Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 709)

In-process Dresser
Chapter 21
21-3
In-process dresser offsets cannot be modified, activated, or deactivated by
the programmer. As long as the in-process dresser remains active, any
generated dresser offset also remains active. Once the in-process dresser is
deactivated, the control cancels any currently active in-process dresser
offset. If the in-process dresser offset is to be maintained, you must take
steps to make sure the correct wheel length or radius offset numbers are
activated as described on page 21-6.
In-process offset axis motion is automatically generated as the wheel is
positioned about the part and the in-process dresser changes the wheel
diameter. This offset is updated every 20ms as the wheel is dressed.
We recommend the use of dresser/wheel radius compensation (G41 or
G42) during grinding operations when the in-process dresser is active.
This prevents drastic changes to wheel path at corner intersections by
generating a circular transition around the corner. This circular transition
forces the generated length compensation move to be tangent to the
generated circular transition.
The in-process dresser feature does not have any effect on the grinding
wheel radius if dresser/wheel radius compensation is active. In-process
dresser offsets are only length type offsets. This can cause some slight
inaccuracies on more complex grinding contours. If changes in wheel
radius must be considered by the in-process dresser, you should use radius
offset 33. This offset is updated with one-half the new wheel diameter
when the in-process dresser is deactivated. The more frequently the
in-process dresser is deactivated, the more accurate the value of radius
offset number 33. See “Maintaining Dresser Offsets” on page 21-6 for
details on radius offset number 33.