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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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