Retrace Support; General; Block Search With Calculation On Contour - Siemens SINUMERIK 840D sl Function Manual

TE7: Continue machining at the contour (retrace support) - 840D sl only

19.6 Retrace support

19.6 Retrace support
19.6.1

General

Retrace support refers to the entire operation from initiation of retracing through the interface
signal DB21, ... DBX0.2 = 1 (start machining continuation) up to to the continuation of the part
program processing of the programmed contour.
Requirement
In order for retrace support to function, the retrace mode, launched by means of the request
for reverse travel, must be active in the channel:
DB21, ... DBX32.1 = 1 (retrace mode active)
(See Section "Functional sequence (principle) (Page 702)")
Subfunctions
The two essential subfunctions of retrace support are the standard NC functions:
● Block search with calculation on contour
● Repositioning on the contour via shortest route (REPOS RMN)
19.6.2

Block search with calculation on contour

Function
The block search with calculation on the contour initiated implicitly by RESU within the
framework of the retrace support has the following tasks:
● Set the program pointer on the part program block on which repositioning was done with
the help of Reverse / Forward travel
● Calculates the axis positions on the basis of the programmed traversing blocks from the
start of the part program to the target block
● Collates the instructions programmed from the start of the part program to the target block,
which are executed in the action block. These include:
– Auxiliary functions
– Tool change
– Spindle functions
– Feedrate programming
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Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions