Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 423)

Axis Motion
Chapter 12
12-51
In the G97 mode, the spindle revolves at the programmed RPM regardless
of the position of the grinding wheel.
For example, to revolve the spindle at 500 rpm, program:
G97 S500;
Important: In most cases, spindle motion is started and stopped by
executing an M code (typically M03 or M04 to start and M05 to stop).
Refer to the documentation prepared by your system installer.
The G97 code is modal and remains active until it is cancelled by the G96
code.
When changing from G96 to G97 mode, if an S--word is programmed in
the G97 block the spindle changes speed to the RPM value indicated by the
S--word. If no S--word is programmed in the G97 block, the control
maintains the control uses the current speed of the wheel as the spindle
RPM to be maintained.
The control is equipped to perform a part or wheel spindle orient operation.
Use this operation to rotate the part or grinding wheel to a given angle.
Typically this feature is used to orient the part or grinding wheel for
load/unload/removal operations.
Important: M19 Spindle Orientation is applied only to the spindle that is
controlled with the programmed S--word.
Two types of part or wheel spindle orients are available:
Open loop orient - The part or wheel does not use a feedback device
for this type of orient. The final destination of the part or wheel when
performing an open loop orient is determined by PAL. Typically there
is some form of hardware switch used to determine the part or wheel is
at the proper position. When the open loop orient is performed, the part
or wheel is turned at an AMP defined RPM and in an AMP defined
direction.
12.5.8
RPM Spindle Speed Mode
(G97)
12.6
Part or Wheel Spindle
Orientation (M19)