Watlow EZ-ZONE RM Limit Module Rev C - Manual (Page 83)

Watlow EZ-ZONE ® RML Module • 80 • Chapter 6 Features
5. Check the Electrical Measurement to see whether
it now matches the signal. If it doesn’t match, ad-
just Electrical Offset again.
6. Apply the high source signal to the input. Mea-
sure the signal to ensure it is accurate.
7. Read the value of Electrical Measurement for
that input.
8. Calculate the gain value by dividing the low
source signal by this value.
9. Set Electrical Slope [ELi;S] (Factory Page, Cali-
bration Menu) for this input to the calculated
gain value.
10. Check the Electrical Measurement to see wheth-
er it now matches the signal. If it doesn’t match,
adjust Electrical Slope again.
Set Electrical Offset to 0 and Electrical Slope to 1 to
restore factory calibration.
Follow these steps for an RTD input:
1. Measure the low source resistance to ensure it
is accurate. Connect the low source resistance to
the input you are calibrating.
2. Read the value of Electrical Measurement [`Mu]
(Factory Page, Calibration Menu) for that input.
3. Calculate the offset value by subtracting this val-
ue from the low source resistance.
4. Set Electrical Input Offset [ELi;o] (Factory Page,
Calibration Menu) for this input to the offset val-
ue.
5. Check the Electrical Measurement to see whether
it now matches the resistance. If it doesn’t match,
adjust Electrical Offset again.
6. Measure the high source resistance to ensure it
is accurate. Connect the high source resistance to
the input.
7. Read the value of Electrical Measurement for
that input.
8. Calculate the gain value by dividing the low
source signal by this value.
9. Set Electrical Slope [ELi;S] (Factory Page, Cali-
bration Menu) for this input to the calculated
gain value.
10. Check the Electrical Measurement to see wheth-
er it now matches the signal. If it doesn’t match,
adjust Electrical Slope again.
Set Electrical Offset to 0 and Electrical Slope to 1 to
restore factory calibration.
Filter Time Constant
Filtering smoothes an input signal by applying a
first-order filter time constant to the signal. Filter-
ing 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 filter time interval with Filter Time
[`FiL]
(Setup Page, Analog Input Menu). Example:
With a filter 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 five time con-
stants of the filter value or 2.5 seconds.
Filter Time Constant
Unfiltered Input Signal
Time
Temperature
Filtered Input Signal
Time
Temperature
Sensor Selection
You need to configure the controller to match the in-
put device, which is normally a thermocouple, RTD or
process transmitter.
Select the sensor type with Sensor Type [`Sen]
(Setup Page, Analog Input Menu).
Set Point Low Limit and High Limit
The controller constrains the set point to a value be-
tween a set point low limit and a set point high limit.
Set the set point limits with Low Set Point [`L;SP]
and High Set Point [`h;SP] (Setup Page, Loop Menu).
There are two sets of set point low and high lim-
its: one for a closed-loop set point, another for an
open-loop set point.
Set Point Range (must be between Range High and Range Low)
Low Limit of selected functional range
High Limit of selected functional range
Gas Pressure
Range Low and Range High
Range High Range (between High Limit of Sensor and Range Low)
Range Low Range (between Low Limit of Sensor and Range High)
Set Point Low
Set Point High
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.
You can create a scale range representing other
units for special applications. You can reverse scales
from high values to low values for analog input sig-
nals that have a reversed action. For example, if 50
psi causes a 4 mA signal and 10 psi causes a 20 mA
signal.