Rockwell Automation GMLC Reference Manual - Manual (Page 265)

Publication GMLC-5.2 - November 1999
228 Motion Blocks
The vector speed of the selected axes is equal to the specified speed in the
position units of the X axis per second or percent of the maximum speed
of the X axis. Likewise the vector acceleration and deceleration
(trapezoidal profile) is equal to the specified acceleration/deceleration in
the position units of the X axis per second
2 or percent of the maximum
acceleration of the X axis. The deceleration rate is always the same as the
acceleration rate and cannot be changed while the move is in progress.
Bad Arcs
Unfortunately, radius arc circular interpolation allows you to enter
dimensions that are non-commensurate—values that do not describe a
real circle or arc. Interpolate Axes blocks of this nature cause a Bad Arc
runtime fault (Runtime_fault = 27) when you execute the program. See
Runtime Fault under the System Variables chapter in this manual for more
information on runtime faults.
For example, the Interpolate Axes block parameters, shown below, cause
a Bad Arc runtime fault when you execute the block, because the arc
endpoint (
∆
X = 21.6,
∆
Y = 17.9) does not lie on the circle whose center is
(
∆
X = 14.1,
∆
Y = –5.1).