Watlow ez-zone pm - Filter Time Constant; Sensor Selection; Sensor Backup; Set Point Minimum and Maximum

Watlow EZ-ZONE
®
PMI Controller • 188 • Chapter 9 Features
Filter Time Constant
Filtering smooths an input signal by applying a rst-order lter time constant to the signal.
Filtering the displayed value makes it easier to monitor. Filtering the signal may improve the
performance of PID control in a noisy or very dynamic system.
Adjust the lter time interval with Filter Time fiL (Setup Page, Analog Input Menu). Exam-
ple: With a lter value of 0.5 seconds, if the process input value instantly changes from 0 to 100
and remained at 100, the display will indicate 100 after ve time constants of the lter value or
2.5 seconds.
Sensor Selection
You need to congure the controller to match the input device, which is normally a thermo-
couple, RTD or process transmitter.
Select the sensor type with Sensor Type SEn (Setup Page, Analog Input Menu).
Sensor Backup
Sensor backup maintains closed-loop control after an input failure by switching control to
input 2. The sensor backup feature is only available in an EZ-ZONE PM Integrated Limit or
Remote Set Point controller. Turn sensor backup on or off with Sensor Backup Enable S.ba
(Setup Page, Analog Input 1).
Note:
When Sensor Backup is enabled the Process Value function will automatically set itself to
Sensor Backup.
Set Point Minimum and Maximum
The controller has the ability to restrict the Set Points for the following modes of operation:
a. For closed loop control use Minimum Set Point and Maximum Set Point found in the Setup
Page, Loop Menu.
b. For Manual Power (open loop control) use Minimum Power and Maximum Power found in
the Setup Page, Loop Menu.
c. If a Limit is in use as part of an integrated control, set the Low Limit Set Point and High
Limit Set point between the settings Minimum Set Point and Maximum Set Point in the
Setup Page, Limit Menu.
Scale High and Scale Low
When an analog input is selected as process voltage or process current input, you must
choose the value of voltage or current to be the low and high ends. For example, when using
a 4 to 20 mA input, the scale low value would be 4.00 mA and the scale high value would be
20.00 mA. Commonly used scale ranges are: 0 to 20 mA, 4 to 20 mA, 0 to 5V, 1 to 5V and 0 to
10V.
Filtered Input Signal
Time
Temperature
Unfiltered Input Signal
Time
Temperature