3-19
On-line Operations
NOTE
To trim Sensor 2, repeat the same procedure, but in Step 1 disable
Sensor 1 instead of Sensor 2.
IMPORTANT
The Active Calibrator Mode
(1)
feature will automatically be enabled
when a sensor trim is performed and is automatically disabled when a
sensor trim is completed. If you choose to verify the trim after trim
completion, and you are using calibration equipment that requires
steady current, you may need to re-enable Active Calibrator Mode (see
“Sensor Current” on page 3-15). Disable Active Calibrator Mode when
verification is complete.
Transmitter-Sensor
Matching
The Model 3144 and 3244MV transmitters accept Callendar-Van Dusen
constants from a calibrated RTD schedule and generate a special
custom curve to match that specific sensor curve. Matching the specific
sensor curve with the transmitter significantly enhances the
temperature sensor measurement accuracy. See the comparison below.
The following input constants, included with specially-ordered
Rosemount temperature sensors, are required:
R
o
= Resistance at Ice Point
Alpha = Sensor Specific Constant
Beta = Sensor Specific Constant
Delta = Sensor Specific Constant
Refer to the Sensors Assemblies and Accessories Product Data Sheet
Volume 1, 2, and 3 to order Rosemount temperature sensors with
Callendar-Van Dusen constants.
To input Callendar-Van Dusen constants, perform the following
procedure:
1. From the Home screen, select
1 Device Setup, 4 Detailed Setup,
1 Sensors, 1 Process Sensor, 4 Sensor Setup, 1 Snsr 1 Config,
1 Snsr 1 Conn
. Select the appropriate sensor type and number of
wires at the prompt. This ensures that the sensor is not specified
as “Not Used.”
2. Select
OK
after you set the control loop to manual.
3. Select
4 Spec Snsr 1 Conn
to prepare to input constants.
4. Select the appropriate sensor configuration (2, 3, or 4 wire) at the
“Enter Special Sensor 1 Connection” prompt.
5. Select 1
alpha, delta, beta
at the “Select Coeff type” prompt. The
communicator prompts you to enter Ro, Alpha, Beta, and Delta
successively.
6. Enter the Ro, Alpha, Beta and Delta values from the stainless
steel tag attached to the specially-ordered sensor.
7. Select
OK
to accept the computed values for A, B, and C.
8. Select
OK
after you return the control loop to automatic control.
(1)
Previous transmitter versions use the RTD Current and T/C Pulsing Mode commands
instead of Active Calibrator Mode.
HART Fast Keys
1,4,1,1,3,1,4
