Siemens sinumerik 840D sl Function Manual page 829

Detailed description
2.1 General functionality
While branches and check structures are invalidated by a search through all blocks (block
start) when part programs are interpreted in ASCII format (active as default), a branch is
made directly to the destination block in a preprocessed part program.
The runtime differences between branches and check structures are thus eliminated.
Example of a preprocessing runtime:
Runtime reduction by 30% with active compressor
DEF INT COUNTER
Target: G1 G91 COMPON
G1 X0.001 Y0.001 Z0.001 F100000
COUNTER=COUNTER +1
COUNTER=COUNTER -1
COUNTER=COUNTER +1
IF COUNTER<= 100000 GOTOB TARGET
CPU time intensive programs and programs with symbolic names are processed faster.
Runtime-critical sections (e.g. continuation of processing after deletion of distance-to-go or
preprocessing stop in cycles) can be processed faster.
If the interrupt routine is available as a preprocessed cycle, processing can be continued
more rapidly after the program interrupt.
8
Special functions: Preprocessing (V2)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0