MT100 Multipoint Flow Meter INSTALLATION
I/O Connections
As shown in Figure 23 the SB4 main board provides an input/output signal interface for connection to various peripheral interfaces. For
these interfaces, route the cable/wires through a conduit opening at the enclosure bottom and connect to the appropriate
connector/terminals.
HART
Connect the installation HART wiring to the appropriate J9 Phoenix connector terminals depending on the application. The connector
accepts 28-16 AWG (0.14 mm
2
-1.5 mm
2
) wire (refer to Table 2, page 23 for wire size vs. length info).
● Single Connection – The instrument supplies power to the loop and controls the current as well. For this application connect HART+
to J9-1 (INT+) and HART- to J9-2 (INT-).
● Network (Multidrop) Connection – The instrument receives loop power from the network, and controls the current. For this
application connect external HART+ to J9-2 (EXT+) and external HART- to J9-4 (RTN).
The block diagram in Figure 24 below shows the single connection and multidrop HART setups. Use a 250 Ω 1%, ≥ 0.3 W resistor as shown in the
diagram below only if the external HART interface/wiring does not have this resistance built-in (HART requires a minimum loop resistance of 230 Ω).
C
ABLING RECOMMENDATION
Use a shielded, twisted-pair instrument grade wire (min. 24 AWG for runs less than 5000 ft/1500 m; min. 20 AWG for longer distances). The RC
value of the wire (Total Resistance x Total Capacitance) must be less than 65 µs (not a concern for point-to-point topology with a run less than
328 ft/100 m). A cable designed for HART/RS-485 such as Belden 3105A is recommended for complex setups and/or particularly long runs.
The HART communications digital signals are superimposed on top of the channel #1 current loop (4-20 mA) output.
When HART communications is in use, the HART current loop channel #1 MUST be configured as FLOW to comply
with the HART protocol. The channel #1 current loop output is configured as FLOW by default at the factory.
MT100
HART
J9-1
J9-2
Internal Loop Power External Loop Power
HART
I/O
HART
HART– HART+
+
I/O
HART
Master
R
LOAD
J9-1
NC
MT100
–
HART
Master
R
LOAD
Network P.S.
24 VDC
HART
+
J9-2
–
J9-4
(a) HART Single Connection
MT100
HART
J9-1
J9-4
J9-2
MT100
HART
J9-1
J9-4
J9-2
MT100
HART
J9-1
J9-4
J9-2
MT100
HART
Network P.S.
24 VDC
HART
Master
J9-1
R
LOAD
HART
I/O
J9-4
J9-2
HART+ HART–
(b) HART Network, Multidrop
C01364-1-1
Figure 24 – Single Connection and Multidrop HART Setups
Fluid Components International LLC 27
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