamentals