Rockwell Automation Publication MOTION-RM003I-EN-P - February 2018 333
Timebase determines the length over which the Average Velocity is computed.
The greater the Average Velocity Timebase value, the better the speed resolution,
but the slower the response to changes in speed.
The Average Velocity resolution in Position Units per second may be calculated
using this equation.
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 one Coarse Update Period
defined by the associated Motion Group Object.
Tag access supported but value is valid only when Auto Tag Update of the Motion
Group Object is enabled.
Actual Velocity
Usage Access T Data
Type
Default Min Max Semantics of Values
Required - All
Get/
GSV
T REAL - - - Position Units / Sec
Tag access is supported but the
value is valid only when Auto Tag
Update of the Motion Group
Object is enabled.
The Actual Velocity attribute is the current instantaneously measured speed and
direction 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 floating point value—the sign (+ or -) depends on
which direction the axis is currently moving. Its resolution does not depend on the
Averaged Velocity Timebase, but rather on the conversion constant of the axis and
the fact that the internal resolution limit on actual velocity is 1 feedback count per
coarse update.
Tag access supported but value is valid only when Auto Tag Update of the Motion
Group Object is enabled.
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