Detcon CXT-IR User Manual

DETCON, Inc.

May 29, 2014 • Document # 3822 • Revision 1.6

Model CXT-IR

Operator’s Installation and Instruction Manual

Covers all Model CXT-IR Sensors

4055 Technology Forest Blvd, Suite 100

The Woodlands, Texas 77381

Ph.281.367.4100 / Fax [phone]

www.detcon.com

Model CXT-IR

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Model CXT-IR ii

Model CXT-IR

Table of Contents

1. Introduction ............................................................................................................................................... 1

1.1 Description .......................................................................................................................................... 1

1.2 Modular Design .................................................................................................................................. 3

1.2.1 CXT-IR Intelligent Tr ansmitter Module ........................................................................................ 3

1.2.2 Field Replaceable Sensor ................................................................................................................ 4

1.3 CXT Wireless Network ....................................................................................................................... 4

1.4 Battery Pack Options .......................................................................................................................... 5

1.4.1 Detconꞌs Smart Battery Pack .......................................................................................................... 5

1.4.2 Tri-C Lithium Battery Pack ............................................................................................................ 6

2. Installation .................................................................................................................................................. 8

2.1 Hazardous Locations Installation Guidelines for Safe Use ................................................................. 8

2.2 Sensor Placement ................................................................................................................................ 9

2.3 Sensor Contaminants and Interference ............................................................................................. 10

2.4 Sensor Mounting ............................................................................................................................... 10

2.5 Electrical Installation ........................................................................................................................ 12

2.5.1 Applying Power to the Unit .......................................................................................................... 13

2.6 Initial Start Up................................................................................................................................... 14

2.6.1 Combustible Gas Sensors ............................................................................................................. 14

3. Operation .................................................................................................................................................. 16

3.1 Operator Interface ............................................................................................................................. 17

3.1.1 Software Flowchart....................................................................................................................... 18

3.2 Normal Operation ............................................................................................................................. 19

3.3 Calibration Mode .............................................................................................................................. 19

3.3.1 AutoZero ....................................................................................................................................... 19

3.3.2 AutoSpan ...................................................................................................................................... 20

3.4 Program Mode .................................................................................................................................. 22

3.4.1 View Sensor Status ....................................................................................................................... 22

3.4.2 Set Gas Type ................................................................................................................................. 23

3.4.3 Set AutoSpan Level ...................................................................................................................... 23

3.4.4 Set Gas Factor ............................................................................................................................... 24

3.4.5 Bump Test .................................................................................................................................... 25

3.4.6 Restore Defaults ........................................................................................................................... 25

3.4.7 Set RF Channel ............................................................................................................................. 25

3.4.8 Set Modbus™ ID .......................................................................................................................... 26

3.5 Fault Diagnostic/Failsafe Feature ..................................................................................................... 26

4. Modbus™ TM Communications ............................................................................................................ 27

4.1 General Modbus™ Description ........................................................................................................ 27

4.1.1 Modbus™ Exceptions .................................................................................................................. 27

4.1.2 Modbus™ Broadcast Requests ..................................................................................................... 28

4.2 Modbus™ Register Map and Directions........................................................................................... 28

4.2.1 CXT Sensor Registers .................................................................................................................. 30

4.2.2 CXT Transceiver Registers .......................................................................................................... 31

5. Service and Maintenance ........................................................................................................................ 33

5.1 Replacement of the Batteries/Battery Pack ....................................................................................... 33

5.1.1 Units with 12V Smart Battery Pack.............................................................................................. 33

5.1.2 Units with Tri-‘C’ sized Lithium Battery Holder ......................................................................... 33

5.2 Replacement of Plug-in Sensor ......................................................................................................... 35

5.3 Replacement of ITM – Aluminum Junction Box .............................................................................. 35

5.4 Replacement of ITM – Stainless Steel Mini Condulet...................................................................... 36

6. Troubleshooting Guide ............................................................................................................................ 37

7. Customer Support and Service Policy ................................................................................................... 39

Model CXT-IR iii

Model CXT-IR

Shipping Address: 4055 Technology Forest, Suite 100, The Woodlands, Texas 77381

Phone: [phone] • Fax: [phone] •www.detcon.com •

8. CXT-IR Sensor Warranty ...................................................................................................................... 40

9. Appendix ................................................................................................................................................... 41

9.1 Specifications .................................................................................................................................... 41

9.1.1 System Specifications ................................................................................................................... 41

9.1.2 Environmental Specifications ....................................................................................................... 41

9.1.3 Electrical Specifications ............................................................................................................... 41

9.1.4 Mechanical Specifications ............................................................................................................ 41

9.2 Spare Parts, Sensor Accessories, Calibration Equipment ................................................................. 42

9.3 Revision Log ..................................................................................................................................... 43

Table of Figure s

Figure 1 Sensor Cell Construction ....................................................................................................................... 2

Figure 2 Principle of Operation ............................................................................................................................ 2

Figure 3 Sensor Assembly Breakaway ................................................................................................................. 3

Figure 4 ITM Circuit Functional Block Diagram ................................................................................................. 4

Figure 5 Sensor Assembly Front View ................................................................................................................ 4

Figure 6 Plug-in Sensor ........................................................................................................................................ 4

Figure 7 Smart Battery Pack ................................................................................................................................ 6

Figure 8 Quad Battery Charger ............................................................................................................................ 6

Figure 9 Tri C Lithium Battery Holder ................................................................................................................ 7

Figure 10 Approval Label .................................................................................................................................... 8

Figure 11 CXT-IR Sensor with Smart Battery Pack Mounting Dimensions...................................................... 11

Figure 12 CXT-IR Sensor with C-Cell Batteries ............................................................................................... 12

Figure 13 Terminal Interconnect for Smart Battery Pack .................................................................................. 14

Figure 14 Magnetic Programming Tool ............................................................................................................. 16

Figure 15 Magnetic Programming Switches ...................................................................................................... 16

Figure 16 Software Flow Chart .......................................................................................................................... 18

Figure 17 Modbus™ Frame Format ................................................................................................................... 27

Figure 18 Battery Orientation Diagram .............................................................................................................. 34

Figure 19 Sensor Cell and ITM Mating ............................................................................................................. 35

List of Tables

Table 1 Gas Factors ............................................................................................................................................ 24

Table 2 Exception Codes .................................................................................................................................... 28

Table 3 CXT-IR Register Map ........................................................................................................................... 29

Table 4 Spare Parts, Sensor Accessories, and Calibration Equipment ............................................................... 42

Table 5 Revision Log ......................................................................................................................................... 43

Model CXT-IR iv

Mailing Address: P.O. Box 8067, The Woodlands Texas 77387-8067

Model CXT-IR

1. Introduction

1.1 Description

Detcon Model CXT-IR combustible gas sensors are no n-intrusive “Smart” sensors designed to
detect and monitor combustible hydrocarbon gases in the air with a detection range of 0-100%
LEL (Lower Explosive Limit). The sensor features an LED display of current reading, fault
and calibration status. A primary feature of the sensor is its method of automatic calibration,
which guides the user through each step via fully scripted instructions illustrated on the LED
display.

The microprocessor-supervised electronics are enclosed in an encapsulated module and housed
in an explosion proof casting.

The unit includes:

• a built in 2.4GHz radio to transmit status wirelessly to a controller,

• a four character alpha/numeric LED to display sensor readings, and

• a menu-driven interface when the hand-held programming magnet is in use.

Non-Dispersive Infrared (NDIR) Optical Sensor Technology

The sensor technology is designed as a miniature plug-in replaceable component, which can easily be changed
out in the field.

The NDIR sensor consists of (Figure 1):

• one infrared lamp source,

• two pyroelectric detectors (active and reference),

• and one optical gas sample chamber.

The lamp source produces infrared radiation, which interacts with the target gas as it is reflected through the
optical gas sample chamber. The infrared radiation contacts each of the two pyroelectric detectors at the
completion of the optical path. The active pyroelectric detector is covered by a filter specific to the part of the
IR spectrum where the target gas absorbs light. The reference pyroelectric detector is covered by a filter
specific to the non-absorbing part of the IR spectrum. When the target gas is present, it absorbs IR radiation
and the signal output from the active detective decreases accordingly. The reference detector output remains
unchanged. The ratio of the active and reference detector outputs are then used to compute the target gas
concentration.

The technique is referred to as non-selective and may be used to monitor most any combustible hydrocarbon
gas. Unlike catalytic bead type sensors, Detcon IR sensors are completely resistant to poisoning from corrosive
gases and can operate in the absence of an oxygen background. The sensors are characteristically stable and
capable of providing reliable performance for periods exceeding 5 years in most industrial environments.

CXT-IR Instruction Manual Rev. 1.6 Page 1 of 44

Model CXT-IR

NOTE

Actual field experience is always the best determination of appropriate calibration intervals.

The CX T-IR sensor will not respond to combustible gases that are not hydrocarbons, such
as H2, NH3, CO, H2S….etc. It can only be used to measure hydrocarbon type gases.

Figure 1 Sensor Cell Construction

Principle of Ope r at io n

The target gas diffuses through a sintered stainless steel flame arrestor and into the volume of the sample gas
optical chamber. An alternating miniature lamp provides a cyclical IR radiation source, which reflects through
the optical gas sample chamber and terminates at the two pyroelectric detectors. The active and reference
pyroelectric detectors each give an output which measures the intensity of the radiation contacting their
surface. The active detector is covered by an optical filter specific to the part of the IR spectrum where the
target gas absorbs light. The reference detector is covered by a filter specific to the non-absorbing part of the
IR spectrum. When present, the target gas absorbs a fraction of the IR radiation and the signal output from the
active detector decreases accordingly. The signal output of the reference detector remains unchanged in the
presence of the target gas. The ratio of the active/reference signal outputs is then used to compute the target
gas concentration. By using the ratio of the active/reference signal outputs, measurement drift caused by the
changes in the intensity of the IR lamp source or changes in the optical path’s reflectivity is prevented (Figure

2).

Figure 2 Principle of Operation

Performance Characteristics

The IR sensor maintains strong sensitivity to most all combustible hydrocarbon gases within the LEL range.
When compared with the typical catalytic bead LEL sensor, the IR sensor exhibits improved long-term zero
and span stability. Typical zero calibration intervals are quarterly to semi-annual and typical span intervals are
semi-annual to annual.

NOTE

The IR sensor generates different signal sensitivity levels for different combustible hydrocarbon target gases.
Unless otherwise specified the CXT-IR sensor will be factory calibrated for methane service. If the target
hydrocarbon gas is other than methane, then the unit will have to be span calibrated and configured in
accordance with this CXT-IR sensor instruction manual.

CXT-IR Instruction Manual Rev. 1.6 Page 2 of 44

Model CXT-IR

100 Series Bottom

Housing Assembly

Plug-in

Replaceable

Sensor Cell

Intelligent Transmitter Module (ITM)
Micro-processor controlled circuit
encapsulated in an Explosion proof
housing.

Magnetic

Programming

Switches

Rain Shield

3

4

" NPT Locking

Nut

Ferrite Bead

All metal components are constructed from electro polished 316 Stainless Steel in order to
maximize corrosion resistance in harsh environments.

Accessory
connections

Wireless

Processor

Intrinsically
Safe Barrier

Plug-In

1.2 Modular Design

The Model CXT-IR Sensor Assembly is completely modular and is made up of four parts (Figure 3)

1) CXT-IR Intelligent Transmitter Modu le (I TM)

2) Plug-in infrared Sensor

3) CXT Series Bottom Housing

4) Splash Guard

Figure 3 Sensor Assembly Breakaway

NOTE

1.2.1 CXT-IR Intelligent Transmitter Module

The Intelligent Transmitter Module (ITM) is a fully encapsulated microprocessor-based package that accepts a
plug-in field replaceable combustible gas sensor.

Circuit funct ion s in c lude (Figure 4):

• extensive I/O circuit protection,

• sensor pre-amplifier,

• on-board power supplies,

• microprocessor,

• LED display,

• magnetic programming switches,

• built-in 2.4GHz radio

Magnetic program switches located on either side of the LED Display are activated by a hand-he ld magnetic
programming tool, allowing a non-intrusive operator interface with the ITM. The program switches allows
calibration without declassifying the area.

CXT-IR Instruction Manual Rev. 1.6 Page 3 of 44

Micro-

I/O

Model CXT-IR

Program Switch #1

LED Display

Program Switch #2

Housing Bottom
Locking Set-Screw

detcon inc.

LEL Sensor

detcon inc.

MODEL

CXT- IR

Detconꞌs combustible sensors have a long shelf life and are supported by an industry­leading warranty.

Figure 4 ITM Circuit Functional Block Diagram

Figure 5 Sensor Assembly Front View

1.2.2 Field Replaceable Sensor

Detconꞌs infrared gas sensors are field proven, plug-in sensors with over-sized gold-plated connections that
eliminate corrosion problems. The sensor can be accessed and replaced in the field easily by releasing the
locking screw and unthreading the splashg uard ad ap ter assem bly .

NOTE

Figure 6 Plug-in Sens or

1.3 CXT Wireless Network

CXT-IR Instruction Manual Rev. 1.6 Page 4 of 44

Model CXT-IR

If there are multiple CXT-IR networks in the same vicinity, each system must reside on a
different RF Channel to keep data from one appearing on the other system.

The CX T-IR sensor utilizes a transceiver radio, based on the IEEE 802.15.4 standard. The transceiver operates
at 2.4 GHz using DSSS encoding for robustness in noisy conditions and to resist jamming. DSSS transmits
data across a wider frequency range than the actual frequency range required for the information. This
operation minimizes cross tal k and interference from other transceivers and is less susceptible to noise from
other sources.

The IEEE 802.15.4 defines 16 separate RF Channels that can be used in the 2.4 GHz range. The default
channel is 1 but can be changed if there is RF interference or if there is an existing network using that channel.
Transceivers will only respond to other transceivers with the same RF Channel.

NOTE

The 802.15.4 standard also implements a mesh network allowing any CXT-IR transceiver to relay or repeat
data between adjacent neighbors. This makes the network very robust and provides the following immediate
benefits.

• Allows re-routing of data in case of loss of a transceiver

• Allows re-routing around wireless obstacles

• Longer distances between transceivers because data can “hop” from one transceiver to the next

• Included in sensor, controller and alarm station transceivers

• CXT-IR transceivers can be deployed with less concern about physical location

1.4 Battery Pack Options

The CX T-IR can be powered by a battery pack that enables the IR to be remotely mounted without the need
for external cabling. Detcon offers several battery pack options that are factory installed. Contact Detcon for
more information on these options.

1.4.1 Detconꞌs Smart Battery Pack

The Detcon’s plug-in Smart Battery Pack provides an output of 12VDC (See Figure 7). The CXT-IR monitors
the battery pack for remaining battery life. The battery pack consists of rechargeable Lithium-Ion batteries
and is equipped with integrated safety electronics that include fuel gauge, voltage, current and temperature
monitoring circuits. This “smart” circuitry continuously monitors the battery’s condition and reports critical
status information to the wireless transceiver via the Modbus™ registers. The battery pack is designed to plug
onto an 8-pin Beau connector on a Terminal Board that the sensor is connected to. The battery Pack and
Terminal Board are housed in the Detcon Aluminum Condulet to protect them from exposure to outside
elements and still provide Class I Div 1, C, and D approvals. Operating periods before recharge will vary
based on sensor attached, but can be as long as 5-6 months and battery life can be up to 5 years before battery
pack replacement is required. Improper use of the battery pack may be hazardous to personnel or the
environment and will void the warranty.

CXT-IR Instruction Manual Rev. 1.6 Page 5 of 44

Model CXT-IR

Figure 7 Smart Battery Pack

Quad Battery Charger (Optional)

Detcon’s Smart Battery Pack can be charged as needed using Detcon’s optional Quad Battery Charger which
can charge up to four battery packs at one time. The Quad Battery Charger comes with a plug-in AC/DC
adapter that plugs into a standard 100-240VAC outlet for power. The DC end of the adapter plugs into the DC
power jack of the charger providing 24VDC. The Quad Battery Charger has four charging ports, each with 8­pin Beau connectors for battery pack connection. The ports and connectors are keyed to prevent incorrect
positioning and connection. Each port has its own “FAULT” LED indicator and “CHARGE” LED indicator
and will display either a red light or green light depending on the status of each battery being charged.
Charging times will vary depending on the charge state of each battery pack, but a full charge of a depleted
battery pack can take up to 24 hours.

Figure 8 Quad Battery Charger

1.4.2 Tri-C Lithium Battery Pack

The Tri-C Lithium Battery Pack (Figure 9) c on tai n s thr ee 3 .6V Li thi um P ri mar y C s i ze ba tt er ies whi c h are not
re-chargeable. This battery pack offers a more compact size, and provides the unit with 10.8 volts. The
batteries are contained in a battery holder mounted in Detconꞌs stainless steel explosion proof mini-condulet.

CXT-IR Instruction Manual Rev. 1.6 Page 6 of 44

Model CXT-IR
This option offers a smaller foot print, but provides less run time than Detcon’s Smart Battery Pack. The CXT-

IR sensors will operate up to 60 days before battery replacement is needed. The addition of Detconꞌs Stainless

Steel Mini Condulet provides Class I Div 1, Group B, C, and D ratings.

Figure 9 Tri C Lithium Battery Holder

CXT-IR Instruction Manual Rev. 1.6 Page 7 of 44

Model CXT-IR

2. Installation

2.1 Hazardous Location s Installation Guidelines for Safe Use

1. Install the sensor only in areas with classifications matching the approval label. Follow all warnings

listed on the label.

Figure 10 Approval Label

2. Do not remove the junction box cover while in the classified are unless it is conformed the there is no

explosive gas levels in the area.

3. A good ground connection should be verified between the sensor’s metal enclosure and the junction

box. If a good ground connection is not made, the sensor can be grounded to the junction box using
the sensor’s external ground lug. Verify a good ground connection between the junction box and earth
ground.

4. Proper precautions should be taken during installing and maintenance to avoid the build-up of static

charge on the plastic components of the sensor (Rain Shield an d Antenna Dome Co ver) Wipe with
damp cloth on plastic components to avoid static discharge.

5. Do not substitute components. Substitution of components may impair the intrinsic safety rating.

6. Do not operate the sensor outside of the stated operating temperature limits.

7. Do not operate the sensor outside the stated operating limits for voltage supply.

8. These sensors meet ATEX standards EN60079-0:2012. EN60079-1:2007 and EN60079-11:2012.

9. These sensors have a maximum safe location voltage of UM=30V.

10. These sensors pass dielectric strength of 500VRMS between circuit and enclosure for a minimum of 1

minute at a maximum test current of 5mA.

11. The CXT-IR mus t only use combustible sensing cell model 371-IR1II1-000.

12. Th e CXT -IR is only to be used with Detcon P/N 360-026500-000 batteries (Tadiran Model TL-5920).

The battery holder utilizes three of these batteries in series to operate the sensor.

WARNING:

CSA certification does not i nc lude wireless communication or Modbus used for combustible gas
performance.the wire less communication or M odbus may only be used for dat a collection or
record keeping with regard to combustible gas detection. Gas indication and alarm fnctions for
performance are only permitted locally by the detector.

CXT-IR Instruction Manual Rev. 1.6 Page 8 of 44

Model CXT-IR

In all installations the gas sensor should point straight down (Figure 11). Improper sensor
orientation may result in false readings and permanent sensor damage.

2.2 Sensor Placement

Selection of sensor location is critical to the overall safe performance of the product. Six factors play an
important role in selection of sensor locations:

• Density of the gas to be detected

• Most probable leak sources within the industrial process

• Ventilation or prevailing wind conditions

• Personnel exposure

• Placement of transmitting antenna

• Maintenance access

Density

Placement of sensors relative to the density of the target gas should be located within 4 feet of grade as heavy
gases tend to settle in low lying areas. For gases lighter than air, sensor placement should be 4 to 8 feet above
grade in open areas or in pitched areas of enclosed spaces.

Leak Sources

The most probable leak sources within an industrial process include flanges, valves, and tubing connections of
the sealed type where seals may either fail or wear. Other leak sources are best determined by facility
engineers with experience in similar processes.

Ventilation

Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a manner
where the migration of gas clouds is quickly detected.

Personnel Exposure

The undetected migration of gas clouds should not be allowed to approach concentrated personnel areas such
as control rooms, maintenance or warehouse buildings. A more general and applicable sensor location is
combining leak source and perimeter protection in the best possible configuration.

Maintenance Access

Consideration should be given to providing easy access for maintenance personnel and the consequences of
close proximity to contaminants that may foul the sensor prematurely.

NOTE

Placement of RF Antenna

Placement of the sensor should have consideration made for line of sight RF transmissions. The dev ices shou ld
be placed in a reasonable proximity to other devices in the network. Obstacles between CXT transceivers can
impact RF line-of-sight and may result in communication problems. The CXT sensor should be in view of at
least one other transceiver.

Additional Placement Considerations

CXT-IR Instruction Manual Rev. 1.6 Page 9 of 44

Model CXT-IR

If wall mounting without a mounting plate, ensure to use at least 0.5"spacers under the

from the wall and allow access clearance to the sensor assembly.

The sensor should not be positioned where it may be sprayed or coated with surface contaminating substances.
Painting sensor assemblies is prohi bi ted.

Although the sensor is designed to be RFI resistant, it should not be mounted in close proximity to high­powered radio transmitters or similar RFI generating equipment.

When possible mount in an area void of high wind, accumulating dust, rain, or splashing from hose spray,
direct steam releases, and continuous vibration. If the sensor cannot be mounted away from these conditions
then make sure the Detcon Harsh Location Dust Guard accessory is used.

Do not mount in locations where temperatures will exceed the operating temperature limits of the sensor.
Where direct sunlight leads to exceeding the high temperature-operating limit, use a sunshade to help reduce
temperature.

2.3 Sensor Cont aminants and Interferenc e

Detcon CXT-IR combustible hydrocarbon gas sensors may be adversely affected by exposure to certain
airborne substances. Loss of sensitivity or corrosion may be gradual if such materials are present in sufficient
concentrations.

The performance of the IR sensor may be impaired during operation in the presence of substances that can
cause corrosion on gold plating. Other inhibiting substances are those that can coat the internal walls of the
optical chamber and reduce reflectivity. These include but are not limited to heavy oil deposits, dust/powder,
water condensation, and salt formation. Continuous and high concentrations of corrosive gases (such as Cl
H

S, HCl …etc.) may also have a detrimental long-term effect on the sensorꞌs service life.

2

The presence of such substances in an area does not preclude the use of this sensor technology, although it is
likely that the sensor lifetime will be shorter as a result. Use of this sensor in these environments may require
more frequent calibration checks to ensure safe system performance.

