Lookahead; Standard Functionality - Siemens SINUMERIK 840D sl Function Manual

B1: Continuous-path mode, Exact stop, Look Ahead
4.3 Continuous-path mode
RMBBL
RMIBL
RMEBL
RMNBL
①
②
③
4.3.4

LookAhead

4.3.4.1

Standard functionality

Function
LookAhead is a function which is active in continuous-path mode (G64, G64x) and determines
a foreseeable velocity control for multiple NC part program blocks over and beyond the current
block.
Note
LookAhead is only available for path axes, not for spindles and positioning axes.
If a part program contains consecutive blocks with very small paths, only one velocity is
reached per block without LookAhead, enabling deceleration of the axes at the end of the block
while maintaining acceleration limits. This means that the programmed velocity is not reached
at all. With LookAhead, however, it is possible to implement the acceleration and deceleration
phase over multiple blocks with approximately tangential block transitions, thereby achieving
a higher feedrate with shorter distances.
200
Repositioning at the start of the interrupted traversal block
Repositioning at the interruption location
Repositioning at the end of the interrupted traversal block
Repositioning at the next contour point
Block start N10
To the REPOS start point of the next contour point
Block end N10 / block start N20
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions