Rosemount™ 3490 Series
4-20 mA + HART® Compatible Controller
Reference Manual
00809-0100-4841, Rev CB
January 2022
Safety messages
NOTICE
Read this manual before working with the product. For personal and system safety, and for optimum product performance,
ensure you thoroughly understand the contents before installing, using, or maintaining this product.
For technical assistance, contacts are listed below:
Customer Central
Technical support, quoting, and order-related questions.
• United States - 1-800-999-9307 (7:00 am to 7:00 pm CST)
• Asia Pacific- 65 777 8211
North American Response Center
Equipment service needs.
• 1-800-654-7768 (24 hours a day — includes Canada)
• Outside of these areas, contact your local Emerson representative.
WARNING
Replacement equipment or spare parts not approved by Emerson for use as spare parts could reduce the capabilities of the
Rosemount 3490 Series Control Unit, and may render the instrument dangerous.
Use spare parts supplied or sold by Emerson.
WARNING
Failure to follow these installation guidelines could result in death or serious injury.
The Rosemount 3490 Series Control Unit must be installed, connected, commissioned, operated, and maintained by suitably
qualified personnel only, observing any national and local requirements that may apply.
Use the equipment only as specified in this manual. Failure to do so may impair the protection provided by the equipment.
Explosions could result in death or serious injury.
Please review the approvals section of this reference manual for any restrictions associated with an installation.
Electrical shock could cause death or serious injury.
If the control unit is installed in a high voltage environment and a fault condition or installation error occurs, high voltage may be
present on leads and terminals.
Use extreme caution when making contact with the leads and terminals.
Make sure that power to the control unit is off while making connections.
WARNING
Physical access
Unauthorized personnel may potentially cause significant damage to and/or misconfiguration of end users’ equipment. This could
be intentional or unintentional and needs to be protected against.
Physical security is an important part of any security program and fundamental to protecting your system. Restrict physical access
by unauthorized personnel to protect end users’ assets. This is true for all systems used within the facility.
2
CAUTION
The products described in this document are NOT designed for nuclear-qualified applications. Using non-nuclear qualified
products in applications that require nuclear-qualified hardware or products may cause inaccurate readings. For information on
Rosemount nuclear-qualified products, contact your local Emerson Sales Representative.
3
4
Reference Manual Contents
00809-0100-4841 January 2022
Contents
Chapter 1 Introduction.............................................................................................................. 7
1.1 Using this manual........................................................................................................................ 7
1.2 Control unit versions and software releases................................................................................. 7
1.3 Product recycling/disposal...........................................................................................................7
Chapter 2 Control unit overview................................................................................................ 9
2.1 About the Rosemount™ 3490 Series Control Unit.........................................................................9
Control unit functions................................................................................................................10
2.2
2.3 Control unit front panel............................................................................................................. 12
Chapter 3 Installation...............................................................................................................17
3.1 Safety messages........................................................................................................................ 17
3.2 Considerations before installation............................................................................................. 17
3.3 Mounting the control unit..........................................................................................................21
3.4 Electrical installation..................................................................................................................23
Chapter 4 Getting started.........................................................................................................37
4.1 First time power-up................................................................................................................... 37
4.2 Main menu................................................................................................................................ 41
4.3 Programming using the front panel........................................................................................... 44
4.4 Programming of the control unit............................................................................................... 51
Chapter 5 Service and troubleshooting.................................................................................. 135
5.1 Safety messages...................................................................................................................... 135
5.2 Servicing the control unit.........................................................................................................135
5.3 Health checking the control unit..............................................................................................139
5.4 Service support........................................................................................................................145
Appendix A Specifications and reference data........................................................................... 147
A.1 General....................................................................................................................................147
A.2 Display.................................................................................................................................... 147
A.3 Electrical..................................................................................................................................147
A.4 Mechanical.............................................................................................................................. 150
A.5 Environment............................................................................................................................151
A.6 Dimensional drawings............................................................................................................. 153
A.7 Rosemount 3491, 3492, and 3492 ordering information.........................................................156
A.8 Accessory................................................................................................................................ 157
Appendix B Product certifications............................................................................................. 159
B.1 European directive information............................................................................................... 159
B.2 Installing equipment in North America.................................................................................... 159
B.3 North America......................................................................................................................... 159
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B.4 Europe.....................................................................................................................................160
B.5 International............................................................................................................................160
B.6 Republic of Korea.....................................................................................................................161
B.7 ATEX and IECEx conditions for safe use (I1 and I7)....................................................................161
B.8 System control drawing...........................................................................................................164
Appendix C Menus and parameter............................................................................................ 165
Appendix D Additional features................................................................................................ 181
D.1 Restoring the factory defaults................................................................................................. 181
D.2 Advanced parameter access....................................................................................................181
Appendix E Support for HART® Transmitters............................................................................ 185
E.1
Overview..................................................................................................................................185
E.2 Fully supported HART transmitters.......................................................................................... 185
E.3 Generic support for HART transmitters.................................................................................... 185
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Reference Manual Introduction
00809-0100-4841 January 2022
1 Introduction
1.1 Using this manual
This manual provides installation, configuration and maintenance information for the
Rosemount™ 3490 Series Control Unit (“control unit”).
Control unit overview contains an overview of the wall- and panel-mounting versions,
transmitter inputs, control functions, and front panel features.
Installation contains mechanical and electrical installation instructions.
Getting started contains instructions for powering on the control units the first time with a
new HART® transmitter connected, followed by a quick tour of the menu system and
instructions for configuring the control unit using the front panel.
Service and troubleshooting contains instructions for replacing the fuse and a guide to the
health check system, which includes tests, calibrations, live readings, and diagnostic data
for the control unit.
Specifications and reference data contains specification data and ordering information.
Product certifications contains European directive information, hazardous locations
certifications and approval drawings.
Menus and parameter contains full menu maps for the control unit and generic HART
transmitters.
Additional features contains instructions for restoring the factory default settings and for
using the advanced menu for accessing parameter screens quickly.
Support for HART® Transmitters contains an overview of fully supported Rosemount 3100
Series Transmitters and generic support using Universal and Common Practice
Commands.
1.2 Control unit versions and software releases
The following control unit versions are covered in this product manual:
• Rosemount 3491 Standard Control Unit
• Rosemount 3492 Differential Control Unit
• Rosemount 3493 Logging Control Unit
The software release covered in this product manual is issue 4.00.00 (and above).
1.3 Product recycling/disposal
Recycling of equipment and packaging should be taken into consideration and disposed of
in accordance with local and national legislation or regulations.
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8 Emerson.com/Rosemount
Reference Manual Control unit overview
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2 Control unit overview
2.1 About the Rosemount™ 3490 Series Control Unit
2.1.1 Wall and panel mounting options
The wall mounting option has a tough, weatherproof enclosure for internal or external
installation. There are two styles: IP-rated wall mount and NEMA® 4X-rated wall mount.
The panel mounting option has a black enclosure, and is designed for control room panel
or cabinet installation.
Figure 2-1: Mounting Options
A. Wall mount, IP65 version
B. Wall mount, NEMA® 4X version
C.
Panel mount version
2.1.2 4-20 mA HART® transmitter input options
4–20 mA HART transmitter input options:
• The Rosemount 3491 Standard Control Unit and the Rosemount 3493 Logging Control
Unit accepts one 4–20mA or HART transmitter input.
• The Rosemount 3492 Differential Control Unit accepts two HART transmitter inputs.
Note
The Rosemount 3490 Series is designed for non hazardous (safe) area installation, but can
be connected to a transmitter installed in a hazardous area.
Related information
Product certifications
Emerson.com/Rosemount 9
F
A
B
C
G
20mA
4mA
E E
D
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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 Figure 2-2). 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
A. Rosemount 3100 Series Transmitter
B. Rosemount 3490 Series Control Unit
4–20 mA signal output
C.
D. Relay
E. Pump
F. Bottom reference
G. 4–20 mA and HART signal
2.2 Control unit functions
2.2.1 Standard functions
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The Rosemount 3490 Series Control Unit (“control unit”) provides these standard
functions:
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Calculation and display of the control unit PV
The control unit PV is typically a live transmitter reading, which can be any measured value
e.g. level, temperature, or Pressure.