For the CXT -IR combustible gas sensors there are no known cross-interference gases that are not combustible
hydrocarbon gases.

2

,

2.4 Sensor Mounting

The CXT-IR should be vertically oriented so that the sensor points straight downward (Figure 11). The
explosion-proof enclosure or junction box is typically mounted on a wall or pole. Detcon provides a selection
of standard junction boxes in both Aluminum and Stainless Steel.

NOTE

When mounting on a pole, secure the Junction Box to a suitable mounting plate and attach the mounting plate
to the pole using U-Bolts. (Pole-Mounting brackets for Detcon Junction Boxes are available separately.)

CXT-IR Instruction Manual Rev. 1.6 Page 10 of 44

Detcon Aluminum Junction Box’s 1/4" mounting holes to move the sensor assembly away

Model CXT-IR

8-32 tapped
ground point

7.45"

3

4

NPT Port

9.5"

Wall

(or other

mounting surface)

Splash Guard Adapter

Splash Guard

ITM Assembly

23" Typ.

Use spacers to move

sensor assembly away

from wall at least 0.5".

Spacer

1

4

" mounting

holes

Spacer

5.5"

Figure 11 CXT-IR Sensor with Smart Battery Pack Mounting Dimensions

CXT-IR Instruction Manual Rev. 1.6 Page 11 of 44

Model CXT-IR

6-32 tapped
ground point

4.1"

3

4

NPT Port

3.64"

Ø0.4 X 0.475"
mounting
holes

Splash Guard Adapter

Splash Guard

ITM Assembly

3.45"

22"Typ.

Mini Condulet with
Battery Holder and
Batteries

2.5 Electrical Installation

Figure 12 CXT-IR Sensor wi th C-Cell Batteries

The CXT is designed to be battery operated, and normally will not have external cabling or wiring. If the
sensor requires external wiring, the sensor assembly should be installed in accordance with local electrical
codes. Proper electrical installation of the gas sensor is critical for conformance to electrical codes and to avoid
damage due to water leakage.

CXT-IR Instruction Manual Rev. 1.6 Page 12 of 44

Model CXT-IR

A conduit seal is typically required to be located within 18" of the J-Box and Sensor
Assembly. Crouse Hinds type EYS2, EYD2 or equivalent are suitable for this purpose.

The Detcon Warranty does not cover water damage resulting from water leaking into the
enclosure.

Any unused ports should be blocked with suitable 3/4" male NPT plugs. Detcon supplies

use an appropriate male plug of like construction material.

A 24V solar panel is the most common option for supplying external power. A

the C-cells. A 24V input with the C-cells will damage the cells.

The safety approvals require removing entire sensor assembly to a non-hazardous area
before changing out the batteries or battery pack.

If a conduit run exists, a drain should be incorporated. The drain allows H2O condensation inside the conduit
run to safely drain away from the sensor assembly. The electrical seal fitting is required to meet the National
Electrical Code per NEC Article 500-3d (or Canadian Electrical Code Handbook Part 1 Section 18-154).
Requirements for locations of electrical seals are covered under NEC Article 501-5. Electrical seals also act as
a secondary seal to prevent water from entering the wiring terminal enclosure. However, they are not designed
to provide an absolute watertight seal, especially when used in the vertical orientation.

NOTE

NOTE

NOTE

one 3/4" NPT male plug with each J-box enclosure. If connections are other than 3/4" NPT,

If the Detcon CXT-IR was ordered with battery packs, no wiring is necessary. Although an external 24V
source can be applied in some instances. If an external power source is incorporated, wire the external power
source to the Terminal Interconnect board as prescribed in Figure 13.

Do not apply System power to the sensor until all wiring is properly terminated

CAUTION

(2.6 Initial Start Up).

2.5.1 Applying Power to the Unit

CAUTION

1. Remove the junction box cover.

2. If external power is to be applied to the unit, connect incoming 24V to the terminal labeled "+" and 24V

Return to the terminal labeled "-".

3. Install the batteries.

solar panel will recharge the Detcon Smart Battery Pack. It CANNOT be used with

NOTE

a) For units utilizing the 12V Smart Battery Pack (Figure 13), plug the battery pack into the terminal

board. If the sensor has a power switch, power will not be applied until the switch is turned on. If
the unit does not have a power switch, power will be applied, and the unit will proceed to power
up (Section 2.6).

b) If the unit utilizes the C sized lithium 3.6V batteries and battery holder, install the batteries

properly. If the sensor has a power switch, power will not be applied until the switch is turned on.
If the unit does not have a power switch, power will be applied, and the unit will proceed to power
up (Section2.6).

CXT-IR Instruction Manual Rev. 1.6 Page 13 of 44

Model CXT-IR

Black

Wht/Blk

Wht/Brn

Red

To Sensor

24V Power

To External

Return

24VDC

+

-

A 6-32 or 8-32 threaded exterior ground point is provided on most junction boxes for an

xternal ground. If the Sensor Assembly is not mechanically grounded, an external ground

strap must be used to ensure that the sensor is electrically grounded.

In normal operation the display will come on once every 10 seconds, will display the
current reading for about 2 seconds, and will return to a blank display to conserve battery
power.

4. Replace the junction box cover after Initial Start Up.

Figure 13 Terminal Interconnect for Smart Battery Pack

NOTE

e

2.6 Initial Start Up

2.6.1 Combustible Gas Sensors

Upon completion of all mechanical mounting and installation of the batteries power is now applied to the unit.
If the unit is equipped with the optional power switch, power is applied by pushing the switch. Observe the
following normal conditions:

1. Upon power up, the sensor will scroll CXT-IR and will then display the current reading for approximately

5 seconds. A temporary upscale reading may occur as the sensor stabilizes. This upscale reading will
decrease to 0% LEL within 1 to 2 minutes of power-up, assuming there is no gas in the area of the sensor.

2. After the initial power up, the sensor display will turn off. Thereafter the display will come on once every

10 seconds and will display the current reading for about 2 seconds, and will return to a blank display to
conserve battery power.

NOTE

CXT-IR Instruction Manual Rev. 1.6 Page 14 of 44

Model CXT-IR

Calibration gas generators using perm tubes or electrochemical sources may be used in
place of span gas cylinders.

Wind Guard must be used when calibrating with the integral cal port to ensure proper
calibration.

Initial Operational Tests

After a warm up period of 1 hour (or when zero has stabilized), the sensor should be checked to verify
sensitivity to the target gas.

Material Requirements

• Detcon PN 613-120000-700 700 Series Splash Guard with integral Cal Port and Calibration Wind

Guard (P/N 943-000000-000) -OR-

• Detcon PN 943-000006-132 Threaded Calibration Adapter - OR -

• Detcon P/N 943-01747-T05 Teflon Calibration Adapter for highly reactive gases

• Detcon Span Gas; 50% of range target gas in balance N

or Air at fixed flow rate between 200-

2

500cc/min

NOTE

NOTE

1. Attach the calibration adapter to the Splashguard Adapter Assembly or connect tubing to integral cal

port. It is recommended that the Wind Guard (Detcon PN 943-000000-000) is installed over the Splash
Guard during calibration.

2. Apply the test gas at a controlled flow rate of 200 - 500cc/min (500cc/min is the recommended flow).

Observe that the ITM display increases to a level near that of the applied calibration gas value.

3. Remove test gas and observe that the display decreases to 0.

4. If a calibration adapter was used during these tests, remove it from the unit, and re-install the Splash

Guard.

5. If the wind guard was used, remove the wind guard.

Initial operational tests are complete.

CXT-IR Combustible gas sensors are factory calibrated prior to shipment, and should not require significant
adjustment on start up. However, it is recommended that a complete calibration test and adjustment be
performed 16 to 24 hours after power-up. Refer to calibration instructions in Section 3.3.

CXT-IR Instruction Manual Rev. 1.6 Page 15 of 44

Model CXT-IR

detcon inc.

MODEL

CXT-IR

Programming Switch #1

LED Display

Programming Switch #2

While in the program mode, if there is no magnetic switch interaction after 4 consecutive
menu scrolls, the sensor will automatically revert to normal operating condition. While

remain active.

3. Operation

The Operator Interface of the Model CXT Series gas sensors is accomplished via two internal magnetic
switches located to either side of the LED display (Figure 15). The two switches, labeled PGM1 and PGM2,
allow for complete calibration and configuration, eliminating the need for area de-classification or the use of
hot permits.

Figure 14 Magnetic Programming Tool

The magnetic programming tool (Figure 14) is used to operate the magnetic switches. Switch action is defined
as momentary contact (a swipe), a 3 second hold, and a 10 second hold. (Hold times are defined as the time
from the point when the arrow prompt appears. Swiping the magnet does not display the prompt.) For
momentary contact use, the programming magnet is briefly held over a switch location, or swiped. For 3
second hold, the programming magnet is held in place over the switch location for three seconds. For 10
second hold, the programming magnet is held in place over the switch location for 10 seconds. The 3 and 10
second holds are generally used to enter calibration/program menus and save new data. The momentary
contact is generally used to move between menu items and to modify set-poi nt values. Arrows (◄ and ►) a re
used on the LED display to indicate when the magnetic switches are activated. The location of PGM1 and

PGM2 are shown in Figure 15.

Figure 15 Magnetic Programming Switches

NOTE

changing values inside menu items, if there is no magnet activity after 3 to 4 seconds the
sensor will revert to the menu scroll. If the sensor is in Bump Test mode, the display will

CXT-IR Instruction Manual Rev. 1.6 Page 16 of 44

Model CXT-IR

3.1 Operator Interface

The operating interface is menu-driven by the two magnetic program switches located under the target marks
of the sensor housing. The two switches are referred to as PGM1 and PGM2. The menu list consists of three
menu items that include sub-menus; normal operation, calibration mode and, program mode.

Normal Operation

Concentration Reading is displayed once every 10 seconds.

Calibration Mode

AutoZero
AutoSpan

Program Mode

View Sensor Status

Mp App ##.##
CP App ##.##
Rf App ##.##.##
RfSw ##.##
Modbus™ ID ##
Serial Number ##.##.##
RF Channel ##
Network ID ####
Sensor Sn ########
Range ###
Autospan Level ##
Last Cal ## Days
Sensor Life ###%
Temperature ##C

Set Gas Type
Set Autospan Level
Set Gas Factor
Bump Test
Restore Defaults
Set RF Channel
Set Modbus™ ID

CXT-IR Instruction Manual Rev. 1.6 Page 17 of 44

Model CXT-IR

dec

LEGEND:

PGM1 - Program Switch Location #1

PGM2 - Program Switch Location #2

(S) - Momentary Swipe

(M) - Momentary hold of Magnet during text

scroll until the ">" appears, then release

(3) - 3 second hold from ">" prompt

(10) - 10 second hold from ">" prompt

Auto Time-out - 5 seconds

inc - Increase

dec - Decrease

#, ##, ### - numeric values

Serial N. ##.##.##

Temperature ##C

RF Channel ##

AutoZero

PGM1 (3)

PGM2 (10)

PGM2 (3)

RF App ##.##.##

CP App ##.##

RF SW ##.##

Modbus ID ####

inc

Auto Time-Out

View Sensor Status

PGM1/2 (3)

PGM1/2 (M)

MP App ##.##

PGM2 (S)

PGM1/2 (3)

PGM1 (S)

##

AutoTime-out

PGM1/2 (3)

PGM1/2 (M)

AutoSpan

Normal Operation

PGM1 (3)

Auto Time-OutAuto Time-Out

inc

PGM2 (S)

PGM1/2 (3)

PGM1 (S)

Type XX

PGM1/2 (3)

PGM1/2 (M)

dec

PGM1/2 (3)

PGM1/2 (M)

Set Gas Factor

PGM1/2 (M)

Defaults Restored

PGM1/2 (3)

Restore Defaults

Auto Time-Out

dec

inc

PGM2 (S)

PGM1/2 (3)

PGM1 (S)

##

AutoTime-out

PGM1/2 (3)

PGM1/2 (M)

Set RF Channel

Auto Time-Out

inc

PGM2 (S)

PGM1/2 (3)

PGM1 (S)

##

PGM1/2 (3)

PGM1/2 (M)

Set Modbus ID

dec

Set Autospan Level

Network ID ##

Range ###

Last Cal ## Days

Sensor Life ###%

Set Gas Type

Auto Time-Out

PGM1/2 (3)

Bump Test Started

PGM1/2 (3)

PGM1/2 (M)

Bump Test

2 minute timeout

PGM2 (S)

PGM1/2 (3)

PGM1 (S)

##

inc

dec

3.1.1 Software Flowchart

Figure 16 Software Flow Chart

CXT-IR Instruction Manual Rev. 1.6 Page 18 of 44

Model CXT-IR

The zero gas source may be zero air or N2 if local ambient air contains target or interference
gases.

