Watlow CPC400 Bedienungsanleitung PDF herunterladen (Seite 72)

Chapter 3: Operation and Setup CPC400 Series User’s Guide

58 Watlow Anafaze Doc. 0600-2900-2000

the PID parameters to determine when control switches be-

tween heating and cooling.

How to Set Up Closed-Loop Control

The following are the basic steps to set up closed-loop con-

trol for a typical control loop:

1. Use the Input menu to specify the type of input signal

and, if necessary, how to scale that signal.

2. If using on/off or both heat and cool outputs, use the

Control menu to specify the control hysteresis.

3. Use the Output menu to enable the heat and/or cool

outputs and to specify the control output signal form.

4. Enter a set point. See Changing the Set Point on page

54.

5. Put the channel in Tune mode. See Changing the Con-

trol Mode and Output Power on page 55.

For more information about the setup menus and parame-

ters, see Chapter 5, Menu and Parameter Reference.

Setting Up a Process or Pulse Input

If you use a process or pulse input signal, you must set up

scaling parameters in the Input menu to scale the raw in-

put 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.

For a pulse input, the input signal range is 0 to 2000 Hz.

For a process input, the input signal is expressed as per-

cent of full range. For example, for a 0 to 20 mA process in-

put, 0 mA is 0 percent, 10 mA is 50 percent, and so on.

The conversion line scales the input signal to the engineer-

ing units of the process. For example, in Figure 3.6, a 20

percent input signal corresponds to 8 pounds per square

inch (PSI), and a 100 percent signal corresponds to 28 PSI.

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Watlow CPC400 Bedienungsanleitung Seite 72