Alternatively, the control unit PV is a volume or flow value calculated using the live
transmitter level reading. The control unit is pre-programmed with standard tank shapes
and flow algorithms to simplify the configuration for calculating volume or flow from the
live transmitter level reading. A 20-point programmable look-up table is provided for nonstandard applications.
Output of measured variable as an isolated 4–20 mA signal
The output signal is driven by the control unit PV.
Relay control functions
There are five freely assignable relay outputs. By default, Relay 5 is a fault relay but can be
assigned to a control duty. The other relays are available to operate at user-entered PV
values.
The control unit is pre-programmed with popular pump control routines for wet well and
sump control, along with energy saving overrides.
Voltage-free (digital) contact closure inputs
There are two digital input ports for accepting contact closure signals to override control
unit functions.
HART transmitter interrogation and programming
Any HART transmitter can be connected. The control unit recognizes the transmitter as an
“unknown instrument” but supports the Universal and Common Practice HART
commands.
When a Rosemount 3100 Series Transmitter is connected, the control unit recognizes the
transmitter and allows full access to the transmitter’s configuration parameters. Refer to
the Rosemount 3101/3102/3105 Reference Manual or Rosemount 3107/3108 Reference
Manual for full information about programming the transmitter parameters (e.g.
transmitter bottom reference) using the control unit and other HART-based devices.
Related information
Support for HART Transmitters
2.2.2 Difference, sum, and product functions
The Rosemount 3492 Differential Control Unit has all the functions of the standard control
unit, plus extra functions for calculating the difference, sum, or product of two separate
inputs from HART transmitters.
2.2.3 Data logging functions
The Rosemount 3493 Logging control unit has all the functions of the standard control
unit, plus a 7000 event logging function.
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C
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2.3 Control unit front panel
This front panel fascia has an integral keypad, display, and health status LED.
Figure 2-3: Front Panel Fascia
A. 4-line back-lit LCD display
B. Keypad
C.
Status LED
2.3.1 Keypad
The membrane keypad has six function buttons (Table 2-1). The buttons are used for
navigating a menu system and for viewing or changing application parameters.
Table 2-1: Keypad Function Buttons
Button What the button will do
When the PV is shown, use the red (enter) button to access the menu system. At
other times, this button is for selecting a menu option and for confirming
something.
When navigating the menu system, the up arrow button is for moving upwards
one line. At other times, this button is for scrolling through a list of alphanumeric
characters or a list of options.
When navigating the menu system, the down arrow button is for moving
downwards one line. At other times, this button is for scrolling through a list of
alphanumeric characters or a list of options.
The left arrow button is for moving left e.g. to another character when editing a
parameter value.
12 Emerson.com/Rosemount
The right arrow button is for moving right e.g. to another character when editing
a parameter value.
When navigating the menu system, use the escape button to return to a previous
menu level and the Full PV display. At other times, e.g. while editing, the button is
for restoring a setting that is being edited.
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2.3.2 Status LED
The LED is positioned just below the LCD display. It flashes once per second to indicate
that the control unit and transmitters are operating correctly. The LED is constantly lit if
there are operating difficulties e.g. a transmitter fault.
Related information
Control unit front panel
2.3.3 Display
After the power-up and self-checks are completed, the Full PV display is presented. The
default Full PV display typically features a digital clock, a measured variable with display
units, and status icons. There are some display differences between control units:
• On the Rosemount 3491 and 3492, a bar graph indicates the 4–20 mA output signal.
The Rosemount 3493 display can be changed to show the bar graph.
• On the Rosemount 3492, an extra icon on the first line and indicates if one or two HART
transmitters connected to the control unit.
• On the Rosemount 3493, there are two totalizers displayed; one above and one below
the control unit PV.