The Calibration Wind Guard must be used when the Splashguard Adapter with integral Cal

on Wind Guard may result in an inaccurate

AutoZero calibration.

3.2 Normal Operation

In normal operation, the ITM Display will be blank and will display the gas reading once every 10 seconds for
about 2 seconds (normally appear as 0). At any time swiping a magnet across either PGM1 or PGM2 will
cause the ITM to display the units and gas type (i.e. % LEL or PPM H2S). If the sensor is actively
experiencing any diagnostic faults, a swipe of the magnet will cause the display to scroll the fault condition.
Refer to Section 3.5for more information on fault conditions.

3.3 Calibration Mode

Zero and span calibration should be performed on a routine basis (quarterly minimum is advised) to ensure
reliable performance. If a sensor has been exposed to any de-sensitizing gases, or to very high over-range
combustible gas levels, re-calibration should be considered. Unless otherwise specified, span adjustment is
recommended at 50% of the full scale range.

To enter Calibration Mode hold the magnet over PGM1 for 3 seconds. If the sensor is experiencing a fault
condition the "◄" prompt will not appear until the fault(s) have been displayed. When the ITM enters
Calibration Mode the display will scroll Pgm1=Zero . . . Pgm2=Span twice before returning to Normal Mode
(about 5 seconds).

3.3.1 AutoZero

The AutoZero function is used to zero the sensor. AutoZero should be performed periodically or as required.
AutoZero should be considered after periods of over-range target gas exposure. Local ambient air can be used
to zero calibrate a combustible gas sensor as long as it can be confirmed that it contains no target or
interference gasses. If this cannot be confirmed then a zero air or N

Material Requirements:

• DetconMicroSafe™ Programming Magnet (PN 327-000000-000)

• Detcon Splash Guard with integral Cal Port (PN 613-120000-700) and Calibration Wind Guard (PN

613-120000-700) -OR-

• Detcon Threaded Calibration Adapter (PN 943-000006-132)

• Detcon Zero Air cal gas (PN 942-001123-000) (or use ambient air if no target gas is present)

• Detcon Nitrogen 99.99% (PN 942-640023-100)

cylinder should be used.

2

NOTE

NOTE

Port is used. Failure to use the Calibrati

a) For combustible gas sensors, if the ambient air is known to contain no target gas content, then it can be

used for zero calibration. If a zero gas cal cylinder is going to be used, attach the calibration adapter and
set flow rate of 200-500cc/min (500cc/min is the recommended flow rate) and let sensor purge for 1 to 2
minutes before executing the AutoZero.

b) From normal operation, enter calibration mode by holding the programming magnet over PGM1 for 3

seconds The display will then scroll Pgm1=Zero Pgm2=Span. Hold the programming magnet over
PGM1 for 3 seconds once the "◄" prompt appears to execute AutoZero (or allow t o timeout i n 5 seconds
if AutoZero is not desired).

CXT-IR Instruction Manual Rev. 1.6 Page 19 of 44

Model CXT-IR

The "◄" prompt will show that the magnetic switch is activated during the 3 second hold
period.

Upon entering calibration mode, the Modbus™ status register bit 14 is set to signify the

operation.

Before performing AutoSpan calibration, verify that the AutoSpan level matches the span
calibration gas concentration as described in Section3.4.3 Set AutoSpan level.

NOTE 1

Contact Detcon for ordering information on span gas cylinders.

A target gas concentration of 50% of range is strongly recommended. This should be
supplied at a controlled flow rate of 200 to 500cc/min, with 500cc/min being the

levels of 5% to 100% of range.

The Calibration Wind Guard must be used when the Splashguard Adapter with integral Cal
Port is used. Failure to use the Calibration Wind Guard may result in an inaccurate
AutoZero calibration.

It is generally not advised to use other gasses to cross-calibrate for span. Cross-calibration
by use of other gasses should be confirmed by Detcon.

Verification that the calibration gas level setting matches the calibration span gas

numbers must be equal.

NOTE

NOTE

sensor is in-calibration mode. This bit will remain set until the program returns to normal

c) The ITM will display the following sequence of text messages as it proceeds through the AutoZero

sequence:

Zero Cal . . . Setting Zero . . . Zero Saved (each will scroll twice)

d) Remove the zero gas and calibration adapter, if applicable.

3.3.2 AutoSpan

The AutoSpan function is used to span calibrate the sensor. AutoSpan should be performed periodically or as
required. AutoSpan should be considered after periods of over-range target gas exposure. Unless otherwise
specified, span adjustment is recommended at 50% of range. This function is called AUTO SPAN.

NOTE

Material Requirements:

• DetconMicroSafe™ Programming Magnet (PN 327-000000-000)

• Detcon Splash Guard with integral Cal Port (PN 613-120000-700) and Calibration Wind Guard (PN

613-120000-700) -OR-
Detcon Threaded Calibration Adapter (PN 943-000006-132)

• Detcon Span Gas. Recommended span gas is 50% of range with target gas. Other suitable span gas

sources containing the target gas in air or N2 balance are acceptable .

NOTE 2

recommended flow rate. Other concentrations can be used if they fall within allowable

NOTE 3

NOTE 4

concentration is required before executing AutoSpan calibration. These two

CAUTION

AutoSpan consists of entering calibration mode and following the menu-displayed instructions. The display
will ask for the application of span gas in a specific concentration. The applied gas concentration must be
equal to the calibration gas level setting. The factory default setting and recommendation for span gas

CXT-IR Instruction Manual Rev. 1.6 Page 20 of 44

Model CXT-IR

The "◄"prompt will show that the magnetic switch is activated during the 3 second hold
period.

Upon entering calibration mode, the Modbus™ status register bit 14 is set to signify the

operation.

If the sensor fails the minimum signal change criteria, a Range Fault will be declared and
the Range Fault bit will be set on the Modbus™ output.

If the sensor fails the clearing time criteria, a Clearing Fault will be declared and the
Clearing fault bit will be set on the Modbus™ output.

concentration is 50% of range. If a span gas containing the recommended concentration is not available, other
concentrations may be used as long as they fall between 5% and 95% of range. However, any alternate span
gas concentration value must be programmed via the Set AutoSpan Level menu before proceeding with
AutoSpan calibration. Follow the instructions a) through f) below for AutoSpan calibration.

a) Verify that the AutoSpan level is equal to the calibration span gas concentration. (Refer to View Sensor

Status in Section 3.4.1.) If the AutoSpan level is not equal to the calibration span gas concentration, adjust
the AutoSpan lev el a s instructed in Sec tio n 3.3.2AutoSpan.

b) From normal operation, enter calibration mode by holding the programming magnet over PGM1 for 3

seconds.

NOTE

c) The display will then scroll PGM1=Zero PGM2=Span. Hold the programming magne t o ve r PGM2 for

3 seconds to execute AutoSpan (or allow to timeout in 5 seconds if AutoSpan is not intended). The ITM
will then scroll Apply XX % Gas.

NOTE

sensor is in-calibration mode. This bit will remain set until the program returns to normal

d) Apply the span calibration test gas for combustible gas sensors at a flow rate of 200-500cc/min (500cc/min

is the recommended flow rate). As the sensor signal begins to increase the display will switch to flashing
XX reading as the ITM shows the sensorꞌs as f ound response to the span gas presented. If it fails to meet
the minimum in-range signal change criteria within 2 minutes, the display will report Range Fault twice
and the ITM will return to normal operation, aborting the AutoSpan sequence. The ITM will continue to
report a Range Fault until a successful calibration is completed.

Assuming acceptable sensor signal change, after 1 minute the reading will auto-adjust to the programmed
AutoSpan level. The ITM then reports the follow ing messag es : Remove Gas.

e) Remove the span gas source and calibration adapter. The ITM will report a live reading as it clears toward

0. When the reading clears below 10% of range, the ITM will display Span Complete and will revert to
normal operation. If the sensor fails to clear to less than 10% in less than 5 minutes, a Clearing Fault will
be reported twice and the ITM will return to normal operation, aborting the AutoSpan sequence. The ITM
will continue to report a Clearing Fault until a successful calibration is completed.

f) AutoSpan calib ration is com ple te.

NOTE

NOTE

CXT-IR Instruction Manual Rev. 1.6 Page 21 of 44

Model CXT-IR

The arrow prompt (◄ and ►) will s how t ha t the magnetic switch is activated during the 10
second hold period.

PGM1 moves the menu items from right to left and PGM2 moves the menu items from left
to right.

3.4 Program Mode

Program Mode provides a View Sensor Status menu to check operational and configuration parameters.
Program Mode also provides for adjustment of the AutoSpan Level, Gas Factor, Gas Type and Range, and
Serial ID.

The Program Mode menu items appear in the order presented below:
View Sensor Status
Set Gas Type
Set AutoSpan Level
Set Gas Factor
Bump Test
Restore Defaults
Set RF Channel
Set Modbus™ ID

Navigating Program Mode
From normal operation, enter program mode by holding the magnet over PGM2 for 10 seconds.

NOTE

The ITM will enter program mode and the display will scroll the first menu item View Sensor Status. To
advance to the next menu item, hold the magnet over PGM1 or PGM2 while the current menu item text is
scrolling. At the conclusion of the text scroll the arrow prompt for PGM2 or PGM1 will appear, and
immediately remove the magnet. The ITM will advance to the next menu item. Repeat this process until the
desired menu item is displayed.

NOTE

To enter a menu item, hold the magnet over PGM1 or PGM2 while the menu item is scrolling. At the
conclusion of the text scroll the arrow prompt for PGM2 or PGM1 will appear, continue to hold the magnet
over PGM1 or PGM2 for an additional 3 to 4 seconds to enter the selected menu item. If there is no magnet
activity while the menu item text is scrolling (typically 4 repeated text scrolls), the ITM will automatically
revert to normal operation.

3.4.1 View Sensor Status

View Sensor Status displays all current configuration and operational parameters including:

• sensor type,

• software version number,

• detection range,

• AutoSpan level,

• days since last AutoSpan,

• estimated remaining sensor life,

• gas factor,

• gas type,

• and sensor ambient temperature.

