Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 382)

Axis Motion
Chapter 12
12-10
Typically you program a rotary axis in a block by itself or with linear
moves (rapid G00 or linear G01 moves). You can, however, program a
rotary axis in a block that contains circular moves (G02 or G03).
Programming in Absolute or Incremental
You can program rotary axes in absolute or incremental mode.
In absolute mode (G90), the rotary axis is programmed to angular
positions. These positions are programmed between 0
°
and 359.99
°
. The
sign given to this angular position determines the direction that the rotary
axis travels to reach the programmed angle. For example, if you program:
G90C25;
in a part program, that causes the rotary axis C to rotate to an angle of 25
°
(referenced from a position 0 determined by your system installer) and to
rotate the axis in the positive direction to reach this position. If you
program:
G90C-25;
in a part program, that causes the rotary axis C to rotate to an angle of 25
°
and to rotate the axis in the negative direction to reach this position.
In incremental mode (G91), the rotary axis is programmed to move an
angular distance (not to a specified angle as in absolute). The maximum
incremental departure depends on the programming format selected in
AMP by your system installer. The sign of the angle determines the
direction the rotary axis rotates in. For example, if the current C axis
position is 25
°
and you program the following block:
G91C50;
the C axis would rotate 50
°
in the positive direction. The new C axis
position would be 75
°
.
If the current C axis position is 25
°
and you program this block:
G91C-50;
the C axis would rotate 50
°
in the negative direction. The new C axis
position would be 335
°
.
In incremental mode (G91), programming a value greater than the rollover
amount results in the rotary axis making one or more complete revolutions.
In absolute mode (G90) you cannot program a rotary axis move greater
than the rollover amount.