Emerson 375 User Manual page 50

3-10
Figure 3-3. Connecting Directly to a HART Device
HART compatible
Figure 3-4. Connecting with a 250 Ohm Resistor
HART compatible
Figure 3-3 illustrates how to connect the 375 Field
Communicator directly to the terminals of a HART
device.
device
+
-
+ -
Figure 3-4 illustrates how to connect the optional 250
ohm resistor. Attaching a resistor is necessary if less
than 250 ohms resistance is present in the HART loop.
device
–
+
To temporarily install the optional 250 ohm load resistor:
1. Insert the load resistor into the lead set jacks.
2. Open the loop to allow connection of the resistor in
series in the loop.
3. Close the loop using the lead set connectors.
HART Functionality
RL≥250Ω
-
+
mA
- +
Current
meter
+
Power
Supply
–
Optional
250-Ohm Load
Resistor
+
+
Power
supply
- -