Emerson Rosemount 3490 Series Reference Manual page 62

Getting started
January 2021
Transmitter input channels on the Rosemount 3492
The Rosemount 3492 Control Unit supports the connection of two HART transmitters, but
not two 4–20 mA transmitters. The input channels and are referred to as Input Channel 1
and Input Channel 2.
For two HART transmitters, see:
• Programming Channel 1 for a HART input (advanced users)
• Programming Channel 2 for a HART input (Rosemount 3492 and advanced users only)
Sum, difference, or product calculations using input channels 1 and 2
Parameter P150 selects how final values from transmitter input channels 1 (D851) and 2
(D852) are processed together – sum, difference, or product calculation – before being
output to parameters D800, D801, D802, or D803 ('Answers').
The factory default programming (configuration) for P150 is to allow values from D851 to
go straight to D800.
4.4.6 Programming Input Channel 1 for a 4–20 mA input
(advanced users)
This section explains how to program (configure) the operation of the Input Channel 1 on
the control unit when a 4–20 mA transmitter is connected. Do not connect a second
transmitter.
The final result of the Input Channel 1 processing is stored in D800 and is referred to as the
control unit Primary / Process Value (PV). It is shown on the factory default configuration
of the display.
Procedure
1. Select displayed units for the control unit Primary/Process Value (PV).
2. Set Input Channel 1 to receive input from a 4–20 mA transmitter.
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First, it is essential to know the units for the measurements coming from the
transmitter. When this is known, navigate the menu system to SETUP →
[CONTROLLER] → DISPLAY → PV Units for the PV Units parameter P200 and then
select the measurement units that are to be shown for the control unit PV on the
display.
Note
Please note that the PV Units parameter (P200) does not automatically convert the
transmitter input or the control unit PV into alternative units. It is necessary to enter
a conversion factor into parameter P114.
a) Navigate to the menu SETUP → [CONTROLLER] → INPUT CHANNEL → Ch1
I/P Source for the Ch1 I/P Source parameter P111.
b) Select mA in 1 from the option list.
Reference Manual
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