DTSX200 Distributed Temperature Sensor

What Is Distributed Temperature Sensing?

Distributed temperature sensing (DTS) measures temperature distribution over the length of an optical fiber cable using the fiber itself as the sensing element. Unlike traditional electrical temperature measurement (thermocouples & RTD), the length of the fiber optic cable is the temperature sensor. Distributed temperature sensing can provide thousands of accurate and precise temperature measurements over a long distance. Compared to traditional electrical temperature measurements, distributed temperature sensing represent a cost effective method for obtaining accurate and high resolution temperature measurement.

Introducing Fiber-Optic Temperature Sensor, DTSX

Temperature monitoring throughout large plants without blank areas is difficult due to technical and cost issues and it is hard to comply with corporate HSE policies. DTSX measures temperature distribution over the length of an optical fiber cable using the fiber itself as the sensing element and it is ideal for temperature monitoring over long distances and wide areas. DTSX has been increasingly used in variety of applications such as fire detection, leak detection and preventative maintenance.


What Are the Advantages of Using DTS ?

  1. Cost
    When an application requires hundreds or thousands of sensors to be measured, it becomes very expensive to wire each individual sensor back to a data acquisition station. It is much more cost effective and beneficial to acquire accurate and high resolution temperature measurement using fiber optic cable.

  2. Long distance
    It is difficult to measure temperature over a long distance using traditional electrical measurement sensors. Not only can DTS fiber optic cable be deployed over a long distance but it also provides a high resolution profile of the area as well as accurate and precise temperature measurement over that distance.

  3. High electromagnetic noise environment
    DTS is isolated from electromagnetic noise because of its optical characteristics. Unlike traditional electrical measurement sensors (thermocouple & RTD) there is no electrical component within the optical fiber, therefore, it is immune to electromagnetic noise.
the advantages of using DTS


What Is DTSX200 Distributed Temperature Sensor ?

The DTSX200 adapts flexibly to the installation environment as a standard model. Using data obtained from temperature distribution measurement, we contribute to monitoring of plant facilities, maintenance and management of the integrity of high-temperature furnaces, and prevention of failures.

 Introduction of DTSX200

About OpreX

OpreX is the comprehensive brand for Yokogawa’s industrial automation (IA) and control business and stands for excellence in the related technology and solutions. It consists of categories and families under each category. This product belongs to the OpreX Field Instruments family that is aligned under the OpreX Measurement category.


Measurement Principle

Operating Principle

Operating principle

Yokogawa DTSX200 measures temperature and distance over the length of an optical fiber using the Raman scatter principle. A pulse of light (laser pulse) launched into an optical fiber is scattered by fiber glass molecules as it propagates down the fiber and exchanges energy with lattice vibrations. As the light pulse scatters down the fiber optic cable, it produces stokes signal (longer wavelength) and anti-stokes (shorter wavelength) signal, of which both signals shifted from the launch of the light source. The intensity ratio of the two signals components depends on the temperature at the position where the Raman scatter is produced. This temperature can thus be determined by measuring the respective intensities of the stokes and anti-stokes signals. Furthermore, part of the scattered light, known as the backscatter, is guided back towards the light source. The position of the temperature reading can thus be determined by measuring the time taken for the backscatter to return to the source.


Raman Scattering

All light interacts with matter! For example, imagine standing in a pitch black garage with no external light source. Inside this garage is a bright red sports car. Needless to say, you cannot see the sports car or the color of the sports car itself. However, when you turn on the lights to the garage, you can immediately see the light source reflecting the bright red color off the car. The light that is bouncing off the red sports car is only bouncing off the "red" spectrum, therefore, your eyes see the sports car as, well, red.

Raman scattering

This phenomena is also true when you shoot a pulse of light (laser pulse) off of a molecule, in this case, the fiber glass molecule in the optical fiber cable. When the light source enters the optical fiber cable, most of the light bounces (backscatter) back unchanged (no change in wavelength). However, a small amount of that light shifted/changed. That shift/change from the light source is called Raman Scatter. Since Raman Scatter is thermally influenced by temperature, the intensity depends on temperature. Distributed temperature sensing is capturing the shift/change from the propagating light pulse and measuring the intensities between the two signal components (stokes and anti-stokes).


Types of Scattering Light

Yokogawa's distributed temperature sensors measure temperature distribution using Raman scattering light, which exhibits particularly good temperature sensitivity among the following types of scattering light.

Types of Scattering Light Features Field of Application
Rayleigh Scattering
  • Caused by fluctuations in the density inside the medium
  • Same frequency components as those of incident light
  • Optical fiber loss distribution
    (OTDR:Optical Time Domain Reflectometer)
Raman Scattering
  • Caused by the interaction with molecular vibration inside the medium
  • The intensity of anti-Stokes rays is mainly dependent on temperature.
  • Temperature distribution
    (DTS:Distributed Temperature Sensor)
Brillouin Scattering
  • Caused by the interaction with sound waves inside the medium
  • The frequency is dependent on strain and temperature.
  • Strain distribution
    (DSS:Distributed Strain Sensor)
  • Temperature distribution

Measurement Method

Single-Ended Measurement Method

  • This method launches optical pulses into only one end of the optical fiber for sensing. Easy to install, it is effective when the measuring target is long range.

Single-ended measurement method


Double-Ended Measurement Method

  • This method launches optical pulses into both ends of a looped optical fiber for sensing.
  • This method allows for continued measurement even if on place of the fiber optic cable is broken.

Double-ended measurement method


Comparison of Measurement Methods

Measurement Method Advantages Disadvantages
Single-Ended Measurement Method
  • Compared to the double-ended measurement, the fiber optic sensor cable can be easily installed.
  • No optical switch is required.
  • Even if the optical fiber is broken, it is possible to continue measurement at points before the broken section.
  • It is impossible to compensate for position-based optical fiber loss fluctuations.
  • The temperature calibration is more complicated than the double-ended measurement.
Double-Ended Measurement Method
  • The optical fiber loss distribution along the optical fiber is automatically canceled out.
  • Yokogawa's method reduces the influence such as darkening.
  • If the optical fiber is broken, the measurement method is automatically switched to the single-ended measurement.
  • The installation of fiber optic sensor cable must be looped.
  • An optical switch is required.
  • The actual maximum distance range for temperatuer measurement is a half that for the single-ended measurement method.

Types of Temperature Sensors


Types of Temperature Sensors and Their Features

Type Features
Fiber Optic Sensor An optical fiber, used as the temperature sensor, is suitable for monitoring temperatures over a long distance and wide area. It allows you to identify specific locations on a per sampling-interval basis along the fiber optic sensor cable and to monitor the temperature at each location.
Thermo Camera This instrument detects infrared radiant energy from objects to measure temperatures. Capable of measuring temperature distributions over a wide area in a non-contact manner, it is suitable for monitoring temperatures of industrial furnaces, solids of revolution, and so on.
Resistance Thermometer This sensor uses the characteristic of the electrical resistance of metal that changes almost in proportion to temperature. Capable of accurate temperature measurement, it is suitable for industrial precision temperature measurement.
Thermocouple When two different metals are connected to each other, the temperature difference between the metals develops electromotive force at the connection. This sensor uses this electromotive force. Capable of measuring temperature over a wide area at low cost, it is widely used as a temperature sensor for industrial use.
Radiation Thermometer This thermometer measures temperatures by measuring the intensity of infrared rays from materials. As a non-contact thermometer capable of remote measurement, it is suitable for measuring ultra-high temperatures.