Emerson.com/Rosemount 13
B C
DE
A
F
J
G H
K
I
Rosemount 3491
Rosemount 3492
Rosemount 3493
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Figure 2-4: Typical Control Unit Displays
A. Program/Run App mode (locked padlock = Run App)
B. HART transmitter communicating (absent if Idle)
Relay (RL) status: O = De-energized, ‣ = Energized, A = Alarm, S = Sampler, T = Totalizer
C.
D. PV of control unit
E. Bar graph of 4–20 mA output
F. Digital input status: O = Open, ‣ = Closed
G. HART transmitter allocated: Left vertical bar = Tx1; Right vertical bar = Tx2
H. HART transmitter communicating (1=Tx1, 2=Tx2)
I. Relay (RL) status: O= De-energized, ‣ = Energized, A = Alarm, S = Sampler, T = Totalizer
J. Totalizer 1
K. Totalizer 2 (daily total)
Restore the full PV display
After a period of keypad inactivity, the display automatically changes to the Large PV
Display. This shows only the control unit PV and display units, but in a larger character size
to facilitate easier viewing.
Procedure
To restore the Full PV Display, press the red (enter) button.
Note
The Large PV Display feature can be switched off using parameter P574.
14 Emerson.com/Rosemount
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1.572 m
12:47
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Figure 2-5: Display Views
A. Large PV Display
B. Full PV Display
Related information
Display configuration options
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3 Installation
3.1 Safety messages
Procedures and instructions in this manual may require special precautions to ensure the
safety of the personnel performing the operations. Information that raises potential safety
issues is indicated by a caution symbol ( ). The external hot surface symbol ( ) is used
when a surface is hot and care must be taken to avoid possible burns. If there is a risk of an
electrical shock the (
beginning of each section before performing an operation preceded by this symbol.
WARNING
Failure to follow these installation guidelines could result in death or serious injury.
The Rosemount™ 3490 Series Control Unit (“control unit”) must be installed, connected,
commissioned, operated, and maintained by suitably qualified personnel only, observing
any national and local requirements that may apply.
) symbol is used. Refer to the safety messages listed at the
Use the control unit only as specified in this manual. Failure to do so may impair the
protection provided by the equipment.
Explosions could result in death or serious injury.
Please review the approvals section of this reference manual for any restrictions associated
with an installation.
Electrical shock could cause death or serious injury.
If the control unit is installed in a high voltage environment and a fault condition or
installation error occurs, high voltage may be present on leads and terminals.
Use extreme caution when making contact with the leads and terminals.
Make sure that power to the control unit is off while making connections.
3.2 Considerations before installation
3.2.1 Safety considerations
Note
The Rosemount 3490 Series is designed for non-hazardous (safe) area installation, but
can power and take input from an intrinsically safe transmitter installed in a hazardous
area.
Guidelines
1. This product is classified type A in accordance with European EMC directive
2014/30/EU. To ensure electro-magnetic compatibility, in any member country,
this product should not be installed in a residential area.
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2. Do not mount the control unit on a structure that is subject to vibration, or in a
position where damage may be caused by impact, thermal stress or liquid ingress.
3. The fuse must only be replaced with the type specified.
4.
If the equipment is likely to come into contact with aggressive substances, it is the
responsibility of the user to take suitable precautions that prevent it from being
adversely affected, thus ensuring that the type of protection is not compromised.
Aggressive Substances - e.g. acidic liquids or gases that may attack metals or
solvents that may affect polymeric materials.
Suitable Precautions - e.g. regular checks as part of routine inspections or
establishing from the material's data sheet that it is resistant to specific chemicals.
5. The user should not repair this equipment.
6. Terminal 30 (intrinsically safe earth/ground) of the panel mount control unit must
be connected to a high integrity earth/ground point.
For a wall mount control unit, it is recommended that Terminal 30 is connected to a
high integrity earth/ground point.
7. A mains-powered control unit must not be connected to a supply exceeding 250 V
r.m.s. or dc, or to apparatus containing a source of voltage exceeding 250 V r.m.s.
or dc.
8. A direct current (dc) powered control unit must not be connected to a supply
exceeding 30 Vdc or apparatus containing a source of voltage exceeding 30 Vdc.
9. The intrinsically safe outputs of the control unit may be connected to certified
equipment used in a hazardous area.
10. Cable between the control unit and transmitter should be shielded, twisted-pair
with the shield connected to terminal 3 (marked with earth symbol) on the control
unit. The shield should be left unconnected at the transmitter unless there is a
terminal specifically provided for this purpose.
11. Cable runs should be separate from any high voltage or mains cables to avoid
crosstalk or interference.
Related information
Product certifications
Specifications and reference data
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3.2.2 Installation guidelines for the panel mount version
Figure 3-1: Panel Mount
• This housing is rated IP40 and is designed for panel mounting in a weatherproof
environment. An optional fascia overlay hood is available which improves the IP rating
to IP65.
• Do not mount the control unit on a structure that is subject to vibration, or in a position
where damage may be caused by impact, thermal stress, or liquid ingress.
• Where three of more units are fitted in the same cabinet or panel, ensure that there is
adequate air circulation to aid cooling. It is recommended that an air circulation fan be
fitted.
• The control unit requires at least 6.5-in. (165 mm) clearance behind the mounting
panel to avoid cable fouling.
• After mounting the control unit, all wiring is made at the rear of the unit using the two
part terminal blocks provided. (A pre-wired data download socket suitable for front
panel mounting is provided on the Rosemount 3493 Control Unit).
• Mount the control unit on a panel with thickness 1.5 to 10 mm, ensuring the panel is
strong enough to support the 2.6 lb. (1.2 kg) weight of the unit.
• Ensuring there is enough clearance behind the chosen position in the panel (6.5-
in./165 mm minimum), cut a horizontal slot 5.43-in. (138 mm) long by 2.68-in. (68
mm) high in the panel and remove any rough edges.
Related information
Accessory
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3.2.3 Installation guidelines for the IP-rated wall mount version
Figure 3-2: IP-rated Wall Mount
• This housing is rated IP65. It is suitable for mounting outside, but this should be above
any flood level, away from any overflow path, and away from direct sunlight.
• Do not mount the control unit on a structure that is subject to vibration, or in a position
where damage may be caused by impact, thermal stress, or liquid ingress.
• The mass of the mains powered unit is 1.4 kg, and the dc powered unit is 1.0 kg. To
conform with safety requirements, the wall on which the unit is mounted should be
capable of supporting four times this weight.
• It is not necessary, or advisable, to remove the upper part of the unit housing that
contains the LCD display and keypad. There are no user serviceable parts inside. The
control unit must not be modified in any way.
3.2.4 Installation guidelines for the NEMA 4X-rated wall mount version
Figure 3-3: NEMA 4X-rated Wall Mount
• This housing is rated NEMA 4X. It is suitable for mounting outside, but this should be
above any flood level, away from any overflow path, and away from direct sunlight.
• Do not mount the control unit on a structure that is subject to vibration, or in a position
where damage may be caused by impact, thermal stress, or liquid ingress.
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• The mass of the mains powered unit is 3.5 kg, and the dc powered unit is 3.1 kg. To
conform with safety requirements, the wall on which the unit is mounted should be
capable of supporting four times this weight.
• It is not necessary, or advisable, to remove the upper part of the unit housing that
contains the LCD display and keypad. There are no user serviceable parts inside. The
unit must not be modified in any way.
• Control units are not supplied with cable entries for connections to the field mounted
transmitter or the mains power supply. However, the Rosemount 3493 Control Unit
has a download socket factory pre-fitted.
• It is the responsibility of the user to ensure that cable glands and connection to the
control unit are in accordance with the local or national standards. To maintain the
type 4X rating of the enclosure, type 4X connections must be used.
3.3 Mounting the control unit
3.3.1 Mounting the panel version
Procedure
1. Unpack the two screw clips provided.
2.
Identify the lugs (protrusions) in the recesses on each side of the control unit.
(Ignore the recesses on the top and bottom of the control unit).
3. Holding the screwdriver-slot-end of the threaded spindle of one of the screw
clamps and looking at the control unit rear, engage a screw clamp frame onto the
control unit side (see Figure 3-4) and see how the four steel lugs (protrusions) of the
screw clamp frame engage with the lugs of the control unit. Gently pull the screw
clamp for the lugs to engage with each other.
