Emerson Rosemount 3490 Series Reference Manual page 30

Installation
January 2021
3.4.6 Connecting HART transmitters to the Rosemount 3492
The Rosemount 3492 Control Unit takes the input from two HART transmitters and
calculates the sum, difference, or product of the two inputs.
Note
The transmitters must be HART compatible for the Rosemount 3492 to operate correctly.
Connection of the two transmitters to the Rosemount 3492 can be done by:
• Cabling both transmitter cables wired directly into Current Input terminals on the
Rosemount 3492
• Using a single cable wired directly into Current Input terminals with the two
transmitters connected to this single cable via a suitable junction box
Figure 3-9: Connecting Two HART transmitters
1
2
3
A. HART transmitter Tx1
B. HART transmitter Tx2
C. Junction box
Connect the two HART transmitters
For correct operation, each HART transmitter must be changed to "multi-drop" mode to
allow them to communicate with the Rosemount 3492 Control Unit through a common
connection. Each HART transmitter must therefore have their poll address changed from
the factory default address of "0" to a unique address.
The Rosemount 3492 Control Unit is used to achieve this address change, but requires the
transmitters to be connected in a specific sequence as detailed here:
Procedure
1.
2. Check the voltage-selector-switch is set for the correct voltage on the mains-
30
(Figure 3-9), or
A
B
With the power supply turned off, connect the first HART transmitter to the
Current Input terminals on the control unit.
powered control unit (115 or 230 Vac), and then turn the power on.
C
1
2
3
Reference Manual
00809-0100-4841
(Figure 3-9).
A
B
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