Emerson 475 - Page 46

HART functionality
46
Wiring diagrams
Figure 3-3 shows how to connect the 475 Field Communicator to a
HART loop.
Figure 3-3. Connecting to a HART loop
HART device
Current
meter
RL≥250Ω
mA
Power supply
+
+
+
+
+
+
-
-
-
-
-
-
Figure 3-4 shows how to connect the 475 Field Communicator directly
to the terminals of a HART device.
Figure 3-4. Connecting directly to a HART device
Current
meter
mA
Power supply
RL≥250Ω
HART device
+
-
+
-
+
-+
-
+
-
+-
Figure 3-5 shows how to connect the optional 250 ohm resistor.
Attaching a resistor is necessary if less than 250 ohms resistance is
pre
sent in the HART loop.
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