Watlow PM LEGACY PM3 - Page 87

Watlow PM LEGACY™ Limit Controller • 87 • Chapter 8 Features
Note: The user may only calibrate one sensor type. If the calibrator interferes with open thermo-
couple detection, set Sensor Type sEn in Setup Page sEt, Analog Input Menu ai to millivolt ЛЏu
instead of Thermocouple tC to avoid interference between the calibrator and open thermocouple
detect circuit for the duration of the calibration process. Be sure to set sensor type back to the
thermocouple type utilized.
Note: The Electrical Measurement value will be in the units that are selected. i.e. - Millivolts,
volts, milliamps, or ohms.
1. Disconnect the sensor from the controller.
2. Record the Calibration Offset i.Ca parameter value in the Operations Page opEr, Analog Input
Menu ai then set value to zero.
3. Wire the precision source to the appropriate controller input terminals to be calibrated. Do not
have any other wires connected to the input terminals. Please refer to the Install and Wiring sec-
tion of this manual for the appropriate connections.
4. Ensure the controller sensor type is programmed to the appropriate Sensor Type sEn to be utilized
in the Setup Page sEt, Analog Input Menu ai.
5. Enter Factory Page fCty, Calibration Menu Ca L via front panel or PM LEGACY™ Limit
Configurator Software.
6. Select the Calibration CaL input instance to be calibrated. This corresponds to the analog input to
be calibrated.
7. Set Electrical Input Slope ELi.s to 1.000 and Electrical Input Offset ELi.o to 0.000 (this will cancel
any prior user calibration values)
8. Input a Precision Source Low value. Read Electrical Measurement value ЛЏu of controller via PM
LEGACY™ Limit Configurator or RUI. This will be referred to as Electrical Measured Low. Record
low value ______________.
9. Input a Precision Source High value.
10. Read Electrical Measurement value ЛЏu of controller via PM LEGACY™ Limit Configurator
or RUI. This will be referred to as Electrical Measured High. Record high value ________.
11. Calculated Electrical Input Slope = (Precision High – Precision Low) / (Electrical Measured
High - Electrical Measured Low) Calculated Slope value ___________
12. Calculated Electrical Input Offset = Precision Low - (Electrical Input Slope * Measured
Low) Calculated Offset value ___________.
13. Enter the calculated Electrical Input Slope ELi.s and Electrical Input Offset ELi.o into
the controller.
14. Exit calibration menu.
15. Validate calibration process by utilizing a calibrator to the analog input.
16. Enter calibration offset as recorded in step 2 if required to compensate for sensor error.
Setting Electrical Input Slope ELi.s to 1.000 and Electrical Input Offset ELI.o to 0.000, restores facto-
ry calibration as shipped from factory.