How to set up closed-loop control, Setting up a process input, Input scaling – Watlow Series D8 User Manual

Page 106: How to set up closed-loop control 88, Setting up a process input 88, Input scaling 88

Chapter 4: Operation and Setup

Series D8 User’s Guide

Watlow Anafaze

Doc. 0600-3120-2000

How to Set Up Closed-Loop Control

To set up closed-loop control:
•

Use the Input menu to specify the type of input signal

and, if necessary, how to scale that signal.

•

Use the Control menu to specify PID parameters and the

control hysteresis.

•

Use the Output menu to enable the heat and cool outputs

and to specify other output parameters.

•

Provide a set point:
•

To use cascade control to adjust the set point of the

loop, set up the Cascade menu.

•

To use ratio control, differential control, or remote

analog set point, set up the Ratio menu.

•

To manually adjust the set point of the loop, use the
Set point

parameter to enter the set point. See

•

For more information about the setup menus and parameters,

see the Menu and Parameter Reference chapter.

Setting Up a Process Input

If you use a process input signal, you must set up scaling pa-

rameters in the Input menu to scale the raw input signals to the

engineering units of the process.

Input Scaling

To scale the input, you enter values that represent two points

on a conversion line. Each point indicates an input signal level

and the corresponding process value.
The input signal is expressed as percent of full range. For ex-

ample, for a 0 to 20 mA process input, 0 mA is 0 percent, 10

mA is 50 percent, and so on.
The conversion line scales the input signal to the engineering

input signal corresponds to 8 pounds per square inch (PSI),

and a 100 percent signal corresponds to 28 PSI.