Emerson Rosemount 644 Reference Manual page 50

Configuration
March 2021
Figure 2-25: Typical Multi-dropped Network
A
H
A. Power supply
B. Power supply impedance
C. 250 Ω
D. Field Communicator
E. Computer or DCS
F. HART interface
G. 4–20 mA
H. Transmitter
Note
Rosemount 644 Transmitters are set to address 0 at the factory, allowing them to operate
in the standard point-to-point manner with a 4–20 mA output signal. To activate
multidrop communication, the transmitter address must be changed to a number
between 1 and 15. This change deactivates the 4–20 mA analog output, sending it to 4
mA. The failure mode current also is disabled.
2.12.1 Changing a transmitter address
To activate multi drop communication, the transmitter poll address must be assigned a
number from 1–15 for HART Revision 5, and 1–63 for HART Revision 7. Each transmitter in
a multi dropped loop must have a unique poll address.
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B C
F
G
D
E
Reference Manual
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