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Figure 3-4: The Fitted Screw Clamp
A. Screw clamp frame
B. Front panel bezel
C.
Screw clamp with threaded spindle
4. Remove the screw clamps from both of the screw clamp frames.
5. Slide the control unit into the panel, ensuring that the panel seal provided is in place
behind the front panel bezel.
6.
Re-fit the screw clamps, one on each side, and tighten with a screwdriver to clamp
the control unit against the panel.
Postrequisites
Make the electrical connections.
Related information
Installation guidelines for the panel mount version
Making electrical connections on panel-mount units
3.3.2 Mounting the IP-rated wall mount version
Procedure
1. Mount the unit on a suitable wall or structure using the fixing points.
2. Make the electrical connections.
Related information
Installation guidelines for the IP-rated wall mount version
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Dimensional drawings
Making electrical connections on wall-mount units
3.3.3 Mounting the NEMA 4X-rated wall mount version
Procedure
1. Mount the unit on a suitable wall or structure using the fixing points.
2.
Make the electrical connections.
Related information
Installation guidelines for the NEMA 4X-rated wall mount version
Dimensional drawings
Making electrical connections on wall-mount units
3.4 Electrical installation
WARNING
It is the responsibility of the installer to:
Refer to safety data and electrical specifications in Specifications and reference data.
Refer to the certifications and control drawings in Product certifications.
Check and obtain any work permits required before applying power to the unit.
Observe all local regulations and approval requirements.
Ensure the wiring is suitable for the load current.
Ensure the wiring insulation is suitable for the voltage, temperature, and environment of
the installation.
Drill holes in the base of the NEMA® 4X-rated control unit for fitting cable glands.
Ensure suitable cable glands or conduit connections are used when wiring to the control
unit to maintain enclosure integrity.
Never remove or modify the mechanical barriers separating the terminal area from the
main enclosure and separating the transmitter input terminals from other terminals.
3.4.1 Making electrical connections on wall-mount units
Note
Use only 167 °F (75 °C) copper conductors for field wiring.
All field wiring connections are accessible by removing the lower terminal cover, which is
secured by two screws on the IP-rated version and by four screws on the NEMA 4X rated
version.
The cabling between the Rosemount 3490 Series Control Unit (“control unit”) and a
transmitter should be a screened (shielded), twisted-pair type with the cable screen
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(shield) connected to terminal 3 (marked with earth/ground symbol) on the control unit.
The cable screen (shield) should be left unconnected at the transmitter end unless there is
a terminal specifically provided for this purpose.
Cable runs should be separate from any high voltage or mains cables to avoid crosstalk or
interference.
Figure 3-5 shows the layout of the control unit terminals. All terminal blocks are suitable
for wires 14 to 26 AWG (0.5 to 1.5 mm2), except the mains terminals which are suitable for
wires 10 AWG (2.5 mm2). Insulation should be stripped back ¼-in. (7 mm).
Figure 3-5: Connection Terminals Layout (for Mains-Powered Wall-Mount Unit)
The dc powered unit has a slightly different layout – terminals 31 and 32 replace terminals
28 and 29.
Transmitter connections are made on the left side of the terminals enclosure. Connecting
the intrinsically safe earth/ground (terminal 30) to a high integrity earth/ground point is
recommended if the transmitter connected to terminals 1 and 2 is in a hazardous area
Note
In intrinsically safe systems, apparatus connected to the Rosemount 3490 Series Control
Unit must not be supplied from a voltage greater than 250 V r.m.s. or 250 Vdc.
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Table 3-1: Connection Terminal Descriptions (Wall-mount Control Unit)
Terminal Function Terminal marking
1 Loop supply 24V
2 Current input Iin
3 Cable screen Earth (Earth symbol)
4-6 RS232 RX-TX-0V
7-9 Current output 24V-Iout-0V
10-12 Digital input 1 and 2 IN1-IN2-0V
13-15 Relay 1 NO-COM-NC
16-18 Relay 2 NO-COM-NC
19-21 Relay 3 NO-COM-NC
22-24 Relay 4 NO-COM-NC
25-27 Relay 5 NO-COM-NC
(1)
28-29
Mains input L-N
30 I.S. Earth/Ground (Earth/Ground symbol)
(2)
31
(2)
32
(1) Mains-powered control unit only
(2) Direct current (dc) powered control unit only.
