Transmitter-Sensor Matching - Emerson Rosemount 644 Reference Manual

Reference Manual
00809-0200-4728
Perform a scaled output trim using a Field Communicator
Procedure
1. Connect an accurate reference meter to the transmitter at the CONNECT
2. From the HOME screen, enter the Fast Key sequence.
Perform a scaled output trim using AMS Device Manager
Procedure
1. Right click on the device and select Service Tools.
2. In the left navigation pane select Maintenance.
3. Find the Analog Calibration tab and select the Scaled Trim button.
4. Follow the screen prompts through the Analog Trimming process.
5.6

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, sensors with Callendar-Van Dusen constants are NIST-traceable.
The transmitter 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.
Figure 5-6: Standard vs. Actual Sensor Curve
*The Actual Curve is identified from the Callendar-Van Dusen equation.
Emerson.com/Rosemount
REFERENCE METER prompt by shunting the power to the transmitter through the
reference meter at some point in the loop.
Device Dashboard Fast Keys
Figure
Actual Curve
Standard IEC 751
"Ideal" Curve*
0 °C
Temperature, °C
3, 4, 5, 2
5-6.
Operation and Maintenance
March 2021
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