MSA SENTRY io User manual

Operating Manual
SENTRY io®
Wall Mount Controller
Order No.: 10225296/02
Print Spec: 10000005389 (R)
CR: 800000061840
MSAsafety.com
US

© MSA 2023. All rights reserved
WARNING!
These instructions must be provided to users before use of the product and retained for ready reference by the user. Read this manual carefully before
using or maintaining the device. The device will perform as designed only if it is used and maintained in accordance with the manufacturer's
instructions. Otherwise, it could fail to perform as designed, and persons who rely on this device could sustain serious injury or death.
The warranties made by MSA with respect to the product are voided if the product is not installed and used in accordance with the instructions in this
manual. Please protect yourself and your employees by following the instructions.
Please read and observe the WARNINGS and CAUTIONS inside. For additional information relative to use or repair, call 1-800-MSA-2222 during
regular working hours.
MSA is a registered trademark of MSA Technology, LLC in the US, Europe and other Countries. For all other trademarks visit
https://us.msasafety.com/Trademarks.
1000 Cranberry Woods Drive
Cranberry Township, PA 16066
USA
Phone: 1-800-MSA-2222
Fax: [phone]
For your local MSA contacts, please go to our website www.MSAsafety.com

US SENTRY io 3
Contents
1 Safety Regulations 5
1.1 Liability 5
1.2 Warnings 5
1.3 Correct Use 6
2 Overview 7
2.1 Components 7
2.2 Control Unit 8
2.2.1 Wall Mount Enclosure 8
2.2.2 Power Supply 8
2.2.3 CPU and HMI Touchscreen Panel 9
2.2.4 Buzzer 9
2.3 Input and Output Devices 9
2.3.1 Input Power Sources 9
2.3.2 Input Devices Compatibility 10
2.3.3 Output Devices Compatibility 11
2.3.4 Gas Reading Conversion 13
2.3.5 Faults 13
2.4 Power Source Compatibility and Budgeting 13
2.4.1 Power Compatibility 13
2.4.2 Power Budgeting—Connected Field Device Power Allocation Calculation 13
2.5 Installation Recommendations 13
2.6 Field Cabling 14
2.7 Configuration and Programming 14
3 Installation 16
3.1 Warnings 16
3.2 Preparing for Installation 16
3.3 Mechanical Installation 16
3.3.1 Mounting Guidelines 16
3.3.2 Wire Entry Penetrations 17
3.4 Electrical Installation 17
3.4.1 Electrical Power Supply Requirements 17
3.4.2 Electrical Installation Procedure 18
3.5 Communications 18
3.5.1 Modbus TCP 18
3.5.2 Modbus RTU (RS485 Serial)—Optional 18
3.5.3 Device Level Ring (DLR) 20
3.6 Remote Displays 20
3.7 Wiring and Grounding 20
3.8 Relay Outputs 21
4 Configuration 22
4.1 General Settings 22
4.1.1 Setting the System Language 22
4.1.2 Setting the Date and Time 22
4.1.3 Setting the Communication Information 23
4.1.4 Setting the Administration Password 24
4.2 Input/Output Configuration 24
4.3 Detectors and Alarm Setpoints 24
4.3.1 Auto Identifying Detectors 24
4.3.2 Manually Identifying Detectors 25
4.3.3 Detectors Summary 25

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4.3.4 Alarm Set-points 26
4.4 Digital Inputs 27
4.5 Relays 28
4.6 Voting Zones 29
4.7 Cause and Effect 30
5 System Verification 31
6 Operation 32
6.1 Dashboard 32
6.1.1 Viewing Detector Details 32
6.1.2 Inhibiting or Activating Digital Inputs 34
6.1.3 Acknowledging, Silencing, and Resetting Alarms 34
6.1.4 Viewing the Alarm Summary 35
6.2 Tools 35
6.2.1 Updating the Dashboard View 35
6.2.2 Changing the System Language 35
6.2.3 Updating the Communication Type 36
6.3 Settings 36
6.3.1 Modifying the Configuration 36
6.3.2 Updating the General Settings 36
6.3.3 Backing Up the Database 37
6.3.4 Restoring the Database 37
6.3.5 Resetting the Configuration 37
6.4 SD Card 37
6.5 Software Update Process 37
7 Technical Specifications 38
8 Maintenance 40
8.1 Periodic Functional Test 40
8.2 Calibration Check 40
8.3 Cleaning 40
8.4 Storage 40
9 Troubleshooting 41
10 Ordering Information 44
10.1 Controller 44
10.2 Accessories/Spare Parts 44
11 MSA Permanent Instrument Warranty 46
12 Resources 47
12.1 Cause and Effect Planning 47
12.2 Power Consumption Calculation 47
12.3 Modbus Address List 47

1 Safety Regulations
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1 Safety Regulations
Read this manual carefully before using the SENTRY io. The SENTRY io will perform as designed only if it is used and
maintained in accordance with the manufacturer's instructions. Otherwise, it could fail to perform as designed and persons
who rely on the SENTRY io for their safety could sustain serious personal injury or death.
The warranties made by MSA with respect to the product are voided if the product is not installed and used in accordance
with the instructions in this manual. Please protect yourself and your employees by following the instructions. Read and
observe the WARNINGS and CAUTIONS inside.
Make sure any personnel who will be installing, using, or maintaining the SENTRY io have access to the user manual. If
electronic access to the user manual is not possible, print a copy of the manual and keep it in an accessible location near
the SENTRY io. Failure to obey the following guidelines and/or incorrect installation, operation, servicing, or maintenance
of the SENTRY io can cause incorrect operation of the control unit.
1.1 Liability
MSA accepts no liability in cases where the device has been misused, used inappropriately or not used as intended. MSA
accepts no liability in cases where damage or injury is caused by wear and tear, neglect or failure to carry out inspection
and maintenance procedures. The selection and use of the device are the exclusive responsibility of the employer and/or
individual operator. Warranties and guarantees made by MSA with respect to the device are voided, if it is not used,
serviced or maintained in accordance with the instructions in this manual.
1.2 Warnings
WARNING!
lInstall, operate, and maintain the SENTRY io in strict accordance with its labels, cautions, warnings, instructions, and
stated limitations.
lFor any maintenance procedure provided in this manual, use only genuine MSAreplacement parts. Repair or
alteration of the SENTRY io beyond the scope of these maintenance instructions or by anyone other than authorized
MSAservice personnel can cause incorrect operation of the SENTRY io. See 10 Ordering Information for available
parts.
lWiring procedures described in this manual are intended for proper functioning of the devices under normal
conditions. Always be certain that all wiring and equipment installation meets or exceeds the latest revisions of the
appropriate National Standards, Electrical Codes and all local ordinances. If in doubt, consult the Authority Having
Jurisdiction (AHJ) before wiring the system.
lNever operate the SENTRY io without a connection to Earth ground. Failure to connect the device to Earth ground
can result in electrical shock. Electrical shock can cause damage to the SENTRY io and injury to personnel.
lDo NOT use the SENTRY io in hazardous environments beyond the limits indicated on the product label.
lNo internal power shut-off switch, breaker, or fuse is provided within the SENTRY io enclosure. An externally located
power shut-off switch or breaker is recommended to enable removal of power from the system.
lSome devices and components covered within this document may contain semiconductor devices susceptible to
damage by electrostatic discharge. An electrostatic charge can build up on the skin and discharge when an object is
touched. Always observe normal precautions for handling electrostatic sensitive devices, such as use of a wrist strap
(if available) and proper grounding, when installing the equipment described within this manual.
lExternal alarms and other mitigation devices must be disconnected prior to performing system tests to avoid causing
interruption to facility operations. Ensure that external alarms and other mitigation devices are reconnected
immediately after system testing.
lDo not exceed the relay contact rating listed in 7 Technical Specifications or relay operation may fail.
lFor all devices connected to the SENTRY io, review and follow the device manuals for guidance and instruction on
inspection, calibration, operation, and maintenance.
Failure to follow these warnings can result in serious personal injury or death.

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1 Safety Regulations
1.3 Correct Use
The SENTRY io is a wall-mount multi-channel controller intended for use with MSA fixed gas detection devices. The
controller is housed within a fiberglass enclosure along with the system power supply, input/output modules, field wiring
terminals, and a graphic user interface screen with touch-panel and buzzer.
The SENTRY io is designed to accept standard 4-20 mA analog signal inputs from connected MSA or generic gas
detectors and will also accept discrete inputs from contact closure devices such as switches or relay contacts. The system
provides discrete relay outputs for use in energizing notification devices such as sounders, strobes, or horns. Optional
analog 4-20 mA outputs are also available when specified. All systems include an internal field wiring termination strip to
enable easy connection of interconnecting field wiring conductors.
The SENTRY io enclosure door needs to remain closed during operation of the unit.
The SENTRY io graphic user interface (GUI) with touchscreen provides the SmartStart configuration wizard enabling easy
configuration of user language, date/time, connected gas detectors, discrete input and output signals, and user-specified
cause & effect operating logic.
Multiple SENTRY io system configuration options are available depending upon the number and type of input/output
channels required.
WARNING!
This product is supporting life and health. Inappropriate use, maintenance, or servicing may affect the function of the
SENTRY io and thereby seriously compromise the user’s life.
Do not operate the SENTRY io beyond the limits specified in 7 Technical Specifications.
Before use, the product operability must be verified. The product must not be used if the function test is unsuccessful, the
product is damaged, a competent servicing/maintenance has not been made, or genuine MSA spare parts have not been
used. See 5 System Verification and 8 Maintenance for more information.
Failure to follow this warning can result in serious personal injury or death.

2 Overview
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2 Overview
2.1 Components
1Buckle 8Analog input terminations
2SD card, Ethernet ports, USB 9Digital input terminations
3Gasket 10 Modules
4Fan bracket 11 Power supply
5Hinge 12 Relays
6PLC / HMI 13 Power
7Buzzer 14 Analog output

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2 Overview
2.2 Control Unit
2.2.1 Wall Mount Enclosure
The SENTRY io:
lis housed in a fiberglass enclosure with dimensions of 558.8 mm x 447.68 mm x 241.3 mm (22 in x 17.62 in x 9.5in)
lhas pre-configured holes provided on the bottom surface of the enclosure (for ¾” NPT knockout or M20)
lis mounted by four screws (10-32 or M4).
2.2.2 Power Supply
lThe 24 VDC, 10A power supply accepts main AC power.
lThe SENTRY io uses a COSEL power supply (PN: KHNA240F-24) or equivalent - for specifications, please refer to
the COSEL product page.
lThe COSEL KHNA240F-24 complies with SELV requirements as per UL 60950-1 and OSHA Class I Div. 1
requirements.
lBattery backup is an available option.
Backup Battery
The SENTRY io has an optional battery back-up package available from MSA. Consult the factory for pricing and
availability. This battery back-up cabinet provides approximately 1 hour of battery run-time upon AC failure.
This battery back-up package is contained in its own enclosure and requires an interconnection between the main
SENTRY io cabinet and the battery back-up cabinet. The details of that interconnection are shown below:

2 Overview
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External Provided Power Supply
It is possible to power the SENTRY io using an external power supply. Contact the factory for details on how to implement
an external power supply.
2.2.3 CPU and HMI Touchscreen Panel
The integrated CPU and 7" HMI touchscreen mounted in the enclosure door and include:
lCPU/Logic Solver
l7" HMI touchscreen display (800x480 WVGA)
l16 GB microSD Memory Card
l(1) Ethernet port for Modbus TCP/IP, MSA Cloud connection, remote display, or Ethernet IP connections
NOTE: If a supplemental Ethernet port is installed on the HMI panel for additional communications, the base unit
PLC Ethernet cable must be moved to the last element (supplemental port).
If more than one physical Ethernet port is required, then use a supplemental Ethernet switch.
The front panel enables communication with the SENTRY io through the touchscreen and is used to:
lmonitor the status of all connected detectors
lconfigure all settings
lprovide alarm and fault histories
lallow gas trending over time
2.2.4 Buzzer
The SENTRY io buzzer is designed to audibly alert you when an event occurs. The buzzer is not intended to be the primary
indicator of an alarm condition.
The buzzer has distinct tones for both alarm and fault:
lAlarm—Steady tone
lFault—Intermittent tone (1 second on, 1 second off)
The buzzer dial allows for volume adjustment. To adjust the buzzer dial, spin the tabs
on the inside of the buzzer dial.
NOTE: Buzzer volume level should be adjusted for ambient environment noise level.
2.3 Input and Output Devices
The SENTRY io responds to inputs and executes outputs in less than one second. The SENTRY io will also report any fault
condition or a failure in its internal communication in the same one-second time frame.
NOTE: The response time of the SENTRY io is dependent on the instrumentation connected to it.
2.3.1 Input Power Sources
The SENTRY io is designed to accept 120 VAC or 240 VAC input power sources. The input power wiring termination
blocks are located in the lower right hand corner of the panel. The installer should land the main AC power source at the
proper VAC input terminals shown below. All other internal VAC and VDC power distribution wiring is factory installed.

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2 Overview
If employing the optional battery backup, consult the factory.
2.3.2 Input Devices Compatibility
Analog Inputs
The SENTRY io is designed to provide 24 VDC field device power for connected, 2 and 3-wire 4-20 mA signal fixed gas
detectors. The wiring termination blocks for connected gas detectors are located in the lower left hand corner of the panel.
These inputs utilize a three-tier terminal block See the figures below for location and typical wiring connection.

2 Overview
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Digital Inputs
The SENTRY io also supports connection to discrete dry contact (on/off) input devices. These inputs are 24 VDC input
signals. The wiring termination blocks for discrete input device connections are located to the right of the 4-20 mA signal
input terminal blocks and utilize a two-tier terminal block. The SENTRY io enables the internal 24 VDC power to be used for
the discrete 24 VDC signal inputs. See the figures below for location and typical wiring connection.
NOTE: Input 1/9 is pre-programmed for Remote Silence and input 2/10 is pre-programmed for Remote Reset. The balance
of discrete inputs are user configurable in the SmartStart configuration wizard.
2.3.3 Output Devices Compatibility
The SENTRY io provides relay contact outputs for energizing external devices and equipment when an alarm or fault
condition is identified. The SENTRY io relay contact outputs can switch either 24 VDC provided by the internal power
supply or from a user-supplied external power source. See the figure below to identify dry and wetted/powered pre-wired
contacts:
Module 1, relays 1-4 are dry contacts.

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2 Overview
lRelay 1 is pre-programmed as common alarm
lRelay 2 is pre-programmed as common fault
lRelays 3 and 4 are user configurable
NOTE: The SENTRY io provides only normally de-energized relay coils. The only exception is the common fault relay
which is normally energized.
The SENTRY io comes pre-wired with all contacts dry except for relays 5-8 (which includes the buzzer on relay 5). To add
additional powered relays, you need to connect 0 VDC and 24 VDC to the terminal strip as shown below. Powered contacts
are used for things like horn and strobe activation.
Module 2, relays 5-8 are powered contacts.
This image displays the existing pre-wired powered
contacts.
This image displays the typical modifications to provide
additional powered contacts. The highlighting indicates the
customer-added wiring.
The SENTRY io also supports optional analog 4-20 mA signal outputs. These signals are current sources and should be
used with sinking signal receivers only. These signal outputs are used to retransmit the analog input signals to another
control system. These analog outputs are a 1:1 mapping of all the input analog signals to the SENTRY io. Analog signal
outputs are sourced using the internal 24 VDC power supply.
Analog Outputs

