5 Service and maintenance
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB | 63
Calibrating the process temperature sensor
The process temperature input can be calibrated to match the user’s reference over a range of -80 °F to +1500 °F. To calibrate
the input use the following steps.
IMPORTANT NOTE: If using a RTD simulator or digital RTD calibrator, remove the RTD from the transmitter
and wire the connections according to the calibrator documentation.
1. Use the key pad to locate and select Calibrate > Process Temp. Sensor > Low Trimming.
2. Set the input to the lowest thermal point expected from the application:
a. Allow the display to stabilize, showing the current measured value. When stabilized, continue.
b. Enter the low value in the New field.
i. To enter a value, use the up or down arrow to locate the value of the first digit. When selected, press the left soft
key for Next. This moves the cursor to the next digit.
ii. Repeat this process for each digit until the entire low value is selected. To change a digit’s value after moving
past it, select the Next key until the cursor reaches the incorrect digit then change it.
c. When the value is equal to the value of the calibrator, then select Continue. The user should now see the indication
that the low trim calibration is complete.
3. Select High Trimming from the menu.
a. Set the input to the highest thermal point expected from the application.
b. The display will have the current measured value. Select Continue when the reading is stable.
c. Enter the high value in the New field.
i. To enter a value, use the up or down arrow to locate the value of the first digit. When selected, press the left soft
key for Next. This moves the cursor to the next digit.
ii. Repeat this process for each digit until the entire high value is selected. To change a digit’s value after moving
past it, select the Next key until the cursor reaches the incorrect digit then change it.
d. When the value is equal to the value of the calibrator, then select Continue. The user should now see the indication
that the low trim calibration is complete.
4. Select Save to User.
a. Select OK.
b. The bar graph will show the status of the save.
5. Select Exit to return to the main screen.
6. Remove the RTD simulator or calibrator and re-attach the RTD wiring.
7. When the DP, SP, and process temperature sensors have been calibrated, follow the procedure in section 4.3.4, Putting
the transmitter in service, to return the transmitter to operation.
The process temperature sensor is now calibrated.
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