Wire mA1 in a HART multi-drop environmentFigure 3-10:
250 Ω
24 VDC
mA1+
HART
A
B
C
E
D
A. HART Device 1
B. HART Device 2
C. HART Device 3
D. Meter (mA+/HART output)
E. HART/Field Communicator
CAUTION!
• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable instrumentation cable to connect
the meter. The instrumentation cable should have individual screens, foil or braid over each twisted pair, and an
overall screen to cover all cores. Where permissible, connect the overall screen to earth at both ends (360° bonded
at both ends). Connect the inner individual screens at only the controller end.
• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable ports with metal
blanking plugs.
3.5.2 Wire external HART devices in an intrinsically safe area
You can wire up to three external HART devices in an intrinsically safe environment.
Following are diagrams showing a HART multidrop connection using a single barrier
connection (see Figure 3-11) and multiple barrier connections (see Figure 3-12).
Wiring
34 Micro Motion Compact Density Meter
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