Actual velocity, Command velocity – Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual User Manual
Page 282
Publication 1784-UM003A-EN-P – June 2003
274 Motion Object Attributes
For example, on an axis with position units of inches and a conversion
constant (K) of 20000, an averaged velocity time-base of 0.25 seconds results
in an average velocity resolution of:
The minimum Average Velocity Timebase value is Coarse Update period
defined by the associated Motion Group Object. See the Motion Configuration
Attribute section of this document for more information on setting the
Averaged Velocity Timebase and the Conversion Constant parameters.
Actual Velocity
Actual Velocity is the current instantaneously measured speed of an axis, in the
configured axis Position Units per second. It is calculated as the current
increment to the actual position per coarse update interval. Actual Velocity is a
signed value—the sign (+ or -) depends on which direction the axis is currently
moving.
Actual Velocity is a signed floating-point value. Its resolution does not depend
on the Averaged Velocity Timebase, but rather on the conversion constant of
the axis and the fact that the GSV/SSV resolution limit on actual velocity is 1
feedback counts per coarse update.
Command Velocity
Command Velocity is the commanded speed of an axis, in the configured axis
Position Units per second, as generated by any previous motion instructions. It
is calculated as the current increment to the command position per coarse
update interval. Command Velocity is a signed value—the sign (+ or -)
depends on which direction the axis is being commanded to move.
Command Velocity is a signed floating-point value. Its resolution does not
depend on the Averaged Velocity Timebase, but rather on the conversion
constant of the axis and the fact that the GSV/SSV resolution limit on
command velocity is 0.00001 feedback counts per coarse update.
⎥⎦
⎤
⎢⎣
⎡
nit
Position U
Counts
Feedback
K
x
[Seconds]
Timebase
Velocity
Averaged
1
Minute
Inches
012
.
0
Second
Inches
0002
.
0
20000
x
25
.
0
1
=
=
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Actual Velocity
REAL
Position Units / Sec
GSV/SSV Access
Attribute Name
Data Type
Values
GSV
Command Velocity
REAL
Position Units / Sec