2 Overview
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2.3.4 Gas Reading Conversion
Combustible, toxic, and oxygen gas readings use the following equation:
Gas Reading = [(Io-4)/16] * DU * DP
DU: Display Units
DP: Decimal Positon - Resolution of the gas reading
2.3.5 Faults
The Sentry io displays a general sensor fault when the gas detector analog value dips into fault condition. This fault is
shown on the home screen and in the alarm log with a time stamp.
For MSA’s HART enabled detectors, certain fault codes are shown in the Sentry io diagnostics tab for the detector. These
fault codes should be referenced against the MSA instrument's instruction manual for the relevant fault code explanation.
The Sentry io also shows a general fault if there is an internal error or PLC failure.This fault is shown on the home screen
and in the alarm log with a time stamp.
2.4 Power Source Compatibility and Budgeting
2.4.1 Power Compatibility
SENTRY io is available with a factory-installed 24 VDC power supply compatible with main power sources as described in
7 Technical Specifications.
Ensure your system does not exceed rated total current output capacity of the 24 VDC power supply.
2.4.2 Power Budgeting—Connected Field Device Power Allocation Calculation
The SENTRY io internal power supply is provided to enable powering 24 VDC field input and output devices connected to
the panel. The SENTRY io internal modules will consume a certain portion of the available amperage. In all cases, the user
must ensure the total amperage load of all connected input and output devices do not exceed the remaining amperage
capacity of the SENTRY io power supply.
Calculate total power requirements of all connected analog signal input devices and total 24 VDC power load of all
connected output devices from cold start. The sum total power draw of all connected input and output devices must not
exceed unallocated, available amperes of available 24 VDC power. Use the power consumption worksheet in the SENTRY
io Online Help to calculate the power load requirements and available budget for field devices.
NOTE: If the SENTRY io relay output contacts will be switching DC or AC power supplied from an external source, these
power loads will not be included in your calculation.
2.5 Installation Recommendations
For SENTRY io installation, MSA recommends the following:
lOnly located in areas that comply with SENTRY io specifications. See 7 Technical Specifications.
lLocated in areas that allow for easy access to the touch screen and internal components as necessary to configure,
view, and service.
lAccess to open the door
lAccess to power source, breaker, etc.
lAccess to field cabling trays/exit points—select location with consideration to wiring routes
lOut of direct sunlight
NOTE: The SENTRY io internal temperature can depend on system electrical load as well as thermal loading from
direct sunlight. It is best to not mount in direct sunlight or near other excessive heat sources.

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2 Overview
2.6 Field Cabling
Adhere to local building codes and individual field device recommendations when wiring the SENTRY io on site.
Cable shielding for all input and output devices must be connected to SENTRY io chassis ground.
NOTE: SENTRY io terminal blocks can accept a maximum wire gauge of 12 AWG and a minimum gauge of 18 AWG, one
wire per terminal.
lEarth ground—Make solid ground connection to one of the panel ground lugs
lPanel power input cabling
o120 or 220 VAC acceptable
oOrange power shut-off knife switch is included within panel power terminals
lField device signal input cabling
oAnalog 4-20mA current signals—Recommended type is stranded copper 3-conductor with overall foil shield
NOTE: Do not exceed the maximum loop impedance of the analog input and analog output channels listed in 7
Technical Specifications.
oDiscrete Input signals—Recommended type is stranded copper 2-conductor
lField device output cabling
oRelay output signals—Recommended type is stranded 2-conductor with overall foil shield
NOTE: Be aware of voltage drop on DC cable runs. Select proper cable size to prevent excessive voltage
drop.
oAnalog 4-20mA current signals—Recommended type is stranded copper 3-conductor with overall foil shield
lDigital Communications cabling
oModbus RTU—Should utilize a twisted shielded cable. Belden 3105A cable or similar cable is acceptable.
oModbus TCP/IP—Should utilize CAT 6 Ethernet cables
oDevice Level Ring (DLR)—Can be implemented using either copper or fiber media. Contact MSA Customer
Support for assistance with DLR implementations.
lExpansion enclosure cabling may be required
2.7 Configuration and Programming
System configuration and programming is accomplished using the SmartStart configuration wizard on the 7-inch
touchscreen located on the door of the SENTRY io panel. To simplify configuration and programming of your system, it is
recommended to plan and document each of the following identifiers for all connected field devices and operational
relationships between each input and output device:

