Rockwell Automation WebPak 3000 DC Drive Application Workbook Version 1.1 - Manual (Page 67)

Configuring the Position Outer Loop 11-5
The output of the SCALE block is TEN / DANCER FDBK SCALED (P.489). See the following
examples for more information on setting up the SCALE block.
11.3 The Position PI Output
Refer to figure A.16 in appendix A of the software manual (D2-3444) as you configure
the position
PI output.
The output of the PI block is POSITION VERNIER (P.241), which is used as a trim signal
on the speed loop when CASCADE is selected, or as the input to the speed loop limits
when PARALLEL is selected as configured by OCL TYPE (P.818).
The amount of speed loop trim is set by the HI and LO limits of the PI block, which
would nominally be configured at 10% by setting POS PI LIMIT (P.235) to 409.5.
However, product characteristics, such as modulus of elasticity, can require more or
less than 10% trim.
Note that POSITION VERNIER (P.241) will be a proportional or incremental trim of line
speed, dependent on the configuration of OCL PROP TRIM GAIN (P.812). Refer to section
3.3, Speed Mode Select.
þ
To configure the position PI output:
▲
Set POS PI LIMIT (P.235) to set the HI and LO output limits of the PI block.
Setting Up the Scale Block
The setting for TENSION FDBK MIN (P.852) and TENSION FDBK MAX (P.851) depend on
the characteristics of the dancer feedback signal.
The output of the SCALE block will go from 0 to 4095 counts as the dancer goes
from zero storage to maximum storage. Typically, the dancer feedback signal will be
zero at zero storage and maximum at maximum storage.
Example 1
If the dancer feedback signal can be set, by external calibration and/or analog input
calibration, so that
TENSION / DANCER FDBK (P.493) is 0 to 10 volts as the dancer
moves from minimum to maximum position, then TENSION FDBK MIN (P.852) would
be set to 0, and TENSION FDBK MAX (P.851) would be set to 4095.
Example 2
The dancer feedback signal (analog input) goes from 1.0 volts to 8.0 volts as the
dancer moves from minimum to maximum position, and
TENSION / DANCER FDBK
(P.493), which is the digitized equivalent, goes from 409 to 3276. In this example,
TENSION FDBK MIN (P.852) would be set to 409 and TENSION FDBK MAX (P.851) would
be set to 3276.
Range: 0 to 4095 COUNTS (4095 = TOP LINE SPEED ) P.235 = COUNTS