CXT-IR Instruction Manual Rev. 1.6 Page 22 of 44

Model CXT-IR

NOTE

The default value for Gas Type is methane (%LEL).

From the View Sensor Status text scroll, hold the magnet over PGM1 or PGM2 until the arrow prompt
appears and continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to
scroll Status Is). The display will scroll the complete list of sensor status parameters sequentially.

When the status list sequence is complete, the ITM will revert to the View Sensor Status text scroll.
The user can either:

a) review list again by executing another 3 to 4 second hold,
b) move to another menu item by executing a momentary hold over PGM1 or PGM2, or
c) return to normal operation via automatic timeout of about 15 seconds (the display will scroll View

Sensor Status four times and then return to normal operation).

3.4.2 Set Gas Type

The IR sensor has a slightly different linearization requirement for different groupings of target gases.
The two selections are:

• %LEL and

• %VOL.

The Set Gas Type menu function is a simple choice between these two gas type groupings.

The menu item appears as: Set Gas Type.

From the Set Gas Type and Range text scroll, hold the magnet over PGM1 or PGM2 until the arrow prompt
appears and continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to
scroll %LEL / %VOL). Swipe the magnet momentarily over PGM2 or PGM1 to change the selection until
the correct choice is displayed. Hold the magnet over PGM1 or PGM2 for 3 seconds to accept the new value.
The display will scroll Type Saved, then Set R ange followed by the currently selected Range. Momentarily
hold the magnet over PGM1 or PGM2 to change the Range Selection until the correct value is displayed.
Hold the magnet over PGM2 for 3 seconds to accept the new value.

Move to another menu item by executing a momentary hold, or, return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Set Gas Type 4 times and then return to normal
operation).

3.4.3 Set AutoSpan Level

Set AutoSpan Level is used to set the span gas concentration level that is being used to calibrate the sensor.
This level is adjustable from 5% to 95% of range. The current setting can be viewed in View Program Status.

The menu item appears as: Set AutoSpan Level.

From the Set AutoSpan Level text scroll, hold the magnet over PGM1 or PGM2 until the arrow prompt
appears and continue to hold the magnet in place for an additional 3-4 seconds (until the display starts to scroll
Set Level). The displ ay wi ll s wit ch t o XX (where XX is the current gas level). Swipe the magnet momentarily
over PGM2 to increase or PGM1 to decrease the AutoSpan Level until the correct level is displayed. When
the correct level is achieved, hold the magnet over PGM2 f or 3 to 4 seconds to accept the new value. The
display will scroll Level Saved, and revert to Set AutoSpan Level text scroll.

Move to another menu item by executing a momentary hold, or return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Set AutoSpan Level 4 times and then return to normal
operation).

CXT-IR Instruction Manual Rev. 1.6 Page 23 of 44

Model CXT-IR

The default value for Gas Factor is 1.0. This would be used when the target gas is the same
as the cal gas.

Gas

Factor

Gas

Factor

Gas

Factor

Acetic Acid

2.00

Decane

1.53

Naphthalene

Acetone

1.21

Ethyl Alcohol

0.35

n-Nonane

1.53

Benzene

1.00

Ethane

0.38

n-Octane

1.34

1,3-Butadiene

1.80

Ethyl Benze ne

1.07

n-Pentane

0.77

Butane

0.77

Ethylene

2.39

Propane

0.63

Iso-Butane

0.72

n-Heptane

0.98

iso-Propyl Alcohol

0.54

Butene-1

0.67

n-Hexane

1.00

Propylene

0.80

n-Butyl Alcohol

0.63

Dimethyl Et her

0.40

Toluene

1.00

iso-Butyl Alcohol

0.63

Methane

1.00

Vinyl Acetate

1.43

Cyclohexane

0.89

Methanol

0.41

Vinyl Chloride

Cyclopropane

0.45

Methyl Ethyl Ketone

0.77

Xylene

1.00

3.4.4 Set Gas Factor

Because of the CXT-IR sensorꞌs almost universal response to combustible hydrocarbon gases, the CXT-IR
sensor can be configured and calibrated to detect a variety of combustible gases. The detected gas is referred to
as the "target gas" and the span calibration gas is referred to as the "cal gas". In cases where the cal gas is
different from the target gas, the Set Gas Factor menu function is used to maintain accuracy. This feature
allows for a significant degree of flexibility in the detection and span calibration process.

NOTE

Set Gas Factor is used to make the appropriate signal sensitivity adjustment when the target gas is different
from the cal gas. This is necessary because the IR sensor has different signal strengths for each combustible
hydrocarbon gas. The Gas Factor value is adjustable from 0.2 to 5.0. It represents the translation between the
target gas and the cal gas when they are different.

The menu item appears as: Set Gas Factor.

To calculate the correct Gas Factor (Table 1), take the Gas Factor of the target gas and divide by the Gas
Factor of the cal gas. The calculated value is the correct number to enter into the menu as the Gas Factor.

For example, if calibrating with methane when propane is the target gas, the correct Gas Factor to enter would
be 0.63/1.0 = 0.63.

For example, if calibrating with butane when ethane is the target gas, the correct Gas Factor to ent er wou ld be

0.38/0.72=0.53.
Table 1 shows the Gas Factors of most combustible hydrocarbon gases that will be measured. Find the gas of

interest for the cal gas and the target gas and follow the above instruction. If there is a mixture of target gases,
use a weighted approach to determine the correct Gas Factor.

For example, if the target gas was 50% butane and 50% pentane and the cal gas was methane, the correct Gas
Factor would be calculated and entered as ((0.5 x 0.77) + (0.5 x 0.77)) / 1.0 = 0.77.

Table 1 Gas Factors

From the Set Gas Factor text scroll, hold the magnet over PGM1 or PGM2 until the arrow prompt appears and
continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to scroll Set
Factor). The display will then switch to X.XX (where X.XX is the current gas factor). Swipe the magnet
momentarily over PGM2 to increase or PGM1 to decrease the gas factor level until the correct value is

CXT-IR Instruction Manual Rev. 1.6 Page 24 of 44

Model CXT-IR
displayed. Hold the magnet over PGM2 for 3 seconds to accept the new value. The display will scroll Factor

Saved, and revert to Set Gas Factor text scroll.

Move to another menu item by executing a momentary hold, or, return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Set Gas Factor four times and then return to normal
operation).

3.4.5 Bump Test

Bump Test is used to check the response of the sensor with the indication of response limited to the display
only. The results of the bump test will not affect the reading register on the Modbus™ output.

The menu item appears as: Bump Test

From the Bump Test text scroll, hold the magnet over PGM1 or PGM2 un til the arrow prompt appears and
continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to scroll Bump
Test Started).

The display will return to normal operation alternating between the live gas reading and showing Bump until 2
minutes expires or the execution of a momentary hold over PGM1 or PGM2, when the display will scroll

Bump Test Ended.

3.4.6 Restore Defaults

The CXT-IR sensor has the option to restore its internal memory settings to factory default conditions.

The menu item appears as: Restore Defaults.

From the Restore Defaults text scroll, hold the magnet over PGM2 until the arrow prompt appears and
continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to scroll Defaults
Restored). The display will then revert to Restore Defaults text scro l l.

Move to another menu item by executing a momentary hold, or, return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Restore Defaults four times and then return to normal
operation).

After the defaults are restored, the sensor must be recalibrated.

CAUTION

3.4.7 Set RF Channel

The CXT-IR sensor communicates wirelessly and can be set to use unique wireless radio channel. Set RF
Channel is used to set the RF radio channel. It is adjustable from 0 to 15.

The menu item appears as: Set RF Channel.

From the Set RF Channel text scroll, hold the programming magnet over PGM1 or PGM2 u ntil the arrow
prompt appears and continue to hold the magnet in place for an additional 3 to 4 seconds (until the display
starts to scroll Set Channel). The display will then switch to XX (where XX is the current RF channel). Swipe
the magnet momentarily over PGM2 to increase or PGM1 to decrease the hexadecimal number until the

CXT-IR Instruction Manual Rev. 1.6 Page 25 of 44

Model CXT-IR

desired ID is displayed. Hold the magnet over PGM2 for 3 to 4 seconds to accept the new value. The display
will scroll Channel Saved, and revert to Set RF Channel text scroll.

Move to another menu item by executing a momentary hold, or, return to Normal Operation via automatic
timeout of about 15 seconds (the display will scroll Set RF Channel four times and then return to Normal
Operation).

3.4.8 Set Modbus™ ID

The CX T-IR sensor can be polled serially via RS-485 Modbus™ RTU. Set Modbus™ ID is used to set the
Modbus™ serial ID address. It is adjustable from 01 to 256 in hexadecimal format (01-FF) hex.

The menu item appears as: Set Modbus™ ID.

From the Set Modbus™ ID text scroll, hold the programming magnet over PGM1 or PGM2 until the arrow
prompt appears and continue to hold the magnet in place for an additional 3 to 4 seconds (until the display
starts to scroll Set ID). The display will then switch to XX (where XX is the current ID address). Swipe the
magnet momentarily over PGM2 to increase or PGM1 to decrease the hexadecimal number until the desired
ID is displayed. Hold the magnet over PGM2 for 3 to 4 seconds to accept the new value. The display will
scroll ID Saved, and revert to Set Modbus™ ID text scroll.

Move to another menu item by executing a momentary hold, or, return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Set Modbus™ ID four times and then return to normal
operation).

3.5 Fault Diagnostic/Failsafe Feature

If the ITM should incur a fault, the Global Fault bit will be set on the Modbus™ output. This can occu r if the
ITM detects a problem with the sensor, detects that there is no sensor connected, if the ITM has an internal
fault, or other fault condition. The Global Fault bit will be set on the Modbus™ output until the problem is
resolved. The display will show the Fault when a magnetic programming tool is swiped across either PGM1 or
PGM2. The error codes are defined in Section 6Troubleshooting Guide.

CXT-IR Instruction Manual Rev. 1.6 Page 26 of 44

Model CXT-IR

Address Field

Function Code

Data

CRC

4. Modbus™ TM Communications

Modbus™ communication with a CXT Sensor is normally accomplished using another wireless transceiver
such as the RXT-320 which is connected through a RS-485 interface to a Modbus™ master control unit. The
control unit can then access the Modbus™ registers within the CXT to obtain readings and status of the sensor.

As with normal Modbus™ operation, there can be only one Modbus™ master that polls all the other devices
on the network which are considered Modbus™ slaves. Each sensor must have a unique Modbus™ address
and be on the same RF channel (for communication) to work properly on the wireless network. Both the
Modbus™ ID and the RF channel are set on the CXT sensor using the display.

The Modbus™ master control unit with RXT-320 transceiver (or equivalent) is responsible for broadcasting
requests and receiving slave device responses. The CXT sensor receives these requests through its own
internal transceiver and responds if the Modbus™ address and proper register set matches. The response will
be received by the RXT-320 and presented to the master control unit across the RS-485 interface.

4.1 General Modbu s™ De scr ip ti on

The Modbus™ communication uses the RTU transmission mode per the Modbus™ specification. The basic
frame format for Modbus™ consists of a Modbus™ address, function code, data and CRC.

Figure 17 Modbus™ Frame Format

The Modbus™ ID Field is the unique Modbus™ address of each device on the network. The Function Code is
the function to be performed. The Data contains read or write data and is formatted according to the function
being performed. The CRC (Cyclic Redundancy Code) is used to detect errors in the frame. Frames with errors
are invalid and ignored.