Negative -
Positive +
Cable glands for the IP-rated wall-mount unit
The five cable-entry positions are pre-drilled to accept M20 cable glands. The Rosemount
3493 Control Unit has a data download socket factory pre-fitted in one of these cableentry positions.
Two cable glands, rated IP65 and suitable for cable with outside diameter 4 to 7 mm, are
supplied for use with the mains supply and transmitter cable. M20 blanking plugs are
supplied for the other three cable entry positions.
All glands and blanking plugs are supplied in a plastic bag. The installer must fit these, or
suitable equivalents, in place of the transit red-caps, to ensure weatherproofing of the
control unit.
The white sealing washers (supplied in the plastic bag) must be fitted on the outside of the
enclosure under the blanking plugs.
Related information
RS232 connections
Cable gland and conduits for the NEMA 4X-rated wall-mount unit
The Rosemount 3493 Control Unit has a data download socket factory pre-fitted.
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Refer to the Rosemount 3490 Series Quick Start Guide for information about where holes
can be drilled for fitting cable glands.
Related information
RS232 connections
3.4.2 Making electrical connections on panel-mount units
Field wiring connections are made to the back of the panel-mount control unit using the
two-part (plug/socket) terminal connectors provided. Figure 3-6 shows the rear panel.
Note
The plug/socket terminal connectors on the panel mount unit are polarized (keyed) to
prevent inter-changeability and incorrect connection.
Figure 3-6: Connection Terminals Layout (Mains-powered Panel-mount Unit)
The dc powered control unit has a slightly different layout – terminals 31 and 32 replace
terminals 28 and 29.
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Table 3-2: Connection Terminal Descriptions (Panel-mount Control Unit)
Terminal Function Terminal marking
1 Loop supply 24V
2 Current input Iin
3 Cable screen Earth (Earth symbol)
4-6 RS232 RX-TX-0V
7-9 Current output 24V-Iout-0V
10-12 Digital input 1 and 2 IN1-IN2-0V
13-15 Relay 1 NO-COM-NC
16-18 Relay 2 NO-COM-NC
19-21 Relay 3 NO-COM-NC
22-24 Relay 4 NO-COM-NC
25-27 Relay 5 NO-COM-NC
(1)
28-29
Mains input L-N
30 I.S. Earth (Earth symbol)
(2)
31
(2)
32
(1) Mains-powered control unit only
(2) Direct current (dc) powered control unit only
Negative -
Positive +
Cabling between the Rosemount 3490 Series Control Unit (“control unit”) and a
transmitter should be a screened (shielded), twisted-pair type with the cable screen
(shield) connected to terminal 3 (marked with earth/ground symbol) on the control unit.
The cable screen (shield) should be left unconnected at the transmitter end unless there is
a terminal specifically provided for this purpose. Cable runs should be separate from any
high voltage or mains cables to avoid crosstalk or interference.
Connect terminal 30 (intrinsically safe earth/ground) to a high integrity earth/ground
point if the transmitter connected to terminals 1 and 2 is in a hazardous area. This is a
special condition for some intrinsically safe approvals.
Related information
Product certifications
3.4.3 Power connections
When the control unit is powered by mains alternating current (ac) power, select the
voltage as 115 V or 230 V using the voltage-selector slide switch.
When the control unit is direct current (dc) powered, ensure the supply is adequate (15 to
30 Vdc). Do not exceed 30 Vdc.
A switch or circuit breaker should be installed in close proximity to the instrument, and
labeled as such. Although the Rosemount 3490 Series Control Unit meets all European
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January 2022 00809-0100-4841
standards for surge immunity on power and signal lines, it is recommended that lightning
suppressors are also fitted if local conditions make this advisable.
