Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 335)

Publication 1784-UM003A-EN-P – June 2003
Motion Object Attributes 327
Velocity Servo with Velocity Servo
Drive
This configuration provides velocity servo control using an external velocity
loop servo drive. In this configuration the servo module does not close the
velocity loop, but rather the drive does. Synchronous input data to the servo
loop includes Velocity Command and Velocity Offset. (Torque Offset is
ignored.) These values are updated at the coarse update rate of the associated
motion group. The Position Command value is derived directly from the
output of the motion planner, while the Velocity Offset value is derived from
the current value of the corresponding attributes. The Velocity Offset attribute
can be changed programmatically via SSV instructions which, when used in
conjunction with future Function Block programs, provides custom “outer”
control loop capability.
Figure 13.11 Velocity Servo with Velocity Servo Drive
Output
Limit
Position
Accum-
ulator
Σ
Velocity
Command
(Coarse)
Fine
Interpolator
Velocity
Command
16-bit
Encoder
Counter
Marker
Latch
Velocity
Servo
Drive
Ch Z
Marker
Input
Marker
Event
Handler
Regist.
Event
Handler
Watch
Event
Handler
Watch
Event
Registration
Event
Homing
Event
Regist.
Latch
Registration
Input
Acc
FF
Gain
d/dt
Σ 16 Bit
DAC
Position
Feedback
(Coarse)
Low
Pass
Filter Output
Scaling
Friction
Comp.
Output
Offset
&
Servo
Polarity
Servo
Output
Level
Output
Filter
BW
Encoder
Polarity
Velocity
Offset
Watch
Position
Torque
Offset
Σ
AQB
Encoder
Ch A/B
Encoder
Input
Motor
Servo Config = Velocity Servo