Program Execution And Direction Of Processing - Siemens SIMATIC FM 353 Manual

Writing Traversing Programs
10.2

Program execution and direction of processing

Forward processing
As a rule, programs are processed by ascending block number.
Reverse processing
If programs are processed in reverse, the effects of commands must be taken into
account in the programming:
S Commands are modal (G90, G91, G60, G64, G30 − G39)
S Active tool offset (G43, G44, D0 − D20)
S Change of coordinate systems via G87, G88, G89.
For these reasons, a distinction can be made between forward processing and re-
verse processing, in terms of both geometry and block transition response.
10.3 Block transitions
Overview
This chapter describes the influence of certain commands on block transitions.
Exact positioning - G60
G60 mode is overlaid with G50 and G88 to G89 (force block change on-the-fly).
The program advances to the next block when the target range is reached.
The influence of M functions is as indicated in machine data item MD32.
Output of M function before positioning
Case 1
10-16
V
N
i
M
É É É É É É É É É É
É É É É É
N
i+1
t
t
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0