Transmitter-Sensor Matching - Emerson Rosemount 248 Reference Manual

Reference Manual
00809-0100-4825
8. Select OK when the temperature stabilizes. The communicator displays the output
9. Enter the lower or upper trim point, depending on the selection in Step 6.
Output trim or scaled output trim
Perform an output trim or a scaled output trim if the digital value for the primary variable
matches the plant's standards, but the transmitter's analog output does not match the
reading on the output device. The output trim function calibrates the transmitter to a 4–
20 mA reference scale; the scaled output trim function calibrates to a user-selectable
reference scale. To determine the need for an output trim or a scaled output trim, perform
a loop test as shown on
Figure 4-1: Dynamics of Smart Temperature Measurement
4.3

Transmitter-sensor matching

Use Transmitter-Sensor Matching to enhance the temperature measurement accuracy of
the system and if you have a sensor with Callendar-Van Dusen constants. When ordered
from Emerson Process Management, sensors with Callendar-Van Dusen constants are
NIST-traceable.
The Rosemount 248 accepts Callendar-Van Dusen constants from a calibrated RTD
schedule and generates a special custom curve to match that specific sensor Resistance
vs. Temperature performance.
Rosemount 248 Temperature Transmitter Reference Manual
stabilize. Use a bath, furnace or isothermal block, measured with a site-standard
thermometer, as the known temperature source.
value the transmitter associates with the input value provided by the calibration
device.
Diagnostics and service.
Figure 4-2.
Operation and Maintenance
May 2019
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