2 Overview
US SENTRY io 15
lAnalog Input Device Identifiers include:
oChannel # for each field device
oTag name for each field device (maximum characters: 11)
oLocation description (maximum characters: 11)
oType of field device (examples include comb gas detector, toxic gas detector, low O2 detector, Open Path,
etc.)
oType of Gas to be detected (examples include methane, propane, H2S, HF, etc.)
oUnits of Measurement (examples include % of LEL, PPM, % Volume, LEL-M, etc)
oFull Scale of Measurement (examples include 100 %LEL, 100 PPM, 50 PPM, 25 PPM, 5 LEL-M, etc)
oAlarm Levels 1 (low), 2 (medium), and 3 (High) setpoints for input devices in proper units and measurement
scale
lDigital Input Device Identifiers include:
oInput Channel #
oInput Tag Name
oInput Enabled or Disabled
oInput Latching or Non-latching
lRelay Output identifiers include:
oRelay Module and Channel #
oRelay Name
oRelay Description
lRelay Zone Voting Requirements
oIf selected, user must define Voting Zones required and names of each Zone
oUser must define which Discrete signals and Analog Alarm signals shall be evaluated within Zone voting logic
For assistance, use the Cause and Effect Planning spreadsheet in the SENTRY io Online Help to do your cause and effect
pre-planning.

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3 Installation
3 Installation
3.1 Warnings
WARNING!
lA qualified electrician must do electrical wiring.
lAll wiring must comply with all applicable NEC/CEC and local electrical safety codes.
lTo prevent electrostatic discharge (ESD), connect an ESD wrist strap to the ESD connection point inside the
SENTRY io enclosure before doing work inside the enclosure. ESD can damage the SENTRY io.
lThe input/output modules are NOT field serviceable. Do NOT disassemble or modify the modules.
lDo NOT install or operate the SENTRY io if it is damaged.
lDisconnect AC power before opening the SENTRY io enclosure. Failure to do so can result in electrical shock.
Electrical shock can damage the SENTRY io and injure personnel.
lEnsure the enclosure door seal is free from debris before closing and latching the SENTRY io door.
lNever operate the SENTRY io without a connection to ground. Failure to connect the device to ground can result in
electrical shock. Electrical shock can cause damage to the SENTRY io and injury to personnel.
lDo NOT use the SENTRY io in hazardous environments beyond the limits indicated on the product label.
lEnsure the SENTRY io is NOT located in areas that contain a flammable mixture of gas and air. Otherwise, an
explosion can occur.
Failure to follow these warnings can result in serious personal injury or death.
3.2 Preparing for Installation
Before installation, ensure the following:
lPackaging materials are removed from inside the SENTRY io
CAUTION!
Due to the weight of the SENTRY io, unpacking and removing it from the container may require an additional person to
assist.
Failure to follow this caution can result in minor or moderate injury.
lThe Quick Start Guide and film are removed from over the touchscreen
lModules are locked in place with no red displaying on the module locking tabs
lAll module and wiring terminal blocks are secured
lModule dust covers are secured
lBuzzer shutter is open or not dampened
lHinges and latches are intact and operational
lAll internal components are attached to a DIN rail
lEnclosure door seal is intact
NOTE: To prevent unauthorized or untrained personnel from opening the SENTRY io enclosure, it is recommended that
you install a locking mechanism through the metal loop on either latch on the right side of the device.
3.3 Mechanical Installation
3.3.1 Mounting Guidelines
When mounting the SENTRY io:

