Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 380)

Axis Motion
Chapter 12
12-8
Figure 12.5
Results of An Arc Programmed with Radius Command, Example 12.5
R-18 start
point
Arc 1
R18
end point
Arc 2
Z
40
25
X
12147-I
Important: Any axis that is not specified when programming a circle
remains at its current axis position value. This results in the end point of
an arc having the same coordinate value as the start point of the arc for that
axis.
If you do not specify the end point of the arc, or if the end point is the same
as the start point, two different results are possible:
if you use I and/or K to program the arc center, a full circle is made
if you use R to program the radius of the arc, no arc is made (the control
does not move either axis)
Example 12.6
Arc End Points Same as Start Points
Arc 1-Full Circle Arc 2-No Motion
G02I-5.K5.F.1; G02R10.F.1;
or or
G02X15.Z5.I-5.K5.F.1; G02X10.Z5.R10.F.1;