Modbus™ transactions consist of both a request by the controller and response from the device being
addressed so there are two frames transferred for every transaction. Every request is evaluated by the CXT to
determine if it is addressed to it, and if it falls within the register address range. If these two conditions are
true, the CXT will then check to see if it is a valid Function Code. Function Codes supported by the CXT are:

• Function Code 03 (03h) – Read Holding Registers

• Function Code 06 (06h) – Write Single Register

• Function Code 16 (10h) – Write Mult iple Reg ist ers

If an invalid function code is performed, the CXT will ignore the request by default and the controller will
timeout and continue with the next transaction.

4.1.1 Modbus™ Exceptions

The CXT is capable of returning Modbus™ exceptions when it cannot service a Modbus™ request meant for
that CXT. By default this is turned off since it can cause issues with some controllers that do n ot process
Modbus™ exceptions (See Section 4.2.2.4 Register – Control). The following exception codes are supported
and returned when Modbus™ exceptions are enabled:

CXT-IR Instruction Manual Rev. 1.6 Page 27 of 44

Model CXT-IR

Exception

Code

Unsupported function code. Only 03, 06 and 16 are
supported.

Invalid register address detected. If any request for registers

exception code will be returned.

NOTE: When using Detcon controllers, Modbus exceptions should be turned off.

Controllers that generate Modbus™ broadcast requests to the CXT must ensure a
turnaround delay of 150ms is met otherwise the next request can cause the broadcast
request to be overwritten and ignored.

A write to a Read Only register is allowed and returns a response, but it does not change the
value of the register. In some devices this would return an exception code.

Table 2 Exception Codes

Name Meaning

01 Illegal Function

02 Illegal Data Address

outside of the valid register address for the CXT occurs, this

There are other exception codes defined in Modbus™ but these are the only ones used by the CXT.

4.1.2 Modbus™ Broadcast Requests

The Modbus™ broadcast request was introduced in the CXT to support commands to be executed across all
CXT transceivers simultaneously. This is used to place all CXTs in a low power state for a specified time to
conserve battery life. Only the transceivers (radio) are placed into a low power state, the CXT sensor will
continue to operate normally. If none of the CXTs are battery powered then there is no need to issue a
command to place the transceivers in low power mode.

According to the Modbus™ specification a broadcast request is defined as a request with the Address Field
set to 0 and is used only for writing. There is no response returned as with normal Modbus™ transactions
since all devices on the system are accessed at the same time. Both Function Codes 06 and 16 (write s) are
supported with a broadcast request on the CXT.

Since there is no response on the broadcast request, there is a requirement to wait for a period of time before
sending out the next request. This allows all slave devices to process the command before the next request is
received, also known as the turnaround delay. This turnaround delay should be approximately 150
milliseconds for broadcast requests sent to the CXT. Controllers in general can meet this timing because it
takes longer than this to generate the next request so it may be unnecessary to make any adjustments.

NOTE

Broadcast requests are not confined to commands to put the network in low power mode, but can be used
where any normal write command is used.

4.2 Modbus™ Register Map and Directions

When the CXT is assigned a Modbus™ address, the following registers become available to the controller for
access. All CXT sensors implement this register set. Some registers are Read Only (R) and others are
Read/Write (R/W) as shown by the R/W column. This equates to specific function codes where Read is
function code 03 and Write is function code 06 or 16.

NOTE

The regi ster map (Table 3) for the CXT sensor gives a brief description for each register or register set. This
information is only meant as a reference. The registers are divided into two sections, one for the CXT sensor

CXT-IR Instruction Manual Rev. 1.6 Page 28 of 44

Model CXT-IR

0000

CXT-IR-100 Device Type

R

= 36

0001

Range

R/W

Detectable Range

0002

Reading

R

Current Gas Reading

0003

Calibration Level

R/W

Auto Span Level

0004

Life

R

Sensor Life

0005

Sensor Faults

R

Fault bits

0006

Sensor Model

R

DM (set to 1)

0007

Days since Calibration

R

0008

Reserved

R

0009

Reserved

R

0010

Sensor Temperature

R 0011

DECIMAL

R/W

0012

Temperature Compensation

R/W

0013

Reserved

R

0014

COUNTS

R/W

0015

CONTROL

R/W

0016

String

R

Set during production/test

0017

String

R

Set during production/test

0018

String

R

Set during production/test

0019

String

R

Set during production/test

0020

String

R

Set during production/test

0021

String

R

Set during production/test

0022

Reserved

R/W

NOT USED

0023

Sensor Controller Version

R

Year.Week

0024

Reserved

R 0025

Reserved

R

0026

Reserved

R

0027

Wireless Controller Version

R

Major.Minor

0028

Reserved

R

0029

Radio Firmware Version

R

00.Major

0030

Radio Firmware Version

R

Minor.Build

0031

Radio Software Version

R

Major.Minor

0032

Wireless ID High

R

00.XX

0033

Wireless ID Low

R

XX.XX

0034

RF Channel

R

Wireless RF Channel (Set in Display)

0035

Network ID

R

Defaults to RF Channel (Set in Display)

0036

Modbus Address

R

CXT Modbus Address (Set in Display)

RXT-320 Compatible Registers for Wireless Transceiver

8192

RXT-320 Device Type

R

22 (for compatibility)

8193

Reserved

-- 8194

Reserved

--

8195

Reserved

--

8196

Reserved

-- 8197

Reserved

-- 8198

Reserved

--

and the other for the CXT transceiver. For a more detailed description of the Register Map please contact
Detcon.

Table 3 CXT-IR Register Map

Offset Name R/W Comment

CXT-IR Instruction Manual Rev. 1.6 Page 29 of 44

Model CXT-IR

Offset

Name

R/W

Comment

8199

Battery Life in Percent

R

Smart Battery Life remaining in percent

8200

Battery Life in Minute

R

Smart Battery Life remaining in minutes

8201

Wireless Controller Version

R

same as register 0027

8202

RF Update Rate

W

Number of seconds to power down transceiver

8203

Control

R/W

Wireless Control

8204

Status

R

Wireless Status

8205

Input Voltage

R

Smart Battery voltage or Input Voltage to A/D

8206

Battery Error Count

R/W

Smart Battery read error count if detected

8207

Reserved

--

8208

Timestamp[0]

R

Time since power applied -- Seconds High

8209

Timestamp[1]

R

Time since power applied -- Seconds Low

8210

Timestamp[2]

R

Time since power applied -- Milliseconds

4.2.1 CXT Sensor Registers

4.2.1.1 Sensor Faults – Register 0005

The sensor fault status register consists of High and Low Status Bits. These bits are set/reset as faults occur or
are cleared. Each bit has a particular meaning:

Register # High Byte Low Byte
0005 Status Bits Status Bits

Bits read as 0 are FALSE; bits read as 1 are TRUE

Status Bits High Byte

Bit 15 – Reserved
Bit 14 – Calibration Mode
Bit 13 – Reserved
Bit 12 – Zero Fault
Bit 11 – Range Fault
Bit 10 – Reserved
Bit 9 – Clearing Fault
Bit 8 – Reserved

Status Bits Low Byte

Bit 7 – Sensor Fault
Bit 6 – Processor Fault
Bit 5 – Memory Fault
Bit 4 – Reserved
Bit 3 – Reserved
Bit 2 – Temperature Fault
Bit 1 – Auto Span Fault
Bit 0 – Global Fault

CXT-IR Instruction Manual Rev. 1.6 Page 30 of 44

Model CXT-IR

4.2.2 CXT Transceiver Registers

4.2.2.1 Battery Info – Multiple Registers

If a Detcon smart battery pack is connected to the CXT, there are five registers associated with information
about that battery. The CXT utilizes the I

2

C interface to read battery status and only one Detcon battery pack

can be read per CXT.

The controller can determine if a battery is present by reading the Status Register (register 8204). Th ere are
two bits in this sixteen bit register pertaining to the battery, Battery Detect – bit 4 (lowest bit is 0) and Battery
Fault – bit 5. Both bits default to a value of 0. Battery Detect will be set once the first read of the battery over

2

the I

C interface was successful. Battery Fault will be set if a battery was detected but the last read failed.
Battery Fault is re-evaluated upon every read of the battery which is set to approximately every 5 seconds.
Register 8206 (I

2

C Batt Read Fails) will increment by 4 each time there is a failure since there are 4 attempts

before declaring failure. This register can be cleared by writing a 0 to it at any point.

Once the battery has been detected the controller can read the battery life (registers 8199 and 8200). The
battery adjusts these values based upon the average current usage. If this usage varies widely over time it will
take some time to re-adjust the battery life readings. For instance an Alarm Station with no alarms will
consume a very small amount of battery but when Alarms are active this will jump to a much higher level of
usage. So in this case battery life may go from several weeks down to several hours.

The battery life is presented in two forms, life remaining in percentage (register 8199) and life remaining in
minutes (register 8200). The battery Life remaining is percentage is a value between 0 and 100 and battery life
in minutes is an unsigned value between 0 and 65535. Both readings are generally necessary to provide
appropriate feedback to the user. Life in minutes is the best for determining when to change the battery. For
example if the user wanted to be notified a day before the battery needed to be changed, the user could set a
threshold in the controller to be notified of low battery after 1440 minutes (1 day).

Since 65535 is the maximum value for life remaining in minutes, this represents a maximum of 45.5 days.
The battery life for an application can be much greater than this value and will remain at a reading of 65535
until it drops below this. Life in percentage was added for this reason. Percentage will track starting at 100
percent and drop down as battery life decreases. The controller can therefore use both registers, one to
represent usage in percentage to present to the user and then use the life in minutes to set a threshold on when
a low battery condition exists for changing the battery.

4.2.2.2 Wireless Controll er Ve rsi on

This is set to a value based upon the version of firmware programmed into the RXT-320 microcontroller. It is
stored as two byte value representing the major and minor revision numbers. So a 0113h (275 decimal)
represents a major version of 01 and minor version of 13. As software is updated this will be incremented
appropriately.

4.2.2.3 Register – Update Rate

The update rate represents the amount of time in seconds the CXT transceiver will be in a low power state. Its
main purpose is to provide a mechanism to place all wireless transceivers in a system into a low power mode
to conserve battery power. If there are no batteries used within the network of wireless transceivers this
register would not be utilized.

Upon power up, this register is set to 0 and the CXT transceiver is not in low power mode. To place a network
to low power mode the controller will generate a broadcast request (Modbus™ address = 0) and do a single

CXT-IR Instruction Manual Rev. 1.6 Page 31 of 44

Model CXT-IR

write (function code 06) to register 8202 with the number of seconds the network should go into low power
mode. During low power mode, there can be no access to any device on the network so changes in sensor
readings will not be updated. Once a non-zero value is written to this register on all transceivers, they will
begin counting down until the Update Rate register reaches zero, at which time all transceivers should be
active again and ready for network communication. The controller will monitor the update rate time remaining
by accessing Update Rate register on the RXT-320 (or equivalent) that it is attached. The Modbus™ interface
remains active, only the wireless network is placed in a low power state. The value of this register can be
between 0 and 65535 which allows a maximum low power time of 18.2 hours. Removal of power will reset
Update Rate to 0 and the transceiver will be active again.

4.2.2.4 Register – Control

The CXT transceiver control register is generally unused and should not be written to normally. Using the
control register, the CXT can be reset and Modbus™ exceptions can be enabled. Each bit in the control
register can control a particular function and should be read first then modify the bits needed and written back.
The default state of the register is 0. All reserved bits should always be set to a 0 when writing.

