D8 Series User’s Guide
Chapter 4: Operation and Setup
69
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. Changing the Set Point on page 66
• Put the controller in automatic mode. Changing the Control Mode and Output Power on page
For more information about the setup menus and parameters, Chapter 6: Menu and Parameter
Reference on page 95
Setting Up a Process Input
If you use a process input signal, you must set up scaling parameters 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 example, for a 0 to 20mA process input,
0mA is 0 percent, 10mA is 50 percent, and so on.
The conversion line scales the input signal to the engineering units of the process. For example, in
Figure 4.6 on the following page, a 20 percent input signal corresponds to 8 pounds per square inch
(PSI), and a 100 percent signal corresponds to 28 PSI.
