The user is then notified that the loop may now be returned to automatic control. After the user presses OK the HART Communicator returns to the Calibration screen.
The HART Communicator is now at the starting screen for the Zero Temper Trim.
Full Temperature Trim
Starting at the Calibration screen, select the Full Level Trim procedure. This procedure trims the Temperature digital value measurement at two points. The first point trims the Temperature digital value measurement at the reference value of the RTD (1000 ohms). The second point is a Temperature value near the upper end of the desired Temperature range.
If the user selects Full Temper Trim from the Calibration screen, this screen will appear reminding the user that the loop should be removed from automatic control before proceeding. When this has been done, the user must press OK to continue.
This screen warns the user that proceeding will affect the sensor calibration. The user must press OK when ready to proceed.
The HART Communicator now requests that the temperature be set to the desired 0 deg C temperature point. If using a temperature simulator, adjust the simulator temperature to 0 deg C or if using a resistance box, adjust the resistance value to 1000 ohms. The user must press OK when the RTD or simulator is at the required value.
The transmitter will take about fifteen seconds to insure that the temperature signal has stabilized. Once the measurement is stable, the procedure will continue without user intervention. The HART communicator will then send the command to the transmitter to calculate the new Temperature zero calibration constant.
When the transmitter has completed its calculation it will reply to the HART Communicator. Then the HART Communicator will inform the user that the zero level point has been trimmed.
The HART Communicator now requests that the temperature be set to the desired temperature upper trim point. If using a temperature simulator, adjust the simulator temperature to the desired temperature or if using a resistance box, adjust it to the corresponding resistance value for this temperature. The user must press OK when the RTD or simulator is at the required value.
The transmitter will take about fifteen seconds to insure that the temperature signal has stabilized. Once the measurement is stable, the procedure will continue without user intervention.
The HART Communicator will now request the user to enter the value at the high trim point. The HART Communicator will display the last upper trim point, for example 100 deg C, and the user will enter the new upper trim point, for example 75 deg C. The HART Communicator will now send this value to the transmitter.
The HART communicator will then send the command to the transmitter to calculate the new Temperature gain calibration constant. When the transmitter has completed its calculation it will reply to the HART Communicator. Then the HART Communicator will inform the user that the sensor upper temperature trim point has been trimmed.
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