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US SENTRY io 17
lSelect a location that is easy to access and visible to personnel before they go into the area being monitored.
oDo not mount in direct sunlight or near other excessive heat sources
oAway from wet or damp conditions
oAway from areas that are dirty or exposed to oils or chemicals
NOTE: The SENTRY io requires programming and viewing the graphic user interface (GUI) from the touchscreen on
the front of the enclosure. It is recommended that the installation location selected enables easy viewing and
programming of the GUI.
lMount the enclosure to a wall or other rigid surface that is not prone to vibration or mechanical shock.
oApproximately 5 feet (1.5 meters) above the ground.
oWith at least 3 inches (about 8 cm) of clearance around all sides for proper ventilation, calibration, and
servicing. Ensure there is adequate space to connect the external wiring.
lUse hardware that is suitable for the mounting surface and can withstand 70 lb (32 kg) without loosening or causing
damage to the hardware or mounting surface. Use all four mounting holes provided on the SENTRY io.
3.3.2 Wire Entry Penetrations
For the SENTRY io wire entry penetrations:
lRemove the red plugs from the bottom of the enclosure
lEnsure holes are cleanly cut and can form an adequate seal as required for intended application
lInstall properly rated conduit, glands, or plugs as required for intended application.
NOTE: Drilling of additional holes is not recommended.
3.4 Electrical Installation
WARNING!
lA qualified electrician must do electrical wiring.
lWiring must comply with all applicable NEC/CEC and local electrical safety codes.
lNever operate the SENTRY io without a protective ground. Operating the SENTRY io without a protective ground
can result in electrical shock. Electrical shock can cause damage to the SENTRY io and injury to personnel.
lDisconnect AC power before opening the SENTRY io enclosure. Failure to do so can result in electrical shock.
Electrical shock can damage the SENTRY io and injure personnel.
lTo prevent electrical shock, avoid contact with electrical conductors and termination points when energized.
lTo prevent electrostatic discharge (ESD), connect an ESD wrist strap to the ESD connection point inside the
SENTRY io enclosure before doing work inside the enclosure. ESD can cause damage to the SENTRY io.
lDo not touch the electronic circuit boards.
lWhen closing and latching the SENTRY io door, ensure the enclosure door seal is free from debris and the door is
tightly sealed.
Failure to follow these warnings can result in serious personal injury or death.
3.4.1 Electrical Power Supply Requirements
The SENTRY io uses a power supply that accepts inputs of 100–240 VAC, 50/60 Hz, 200 VA maximum. Consider the
following recommendations:
lConnect the SENTRY io directly to the AC power source through a dedicated circuit breaker.
NOTE: Install either a standard 15 A circuit breaker or a 10 A slow–blow fuse.

