Model 275 HART Communicator Note The Instrument Mode must be Out Of Service and the Protection set to None or Configuration before it can be calibrated.
Analog Input Calibration To calibrate the analog input sensor, connect a variable current source to the instrument terminals labeled LOOP+ and LOOP–. The current source should be capable of generating an output of 4 to 20 milliamps. Select Analog In from the Calibrate menu, then follow the prompts on the HART Communicator display to calibrate the analog input sensor. 1. Set the current source to the target value shown on the display. The target value is the Input Range Low value. Press OK. 2. The following message appears:
Use Increase and Decrease selections until the displayed current matches the target. Press OK when you have read this message. 3. The value of the Analog Input appears on the display. Press OK to display the adjustment menu. 4. From the adjustment menu, select the direction and size of adjustment to the displayed value. Selecting large, medium, and small adjustments causes changes of approximately 0.4 mA, 0.04 mA, and 0.004 ma, respectively. If the displayed value does not match the current source, press OK, then repeat this step (step 4) to further adjust the displayed value. When the displayed value matches the current source, select Done and go to step 5. 5. Set the current source to the target value shown on the display. The target value is the Input Range High value. Press OK. 6. The following message appears:
Use Increase and Decrease selections until the displayed current matches the target. Press OK when you have read this message. 7. The value of the Analog Input appears on the display. Press OK to display the adjustment menu.
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8. From the adjustment menu, select the direction and size of adjustment to the displayed value. Selecting large, medium, and small adjustments causes changes of approximately 0.4 mA, 0.04 mA, and 0.004 ma, respectively. If the displayed value does not match the current source, press OK, then repeat this step (step 8) to further adjust the displayed value. When the displayed value matches the current source, select Done and go to step 9. 9. Place the instrument In Service and verify that the analog input displayed matches the current source.
Auto Calibrate Travel User interaction is only required with Auto Calibrate Travel when the valve is sliding-stem. Rotary valves require no user interaction. If the valve is sliding-stem, you may interact in order to more accurately set the crossover. Select Auto Calib Travel from the Calibrate menu, then follow the prompts on the HART Communicator display to automatically calibrate travel. 1. Select the method of crossover adjustment: manual, last value, or default. If you select Last Value, the crossover setting currently stored in the instrument is used and there are no further user interactions with the auto-calibration routine (go to step 4). If you select Default, an approximate value for the crossover is written to the instrument and there are no further user interactions with the auto-calibration routine (go to step 4). If you select Manual, you are asked to select an adjustment source, either analog or digital. If you use a current source to adjust the crossover, select Analog and go to step 2. If you wish to adjust the current source digitally, select Digital and go to step 3. 2. If you selected Analog as the crossover adjustment source, the HART Communicator prompts you to adjust the current source until the feedback arm is 90° to the actuator stem, as shown in figure 10. After you have made the adjustment, press OK and go to step 4. 3. If you selected Digital as the crossover adjustment source, the HART Communicator displays a menu to allow you to adjust the crossover. Select the direction and size of change required to set the feedback arm so it is 90° to the actuator stem, as shown in figure 10. Selecting large, medium, and small adjustments to the crossover causes changes of approximately 10.0°, 1.0°, and 0.1°, respectively, to the rotation of the crossover arm. If another adjustment is required, repeat step 3. Otherwise, select Done and go to step 4. 4. The remainder of the auto-calibration procedure is automatic. It is completed when the messages and prompts to place the instrument In Service appear.