Siemens SINUMERIK 840D sl Function Manual page 703

5. Select forward travel (optional):
For forward travel, reverse travel must be deselected via PLC interface signal:
DB21, ... DBX0.1 = 0
6. Forward travel (optional):
The contour is traversed in the RESU working plane in the forward direction with NC start.
7. End forward travel (optional):
Once the required program continuation point on the contour has been reached, forward
travel is ended using NC stop.
8. Retrace support:
Continue machining is initiated via PLC interface signal:
DB21, ... DBX0.2 = 1 (start retrace support)
For retrace support, RESU automatically selects the original machining program and
launches a block search with calculation as far as the program continuation point.
9. Continuation of part program machining:
Part program processing continues at the program continuation point in accordance with
the "Block search with calculation" standard function when two NC start commands occur
one after the other.
The first NC start command processes the action blocks. Retrace support ASUB
"CC_RESU_BS_ASUP.SPF" is initiated when the last action block is reached:
DB21, ... DBX32.6 = 1 (last action block active)
To ASUB (see Section "RESU-specific part programs (Page 712)").
The second NC start command processes the approach block before part program
processing is resumed.
Note
Points 3 to 8 can be repeated as often as required.
Following retrace support, a new reverse travel is possible up to a maximum of the last
program continuation point.
Special functions
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
TE7: Continue machining at the contour (retrace support) - 840D sl only
19.2 Function description
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