3.4.4 Earthing connections
The IP-rated Rosemount 3490 Series Control Unit is double insulated and does not require
a mains earth.
Note
Do not connect terminal 30 to a mains earth. Terminal 30 is provided for use as an
intrinsically safe (or functional) earth connection, which must be used when a transmitter
is mounted in a hazardous area and is connected to terminals 1 and 2.
Terminal 3 is to be used for connection of a twisted-pair cable screen (shield) when the
control unit is powering the transmitter. This screen (shield) should be left unconnected at
the transmitter end unless there is a terminal provided for this purpose.
On the NEMA 4X-rated control unit, protective earth cables must be connected to at least
one of the bonding points on the inside of the enclosure. Bonding between cable/conduit
entries is not automatic and must be provided as part of the installation.
When connected to equipment located in a hazardous area, not meeting the
requirements of clause 6.3.13 (Isolation of circuits from earth or frame) in IEC
60079-11:2006 (EN 60079-11:2007), equipotential earthing must be ensured between
the equipment and the intrinsically safe earth. An example of equipotential earthing is a
cable with a cross-sectional area greater than 4 mm2 and a resistance of less than 1 ohm.
Related information
Transmitter connections and cabling
3.4.5 Transmitter connections and cabling
Connection of a transmitter to the control unit does not confer intrinsic safety on the
transmitter. It is the responsibility of the user to ensure any transmitter installed in a
hazardous area is suitable for use and certified accordingly. The installation should be in
accordance with a recognized code of practice.
Check that the electrical parameters of the installed system of control unit, transmitter,
any loop-powered devices, and interconnecting cable to ensure compliance with the
product certificates and technical data. Particular attention must be given to the cable and
the transmitter to ensure that the total capacitance and inductance limits stated in the
technical data in Product certifications are not exceeded.
Cable joins are allowable in cabling the transmitter, provided that the joint is made within
an IP20/NEMA 3 (minimum) enclosure suitable for the environment, and that wiring
withstands a test voltage of 500 V r.m.s. to earth.
The maximum length of cable permissible between the transmitter and control unit is
determined by limits imposed by the intrinsic safety certificates of the instruments and
control drawings.
No other outputs from the control unit must be routed through a hazardous area unless
protected by an additional I.S. Barrier (not supplied).
28 Emerson.com/Rosemount
1
2
3
A
24 V
I
IN
B
1
2
3
A
B
24 V
I
I
N
Reference Manual Installation
00809-0100-4841 January 2022
It is the responsibility of the user to ensure that any transmitter is installed in accordance
with the manufacturer’s instructions supplied with the transmitter.
Cable between the control unit and the transmitter should be shielded twisted-pair with
the shield connected to terminal 3 (marked with earth symbol) on the control unit.
The shield should be left unconnected at the transmitter unless there is a terminal
specifically provided for this purpose.
Cable runs should be separate from any high voltage or mains cables to avoid crosstalk or
interference. Multi-core cable may be used if the other cores carry only low voltage (24
Vdc nominal) signals and each pair of cores is individually screened (shielded).
Loop-powered transmitters must be connected to terminals 1, 2, and 3 on the control unit
(see Figure 3-7).
Figure 3-7: Loop-powered Transmitter Connections
A. Control unit
B. Transmitter
The control unit supplies 23 Vdc from a 400 Ohm source to power transmitters. Separately
powered transmitters must be connected to terminals 2 and 3 (see Figure 3-8).
Figure 3-8: Self-powered Transmitter Connections
A. Control unit
Transmitter
B.
Emerson.com/Rosemount 29
1
2
3
1
2
3
A
B
A
B
C
Installation Reference Manual
January 2022 00809-0100-4841
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 (Figure 3-9), or
• 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).
Figure 3-9: Connecting Two HART transmitters
A. HART transmitter Tx1
B. HART transmitter Tx2
Junction box
C.
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. With the power supply turned off, connect the first HART transmitter to the
Current Input terminals on the control unit.
2. Check the voltage-selector-switch is set for the correct voltage on the mainspowered control unit (115 or 230 Vac), and then turn the power on.
30 Emerson.com/Rosemount
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