Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 416)

Axis Motion
Chapter 12
12-44
Spindle Speed during Rapid Traverse
During rapid moves while in G96 mode, spindle speed changes in one of
the following ways:
the spindle speed changes constantly as the relative position of the CSS
axis is changed
or
the control calculates the total change in spindle speed (if any) that
would be made from beginning to end of the rapid move and uses that
spindle speed for the entire rapid move.
Your system installer selects the spindle speed control type in AMP.
Displayed Spindle Speed during CSS
Regardless of whether you are in G97 or G96 mode, the CRT display
shows the current spindle speed in RPM following the S--word. This is
also true during CSS. The display shows the actual spindle RPM, not the
surface speed.
CSS R-word Programming
The optional R-word lets you specify a surface footage value to be applied
at a point other than the current axis position. The R-word defines the
incremental distance from the current wheel edge to the spindle centerline.
The sign of the R-word defines on which side of the spindle centerline the
tool tip is positioned.
The R-word is recognized only in a G96 block; its value is valid as long as
CSS mode is active and may only be changed when a G96 is programmed
in the block.
If you change the S-word (surface footage) while in G96 mode and if an
R-value was previously programmed in a G96 block, the R-value is not
cancelled.
Important: An R0 and no R-word do not mean the same thing. An
R-word of zero means that the spindle centerline is the tool tip position.
No R-word means to use the current position.