PCU12005 datasheet(45/96 Pages) REDLION

45 / 96 page

Local/Remote Setpoint Transfer Modes (SPtr)

When switching from/to Local or Remote Setpoint, the response of the

controller can be programmed to act in a variety of ways.

These responses apply to changes in setpoint mode from the controller’s

front panel, User Input or Serial communications. The table summarizes the

responses for Setpoint transfer operation:

SPtr parameter

Local to Remote

Remote to Local

nor

– Output may bump.

Output may bump.

Auto

– No output bump. Process

error eliminated at rate of

integral action.

No output bump. Process

error eliminated at rate of

integral action.

trAC

– Output may bump.

Local setpoint assumes

value of Remote setpoint

(tracks). No output bump.

Note: In situations where an output bump may occur, the setpoint ramp function

(SPrP) can be used to reduce or eliminate bumping when switching setpoint

modes. The setpoint ramp feature ramps the setpoint from the old setpoint

mode to the new setpoint mode. After the initial ramp has been completed, the

active setpoint (Local or Remote) remains in the setpoint ramp mode.

Secondary Output Power Dampening (OPd2)

The output power of the secondary loop (Internal Cascade) can be

dampened (filtered) independent of the primary loop. The secondary output

power is the actual output of the controller. The primary output power

(setpoint to the secondary) is dampened by the OPdP parameter. The

secondary output power is dampened by the OPd2 parameter.

VALVE POSITIONER MODULE (8-VP)

The Valve Positioner controller must be configured to operate in either

Position Mode or Velocity Mode. Position Mode requires a slidewire

feedback signal from the valve or valve positioner. Velocity Mode does not

require a slidewire feedback signal. See

Valve Position Option, page 54, for

an overview of valve position control.

Valve Position 1 And Valve Position 2 (VPS1, VPS2)

The full closed valve position and the full open valve position are

represented by parameters VPS1 and VPS2, respectively. These values are

expressed as a percentage of the valve open position. They do not represent

slidewire resistance. Normally, for position mode control, VPS1 = 0.0% and

VPS2 = 100.0%. In some processes, it may be necessary to limit the range

over which the controller positions the valve. In such a case, VPS1 defines the

minimum open position and VPS2 defines the maximum open position. The

controller then scales the valve position values to represent 0 and 100%

output power. In this way the valve is confined to work over a smaller portion

of its total range.

Setting both parameters to 0.0% engages velocity mode control. Slidewire

feedback is not required for velocity mode. Additionally, slightly different

controller parameters are required for this mode.

VPS1 & VPS2 –

-99.9% to 999.9%

For position mode control, there are several ways to determine the valve

position values:

1) Position the valve to the closed or open positions (by use of the controller or

manually) and have the controller measure and record these positions. To

engage this mode, press the DSP button while either VPS1 or VPS2

parameters are called. %PW and DEV annunciators flash to indicate this

mode. The valve may then be positioned directly through the use of the

front panel UP and DOWN buttons. The UP button causes the valve to

move open and the DOWN button causes the valve to move closed.

Simultaneously, the controller indicates the slidewire position. After the

valve has been moved to the desired position (by use of the button and

observing the display), press PAR to record the position. This technique is

preferred because it compensates for leadwire resistance errors.

-37-

PCU12005 Datasheet(PDF) 45 Page - Red Lion Controls. Inc

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