Three Position Step Control Algorithm; Table 5-29 Procedure For Displaying The 3Pstep Motor Position - Honeywell UDC 3300 Product Manual

5.16 Three Position Step Control Algorithm

Introduction
Estimated motor
position
Accurate motor
position
Displaying the motor
position
Power-up output
182
The Three Position Step Control algorithm (Loop 1 only) allows the
control of a valve (or other actuator) with an electric motor driven by two
controller output relays; one to move the motor upscale, the other to move
it downscale, without a feedback slidewire linked to the motor shaft.
Accutune SP or SP+PV tuning does not function with this algorithm.
Accutune TUNE will operate with this algorithm.
Models DC330X-EE-XXX-X0, DC330X-AA-XXX-X0
The Three Position Step control algorithm provides an output display
(OUT) which is an estimated motor position since the motor is not using
any feedback. Although this output indication is only accurate to a few
percent, it is corrected each time the controller drives the motor to one of
its stops (0 % or 100 %).
It avoids all the control problems associated with the feedback slidewire
(wear, dirt, noise). When operating in this algorithm, the estimated "OUT"
display is shown to the nearest percent (i.e. no decimal).
Models DC330X-EE-XXX-X2, DC330X-AA-XXX-X2
In the event that an accurate and repeatable indication in motor position is
required, Position Proportional model's slidewire input can be used to
read the motor position and display it on the lower display as "POS" while
still operating in the Three Position Step control mode.
The slidewire must be calibrated for this to operate correctly.
Table 5-29 lists the procedure for displaying the motor position.
Table 5-29 Procedure for Displaying the 3PSTEP Motor Position
Step Operation
1 Access the
displays
When the controller powers up after a power outage, the position of the
motor will correspond to whatever was configured at the Control Set Up
function prompt PWR OUT, selection LAST or F'SAFE. Refer to Section
4.10, Table 4-9 for definition of each selection.
UDC 3300 Controller Product Manual
Press
until you see:
LOWER
Upper Display
DISPLAY
Lower Display
POS =
slidewire connected
or
OUT =
position when no slidewire exists
Action
The PV value
3PStep motor position with
Estimated 3PStep motor
4/00