The bit assignments are:

Bit 15: Reserved (set to 0)
Bit 14: Reserved (set to 0)
Bit 13 – 12: Reserved (set to 0)
Bit 11: Modbus™ Exceptions Enabled
Bit 10 – 08: Reserved (set to 0)
Bit 07: Reset the microcontroller and wireless radio
Bit 06: Reset the microcontroller
Bit 05 – 00: Reserved (set to 0)

4.2.2.5 Register – Status

This register contains status of the CXT transceiver and some of the bits have already been covered in the
battery description. These default to 0 upon reset. The bit assignment and description are given below.

Bit 15 – 08: Reserved (set to 0)
Bit 07: Reserved (set to 0)
Bit 06: Reserved (set to 1)
Bit 05: I2C Fault on last read of Battery Status
Bit 04: Battery Detected
Bit 03: Reserved (set to 0)
Bit 02: Reserved (set to 1)
Bit 01: Reserved (set to 0)
Bit 00: Reserved (set to 0)

4.2.2.6 Register – Timestamp

Three registers are utilized to maintain a timestamp that increments on the microcontroller after power up.
These are all set to 0 upon power up or a microcontroller reset. The first two registers 8208 and 8209 are
internally combined into a single 32 bit register and incremented each second. The last register 8210 maintains
the millisecond count and will count from 0 to 999 and start over again.

CXT-IR Instruction Manual Rev. 1.6 Page 32 of 44

Model CXT-IR

The safety approvals require removing entire sensor assembly to a non-hazardous area
before changing out the batteries or battery pack.

The safety approvals require removing entire sensor assembly to a non-hazardous area
before changing out the batteries or battery pack.

5. Service and Maintenance

Calibration Frequency

In most applications, monthly to quarterly span calibration intervals will assure reliable detection. Upon initial
installation and commissioning, close frequency tests should be performed, weekly to monthly. Test results
should be recorded and reviewed to determine a suitable calibration interval due to differences in industrial
environments.

Visual Inspection

The Sensor should be inspected annually for the following:

• Inspect the sensor for signs of corrosion, pitting, and water damage.

• Remove the Splash Guard and inspected it for blockage, broken, cracked, or missing pieces.

• For H2S Sensor assemblies, inspect CXT-IR Series Splashguard Adapter Assembl y with integral filter

(PN 602-003552-100) for blockage of filter material.

• Inspect inside of the Junction Box for signs of water accumulation, signs of corrosion.

• Check wiring to ensure there are no loose or pinched wires and all connections are clean and tight.

Condensation Prevention Packet

A moisture condensation packet (Detcon PN 960-202200-000) should be installed in every explosion proof
Junction Box. The moisture condensation prevention packet will prevent the internal volume of the J-Box from
condensing and accumulating moisture due to day-night humidity changes. This packet provides a critical
function and should be replaced annually.

5.1 Replacement of the Batteries/Battery Pack

5.1.1 Units with 12V Smart Battery Pack

The CX T-IR Sensor incorporates a ‘Low battery’ fault message which will appear as an alternating display
between the current gas reading and ‘VOLT’ on the sensor display. This fault will appear when the battery
voltage drops below 7.5 volts. When the voltages drops below 7.2 volts the display will change to a steady
‘VOLT’ display, the sensor will then enter into ‘Fault’ mode, and the sensor will no longer provide a valid gas
reading.

NOTE

1. Remove the cover from the J-box.

2. Unlatch the holding lever on the side of the battery bracket, and swing the cover away from the battery

pack.

3. Remove the battery pack from the J-box, and replace with new battery pack.

4. Swing the cover back over the battery pack, and ensure that it is latched.

5. Replace the cover on the J-box.

5.1.2 Units with Tri-‘C’ sized Lithium Battery Holder

NOTE

CXT-IR Instruction Manual Rev. 1.6 Page 33 of 44

Model CXT-IR

Release Screws to

(+)

(+)

(+)

(-)

(-)

(-)

Positive connections to

batteries have coiled spring.

Use only 3.6V

1. Remove the cover from the J-box

2. Press Tri-C Battery Holder down slightly to disengage latch and rotate counter-clockwise according to

instructions on lid to remove from Enclosure Base. Lift Battery Holder from Enclosure Base.

3. Unscrew the cover screws on the battery holder. The screws are captive screws, removal of the screws

is not necessary.

4. The orientation of batteries is marked on the inside of the cover and the holder. Remove the batteries

from the battery holder.

5. Replace the batteries with the same type (Detcon PN 360-026500-000). It is permissible to use only

Tadiran Model TL-5920 batteries. Do NOT use regular ꞌCꞌ size batteries, as this may cause damage to
the sensor assembly.

6. All three batteries must be replaced at the same time

7. Pay attention to the orientation of the batteries when installing batteries in the Battery Holder. The

negative (minus) leads of the battery should connect with the negative (minus) leads of the battery
holder. The positive (plus) leads of the batteries should connect with the positive (plus) leads of the
battery holder.

allow access to
remove/replace
batteries.

batteries have raised bump.

Negative connections to

Lithium Batteries

Figure 18 Battery Orientation Diagram

8. Reattach the battery cover using screw s.

9. Re-install Tri-C Battery Holder in Enclosure Base, pressing down and rotating clockwise to secure.

The Battery Holder will ‘Snap’ into position when correctly oriented.

10. Replace the cover on the J-box.

CXT-IR Instruction Manual Rev. 1.6 Page 34 of 44

Model CXT-IR

It is not necessary to remove power while changing the plug-in combustible gas sensor in
order to maintain area classification, since it is intrinsically safe.

NOTE

Only replace the plug-in sensor with an authorized CXT-IR family of gas sensors.

ITM

(Bottom View)

Display
Window

Plug in Sensor

(Bottom view)

Locking

Setscrew

Locking

Setscrew

detcon inc

.

MODEL

CXT-IR

It is necessary to remove power to the Junction box while changing the ITM in order to
maintain area classification .

5.2 Replacement of Plug-in Sensor

NOTE

Figure 19 Sensor Cell and ITM Mating

1. Use a

1

/16" Allen wrench to release the locking setscrew that locks the ITM and splashguard adapter

assembly together (One turn only - Do not remove setscrew completely).

2. Remove the splashguard.

3. Unthread and remove the splashguard adapter assembly from the ITM.

4. Gently pull the plug-in sensor out of the ITM. Verify the gas type and range of the new sensor cell is

correct.

5. Orient the new plug-in sensor so that it matches with the female connector pins. When properly

aligned, press the sensor in firmly to make the proper connection.

6. Thread the splashguard adapter assembly onto the ITM to a snug fit and tighten the locking setscrew

using the

1

/16" Allen wrench.

7. Install the splashguard.

8. Check and perform zero calibration and span calibration as per Section 3.3.

5.3 Replacement of ITM – Aluminum Junction Box

1. Remove the power source to the sensor assembly.

2. Remove the battery pack from the J-box.

3. Disconnect all sensor wire connections at the Junction Box Terminal Board, taking note of the wire

connections, and disconnect the RF cable connector.

NOTE

4. Use a wrench and the wrench flats provided at the top section of the ITM and unthread the ITM for

removal.

CXT-IR Instruction Manual Rev. 1.6 Page 35 of 44

Model CXT-IR

It is necessary to remove power to the Junction box while changing the ITM in order to
maintain area classification .

5. Use a 1/8" Allen wrench to release the locking cap head screw that locks the ITM and splashguard

adapter assembly together (One turn only - Do not remove setscrew completely).

6. Unthread and remove the splashguard adapter assembly and splashguard from the ITM. These will be

re-used with the new ITM.

7. Gently remove the plug-in combustible gas sensor from the old ITM and install it in the new ITM.

Orient the plug-in sensor pins so that it matches the female connector pins on the new ITM then press
the sensor in firmly to make proper connection.

8. Thread the splashguard adapter assembly onto the new ITM until snug, tighten the locking cap head

screw and reinstall splashguard.

9. Feed the sensor assembly wires and RF cable through the

3

/4" female NPT port and thread the
assembly into the J-box until tight and the ITM faces toward the front access point. Use the locking
nut to secure the ITM in this position.

10. Re-connect the sensor assembly wires to the terminal board inside the Junction Box.

11. Re-connect the RF cable to the antenna cable.

12. Install the battery pack.

13. Check and/or perform Zero Calibration and Span Calibration in accordance with Section 3.3.

5.4 Replacement of ITM – Stainless Steel Mini Condulet

1. Remove the cover of the battery holder, and remove the batteries. Remove the battery holder from the

j-box by removing the two 6-32 screws at the bottom of the housing.

NOTE

1. Disconnect the sensor wire connections from the shorting blocks, taking note of the wire connections.

Disconnect the RF cable connector. (The wire splice shorting blocks can be difficult to remove wires
from. By using a pair of needle nose pliers and twisting the wires while pulling them out of the
shorting blocks can make the task easier.)

2. Use a wrench and the wrench flats provided at the top section of the ITM and unthread the ITM until it

can be removed.

3. Use a 1/8” Allen wrench to release the locking cap head screw that locks the ITM and Splashguard

Adapter Assembly together (One turn will suffice - Do not remove setscrew completely).

4. Unthread and remove the Splashguard Adapter Assembly and Splash Guard from the ITM. These will

be re-used with the new ITM.

5. Gently remove the plug-in toxic gas sensor from the old ITM and install it in the new ITM. Orient the

plug-in sensor pins so that they match the female connector pins on the new ITM and press the sensor
in firmly to make proper connection.

6. Thread the Splashguard Adapter Assembly onto the new ITM until snug, tighten the locking cap head

screw and reinstall Splash Guard.

7. Feed the sensor assembly wires and RF cable through the ¾” female NPT port and thread the

assembly into the J-box until tight and the ITM faces toward the front access point. Use the locking
nut to secure the ITM in this position.

8. Re-connect the sensor assembly wires to the shorting blocks by pushing the wire straight into the

block board inside the Junction Box. (Red to red, and black to black. Re-connect the RF cable to the
antenna cable.

9. Re-install the battery holder in the J-box, and re-install the batteries into the housing. Replace the

battery holder cover.

10. Check and/or perform Zero Calibration and Span Calibration per sections 3.3.1 AutoZero and 3.3.2

AutoSpan.

CXT-IR Instruction Manual Rev. 1.6 Page 36 of 44

Model CXT-IR

6. Troubleshooting Guide

If the ITM detects any functional errors the ITM will display the fault. If the sensor is experiencing a fault
condition a momentary swipe of the magnet will cause the ITM to scroll the fault condition(s) across the
display before the ◄ or ► prompt will appear.

The Display Error Codes are:

Auto Span Fault
Temperature Fault
Memory Fault
Processor Fault
Clearing Fault
Range Fault
Missing Sensor Cell Fault
Sensor Fault
Zero Fault
Low Battery Fault

Some faults are self-explanatory, and if these faults occur and cannot be cleared the ITM should be replaced
first to see if the fault will clear. Other faults may need further investigation. Some of the sensor problems,
associated error codes, and resolution s are lis ted belo w.

Missing Sensor Cell Fault

Probable Cause: The sensor cell is not installed, is installed incorrectly, or is nonoperational.

• Replace the Sensor Cell with a known good Sensor Cell.

Sensor Fault

Probable Cause: The sensor optics have become too dirty to support functionality.

• Replace the Sensor Cell with a known good Sensor Cell.

Under-Range problems

Probable Cause: Sensor baseline drifted lower, interference gases,

• Perform zero calibration.

