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2.1.3
Control functionality
Control functionality is provided by five SPDT voltage-free contact relays in the control
unit (see
). The five relay outputs are fully field adjustable to perform a wide
variety of control, fault indication, or alarm duties.
For applications where the control unit functionality is linked to other external events,
there are two digital input ports for accepting contact closure signals.
The isolated 4–20 mA signal output from the control unit is driven by a Primary/Process
Value (PV) e.g. level.
Figure 2-2: Typical Application
F
A
B
C
G
20mA
4mA
E
E
D
D
A. Rosemount 3100 Series Transmitter
B. Rosemount 3490 Series Control Unit
C. 4–20 mA signal output
D. Relay
E. Pump
F. Bottom reference
G. 4–20 mA and HART signal
2.2
Control unit functions
2.2.1
Standard functions
The Rosemount 3490 Series Control Unit (“control unit”) provides these standard
functions:
Control unit overview
Reference Manual
January 2021
00809-0100-4841
10
Emerson.com/Rosemount
Summary of Contents for Rosemount 3490 Series
Page 4: ...4 ...
Page 8: ...Introduction Reference Manual January 2021 00809 0100 4841 8 Emerson com Rosemount ...
Page 16: ...Control unit overview Reference Manual January 2021 00809 0100 4841 16 Emerson com Rosemount ...
Page 36: ...Installation Reference Manual January 2021 00809 0100 4841 36 Emerson com Rosemount ...
Page 134: ...Getting started Reference Manual January 2021 00809 0100 4841 134 Emerson com Rosemount ...
Page 184: ...Additional features Reference Manual January 2021 00809 0100 4841 184 Emerson com Rosemount ...
Page 189: ...Reference Manual 00809 0100 4841 January 2021 Emerson com Rosemount 189 ...