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3 Installation
lUse an approved 3-conductor wire (minimum 14 AWG), rated 300 VAC at 221°F (105°C), to complete the AC power
connection.
lUse only conduit hubs and hardware that are suitable for fiberglass enclosures.
3.4.2 Electrical Installation Procedure
To wire the SENTRY io:
1. Disconnect electrical power.
2. Release the two latches on the right side of the SENTRY io and open the enclosure.
3. Attach the ESD wrist strap to the ESD connection point inside the enclosure.
4. Remove the AC power wiring hole plug.
5. Install conduit hubs that are suitable for fiberglass enclosures and rated for both environmental and hazardous areas
classifications.
6. Put the AC power wiring through the conduit.
7. Connect the AC power wiring to the #1 AC terminal block (HOT) and #2 AC terminal block (NEUTRAL) input
terminals. Make sure the connectors are seated securely.
8. Connect the AC power ground wire to the ground lug so the SENTRY io chassis ground is connected to the earth
ground.
9. Close the enclosure and latch the two latches.
10. Supply electrical power to the SENTRY io.
3.5 Communications
3.5.1 Modbus TCP
The SENTRY io comes standard with Modbus TCP communication. The Ethernet port is located on the side of the touch
screen inside the enclosure.
The SENTRY io Modbus address list includes addresses for discrete alarms, discrete inputs, relays, voting zones, system
faults, and analog. View this section in the SENTRY io Online Help to download the spreadsheet.
3.5.2 Modbus RTU (RS485 Serial)—Optional
The SENTRY io has an available Modbus RS485 capability by adding the optional communication module—P/N:
10221943.
The RS485 module clips on to the back of the SENTRY io touchscreen.

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US SENTRY io 19
Installing the Modbus RTU Module
1. Check the controller to verify that its COM jack is not covered.
2. Insert the module’s connection plug into the jack until it is firmly seated (as
shown).
This Modbus RS485 is unidirectional and provides diagnostic and alarm data about the SENTRY io's alarm faults and
detector status to third party systems (such as PLC, DCS systems). View the Resources section in the SENTRY io Online
Help to download the Modbus address list.
The Modbus RTU plug in module is shipped with a 4-pin RS485 terminal block. This connector is marked with a pin
assignment that is identical to the corresponding marking on the module. Termination should be made in accordance with
the diagram below.
RS485 Modbus Wiring Guidelines
lUse shielded twisted-pair cable in compliance with EIA RS485 specifications.
lWhen wiring each node, connect the cable shield to the functional ground point of the RS485 terminal block.
lIn order to avoid ground-loops, do not connect the RS485 functional ground terminal to the Earth of the SENTRY io
as it is internally connected to the SENTRY io's functional ground point.
RS485 Dip Switch Settings
Use the DIP switches shown in the table below to set the RS485. The device is shipped with both its DIP switches set to the
ON position; change settings to the OFF positions if there are no devices (PLC, HMIs, or DCSs) communicating on this
Modbus RTU network.

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3 Installation
3.5.3 Device Level Ring (DLR)
The SENTRY io can be configured to become a stand-alone node on an EtherNet/IP network using Rockwell Automations
device level ring (DLR) protocol. This DLR communication provides a fault tolerant self-healing ring network that is capable
of being run over Ethernet cable or multi-mode fiber optics.
This topology is detailed below, and can be utilized with MSA’s HazardWatch platform. Please consult the factory for
assistance with this configuration.
3.6 Remote Displays
SENTRY io has the ability to support a remote display over Ethernet. A remote display will act and function the same way
as the primary SENTRY io display. Both the primary and remote displays will have the ability to function simultaneously.
To establish a remote display you must install an Ethernet link between the main SENTRY io controller and the remote
display. This link can either be over CAT 6 cable (max distance 100 meters) or via multi-mode fiber optic cable (max
distance 2 km). If the single Ethernet is already being utilized for other communications (such as Modbus TCP/IP or MSA
Cloud connection) or you are using a fiber link, then a supplemental Ethernet Switch will need to be provided.
Remote Display Power
The remote display must be sourced with its own 24 VDC power source. This remote display draws 1 amp at 24 VDC.
Establish Communication
To establish communication between the SENTRY io and remote display, please contact MSA Customer Support.
3.7 Wiring and Grounding
Refer to the Installation Outline drawing (SK3015-1071) for details on the wiring requirements for the SENTRY io.
WARNING!
Ensure the SENTRY io chassis is connected to the earth ground at the groundlug.
Failure to follow this warning can result in serious personal injury or death.