• Use zero air or N

• Allow more time for zero stabilization if this is a biased sensor type.

• Execute successful span calibrat ion. (S ec tion 3.3.2AutoSpan)

• Replace plug-in combustible sensor if error continues.

Stability problems

Probable Causes: Failed sensor, empty or close to empty cal gas cylinder, problems with cal gas and delivery

• Check validity of span gas using pull tube or other means (check MFG date on cal gas cylinder).

• Use proper cal gas regulators and tubing for highly corrosive gases.

• If using Splashguard with Integral Cal Port, must use Calibration Wind Guard or air movement can

compromise span gas delivery.

• Check for obstructions affecting cal gas hitting sensor face (including being wet, blocked, or

corroded). Sensor assemblies use CXT-IR series splashguard adapter assembly with integral filter.
Clean or replace if necessary.

• Replace the plug-in combustible sensor.

source. (Section3.3.1AutoZero)

2

CXT-IR Instruction Manual Rev. 1.6 Page 37 of 44

Model CXT-IR

Contact the Detcon Service Department for further troubleshooting assistance at
281-367-4100.

Clearing problem

Probable Causes: Failed sensor, cal gas not removed at appropriate time, problems with cal gas and delivery,
background of target gas.

• The sensor must recover to < 10% of range in < 5 min after Span calibration is complete

• Use bottled air (zero air or N

) if there is a known continuous background level.

2

• Check validity of span gas using pull tube or other means (check MFG date on cal gas cylinder).

• Use proper cal gas regulators and tubing for highly corrosive gases

• Check for obstructions affecting cal gas hitting sensor face (including being wet, blocked, or

corroded). Sensor assemblies use CXT-IR series splashguard adapter assembly with integral filter.
Clean or replace if necessary.

• Replace the plug-in combustible sensor.

Poor Calibration Repeatability

Probable Causes: Failed sensor, use of wrong cal gas or problems with cal gas and delivery, interference gases.

• Check validity of span gas with regulator and sample tubing in place using pull tube or other means

(check MFG date on cal gas cylinder).

• Use proper cal gas regulators and tubing for highly corrosive gases (HF, HCI, Cl2, NH3, HBR, F2,

etc.)

• Check for obstructions affecting cal gas hitting sensor face (including being wet, blocked, or

corroded). Sensor assemblies use CXT-IR series splashguard adapter assembly with integral filter.
Clean or replace if necessary.

• Replace the plug-in combustible sensor.

Unstable Output/ sudden spiking

Possible Causes: Unstable power supply, inadequate grounding, or inadequate RFI protection.

• Verify power source is stable.

• Verify field wiring is properly shielded and grounded.

• Contact Detcon to optimize shielding and grounding.

• Add Detconꞌs RFI Protection Circuit accessory if problem is proven RFI induced.

Nuisance Alarms

• Check condulet for accumulated water and abnormal corrosion on terminal board.

• If nuisance alarms are happening at night, suspect condensation in condulet.

• Add or replace Detconꞌs Condensation Prevention Packet (PN 960-202200-000).

• Investigate the presence of other target gases that are causing cross-interfere nce si g nals.

• Determine if cause is RFI induced.

Transmitter not respondi ng

• Verify condulet has no accumulated water or abnormal corrosion.

• Verify required batteries are installed and have enough charge to power the sensor.

• Swap with a known-good ITM to determine if ITM is faulty.

Low Battery / Low Voltage Fault

Possible Cause: Lithium Ion batteries are depleted.

• Change out all three of the Lithium Ion non-rechargeable ‘C’ size batteries with new batteries.

NOTE

CXT-IR Instruction Manual Rev. 1.6 Page 38 of 44

Model CXT-IR

7. Customer Support and Service Policy

Detcon Headquarters

Shipping Address: 4055 Technology Forest Blvd, Suite 100, The Woodlands Texas 77381
Mailing Address: P.O. Box 8067, The Woodlands Texas 77387-8067
Phone: [phone], or 281.367.4100
Fax: [phone]

• www.detcon.com

• [e-mail]

• [e-mail]

All Technical Service and Repair activities should be handled by the Detcon Service Department by phone,
fax or e mail thr ough the cont act information given above. RMA numbers should be obtained from the Detcon
Service Department prior to equipment being returned. For on-line technical service, customers should have
ready the model number, part number, and serial number of product(s) in question.

All Sales activities (including spare parts purchase) should be handled by the Detcon Sales Department via
phone, fax or email at contact information given above.

Warranty Notice

Detcon Inc. warrants the Model CXT-IR gas sensor to be free from defects in workmanship of material under
normal use and service for one year from the date of shipment on the transmitter electronics. See Warranty
details in Section 8.

Detcon Inc. will repair or replace without charge any such equipment found to be defective during the
warranty period. Full determination of the nature of, and responsibility for, defective or damaged equipment
will be made by Detcon Inc. personnel.

Defective or damaged equipment must be shipped to the Detcon Inc. factory or representative from which the
original shipment was made. In all cases, this warranty is limited to the cost of the equipment supplied by
Detcon Inc. The customer will assume all liability for the misuse of this equipment by its employees or other
contracted personnel.

All warranties are contingent upon the proper use in the application for which the product was intended and
does not cover products which have been modified or repaired without Detcon Inc. approval, or which have
been subjected to neglect, accident, improper installation or application, or on which the original identification
marks have been removed or altered.

Except for the express warranty stated above, Detcon Inc. disclaims all warranties with regard to the products
sold. Including all implied warranties of merchantability and fitness and the express warranties stated herein
are in lieu of all obligations or liabilities on the part of Detcon Inc. for damages including, but not limited to,
consequential damages arising out of, or in connection with, the performance of the product.

CXT-IR Instruction Manual Rev. 1.6 Page 39 of 44

Model CXT-IR

8. CXT-IR Sensor Warranty

Detcon, Inc., as the manufacturer, warrants under intended normal use each new CXT-IR sensor to be free
from defects in material and workmanship for a period of one year from t he date of shipment to the original
purchaser. Should the sensor fail to perform in accordance with published specifications within the warranty
period, return to Detcon, Inc., for necessary repair or replacement. All warranties and service policies are FOB
the Detcon facility located in The Woodlands, Texas.

Terms & Conditions

• The original serial number must be legible on each sensor element base.

• Shipping point is FOB the Detcon factory.

• Net payment is due within 30 days of invoice.

• Detcon, Inc. reserves the right to refund the original purchase price in lieu of sensor replacement.

ITM Electronics Warranty

Detcon Inc. warrants, under intended normal use, each new Compact Wireless Sensor ITM to be free from
defects in material and workmanship for a period of one year from the date of shipment to the original
purchaser. All warranties and service policies are FOB the Detcon facility located in The Woodlands, Texas.

Terms & Conditions

• The original serial number must be legible on each ITM.

• Shipping point is FOB the Detcon factory.

• Net payment is due within 30 days of invoice.

• Detcon, Inc. reserves the right to refund the original purchase price in lieu of ITM replacement.

CXT-IR Instruction Manual Rev. 1.6 Page 40 of 44

Model CXT-IR

9. Appendix

9.1 Specifications

9.1.1 System Specifications

Sensor Type: Continuous diffusion/adsorption type

NDIR Non-Disperse Infrared
Sub-miniature plug-in replaceable ty pe

Sensor Life: 5 years typical

Measuring Ranges: 0-100% LEL, 0-100% by volume

Accuracy/ Repeatability: ± 3% LEL in 0-50% LEL range, ± 5% LEL in 51-100% LEL range

Response Time: T50 < 10 seconds, T90 < 30 seconds

Warranty: 1 year

9.1.2 Environmental Specifications

Operating Temperature: -40°C to +75°C
Storage Temperature: -40°C to +75°C
Operating Humidity: 0-100% RH (Non-condensing)

Operating Pressure: ±10% atmospheric pressure

9.1.3 Electrical Specifications

Input Voltage: 6-30VDC

Power Consumption: 25mW (typical), 420mW (max)

RFI/EMI Protection: Complies with EN61326

9.1.4 Mechanical Specifications

Length: 14.4 inches (365mm), includes splashguard

Width: 3.77 inches (96mm)

Weight: 5.5lbs (2.5kg), without batteries

CXT-IR Instruction Manual Rev. 1.6 Page 41 of 44

Model CXT-IR

92C-IR0205-100

CXT-IR Intelligent Transmitter Module

371-IR1II1-000

Replacement Plug-in sensor

500-005180-100

CXT Smart Battery Terminal Board

976-0BP303-012

Plug-in Battery Pack 12V 2200mAh (Rechargeable)

976-0BP303-290

Plug-In Battery Pack 12V 2900mAh (Rechargeable)

360-0265500-000

Lithium Primary 3.6V ‘C’ size battery (Not rechargeable)

360-036500-000

Battery, Lithium 3.6V 'D'-size (Not rechargeable)

960-202200-000

Condensation prevention packet (For condulet, replace annually)

602-003870-000

Tri-C Size Battery Holder Assembly

602-004402-000

D-Sized Battery Pack Assembly ( for 5 cell, replaceable, non-rechargeable)

6130

Sensor Rain Shield

602-003803-100

CXT-IR Splashguard Adapter Assembly

327-000000-000

Programming Magnet

Part Number

Calibration Accessories

943-000006-132

Threaded Calibration Adapter

943-050000-132

Span Gas Kit: Includes calibration adapter, span gas humidifier, 500cc/min
fixed flow regulator, and carrying case. (Not including gas).

See Detcon

Span Gases – various

943-05AM00-000

500 cc/min Fixed Flow Regulator for span gas bottle

Part Number

Optional Accessories

897-850800-010

NEMA 7 Aluminum Condulet Base

897-850400-010

NEMA 7 Aluminum Condulet Solid Cover

897-850500-010

NEMA 7 Aluminum Condulet w/Window Cover

897-860401-316

316SS Mini Condulet Extended Cover

897-860800-316

316SS Mini Condulet base

960-202200-000

Condensation prevention packet (For condulet, replace annually)

943-004365-000

Wireless Sensor Mounting Plate (for use with Standard Al condulet)

500-005180-100

CXT Smart Battery Terminal Board

303-734231-000

Insertion tool, CAGE Clamp Connector

9.2 Spare Parts, Sensor A c cessories, Calibration Equipmen t

Table 4 Spare Parts, Sensor Accessories, and Calibration Equipment

Part Number Spare Parts

Part Number Sensor Accessories

CXT-IR Instruction Manual Rev. 1.6 Page 42 of 44

Model CXT-IR

1.0

5/18/12

Initial Release

LBU

1.1

12/04/12

Adding note requiring removal of sensor assembly to
non-hazardous location to install or replace batteries

BM

1.2

2/20/13

Corrected title page, updated spare parts list, drawings

LBU

1.3

07/19/13

Updates for battery and sensor cell faults

BM

1.4

01/20/14

Add Calibration Wind Guard to Calibration Procedures

BM

1.5

02/10/14

Add detail to battery installation

BM

9.3 Revision Log

Table 5 Revision Log

Revision Date Changes Approval

CXT-IR Instruction Manual Rev. 1.6 Page 43 of 44

Model CXT-IR

Shipping Address: 4055 Technology Forest, Suite 100, The Woodlands, Texas 77381

Phone: [phone] • Fax: [phone] •www.detcon.com •

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Mailing Address: P.O. Box 8067, The Woodlands Texas 77387-8067

CXT-IR Instruction Manual Rev. 1.6 Page 44 of 44