Emerson Micro Motion SGM Series Configuration And Use Manual page 211

4.
Configuration and Use Manual
Figure C-6: Supply voltage and resistance requirements
A. External resistance (ohms)
B. Supply voltage VDC (volts)
C. Operating range
Note
To connect over a HART multidrop network:
a. Attach the leads from the signal converter to any point in the loop.
b. Add resistance as necessary to achieve at least one volt across the connection
points.
Important
HART/Bell 202 connections require a voltage drop of 1 VDC. To achieve this, add
resistance of 250–600 Ω to the connection.
Using ProLink III with the transmitter
203