Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 548)

Dresser/Wheel Radius Compensation
Chapter 15
15-60
If necessary, the control decreases the number of available re-traceable
blocks until either there are sufficient set-up buffers available to
successfully execute the current program, or until there are no more block
retrace blocks left. The control displays a message on line 2 of the CRT if
it has to eliminate some of the block retrace blocks.
We recommend that you use as few set-up buffers as possible for block
retrace. The larger the number of look-ahead blocks that the control has
available to set up future part program motion requests, the more
efficiently the control executes programs. We recommend that the number
of set-up buffers available to the block retrace feature be kept as low as
possible.
Error detection for dresser/wheel radius compensation blocks can be
separated into three categories:
Backwards motion detection
Circular departure too small
Interference
Backwards Motion Detection
The compensated path is parallel to but in the opposite direction of the
programmed path.
Figure 15.53
Typical Backwards Motion Error
Programmed
Path
A
Compensated
Path
Compensated path
motion opposite of
programmed path
C B
D
A’ D’
B’ C’
12143-I
15.8
Error Detection