Comparison among Temperature Monitoring Methods

  Fiber Optic Sensor
Fiber Optic Sensor
Thermo Camera
Thermo Camera
Point Sensor
Point Sensor (Thermocouple)
Description Wide-area monitoring based on a fiber optic sensor Surface temperature monitoring based on a thermo camera Multipoint monitoring based on discrete sensors
Detection Method Contact Non-contact Contact
Range of Temperatures Monitored -200 to 300 °C
(Based on a sensor cable)
Normal temperature to 2000 °C
(Range switching required)
-200 to 1000 °C
(Type K thermocouple)
Area Coverage of a very wide area
DTSX200: up to 6 km / ch
DTSX3000: up to 50 km / ch
DTSX1: up to 16 km / ch
Small viewing angle of 20° Wide area
Advantages Coverage of a very wide area and seamless monitoring Capability of a limited tiny area monitoring Capability of a limited tiny area monitoring
Disadvantages Restricted to small areas Non-seamless monitoring Non-seamless monitoring
Installation and maintenance of compensating lead wires


Representative parameters that indicate the performance of distributed temperature sensors include the spatial resolution and temperature resolution. In spite of the fact that in general, there is a trade-off relationship between these parameters, we have realized high performance based on signal processing technology.


Spatial Resolution

  • The spatial resolution is the minimum length that detects changes in temperature (it is also referred to as the response distance).
  • The spatial resolution is defined as the length when a temperature change of 10 to 90 percent of the optical fiber for sensing is detected.
  • The sampling resolution represents the data interval, the definition of which is different from that of the spatial resolution.

Spatial Resolution


Temperature Resolution

  • The temperature resolution is defined by the standard deviation (1 σ) of measured values along the fiber optic sensor in a uniform temperature environment (in a thermostat chamber).
  • The temperature resolution is the indicator of variations, which does not indicate temperature accuracy (the use of a reference thermometer in calibration makes it possible to make measurements with a higher temperature accuracy).
  • Raman backscattering light is a very faint signal. By repeating measurements to average measured values, the distributed temperature sensors achieve a higher temperature resolution.

Temperature Resolution
Examples of measurement results (DTSX200)

Types of cables

You can choose the most suitable type according to your intended use.

Normal Operating Temperature Applications Cable Type Cable Details Features
Normal Temperature
  • Conveyor Fire Detection
  • Cable Temperature Monitoring
  • Bus Duct Temperature Monitoring
  • Cable Tunnel Fire Detection
  • Warehouse Fire Detection
  • Hot Spot Detection
  • Cold Spot Detection
Standard Type Standard type Image Zoom Nonmetal, lightweight, and easy to install
EN 54-22 certified
Robust Type Robust type Image Zoom Resistant to crush and tension and less likely to break
EN 54-22 certified
Flexible Type Flexible type Image Zoom Thin and flexible and easy to install along the measurement targets
High / Low Temperature
  • Blast Furnace Monitoring
  • Drying Furnace Monitoring
  • LNG Leak Detection
  • Well Monitoring
Steel Tube Type Steel tube type Image Zoom Thin and flexible and easy to install along the measurement targets
Steel Armored Type Steel armored type Image Zoom Resistant to crush and tension and less likely to break

Flexible System Construction That Adapts to a Wide Range of Applications

Temperature data is processed (zone and alarm settings and warnings are made) at a host system, allowing for flexible system construction according to the system size and your requirements.
If an optionally available PLC (FA-M3 or e-RT3) or recorder is incorporated, the system can produce a contact output when it gives a warning.

System Configuration Example : Image

【Example of a Host System】
SMATRDAC+ (recorder and data logging software), CI server and CENTUM (integrated production control system)

Product Introduction

DTSX200 Overview

The DTSX200 distributed temperature sensor is configured by a DTS module, an optical switch module, a base module, a power supply module, and so on.

DTSX200 Distributed Temperature Sensor

* DTS : Distributed Temperature Sensor

The distance to the target : 6 km Range

On the Partner Portal Member Site, you can check the details of the specifications.
GS 39J06B45-01 : DTSXM Distributed Temperature Sensor Middle Range System
GS 39J02B45-01 : DTSXM Distributed Temperature Sensor Middle Range System (Software)

Optical Switch Module

We provide three different types of optical switches.
They are module types, offering choices according to your intended use.

  • DTOS2 : 2 - channel optical switch module
  • DTOS4 : 4 - channel optical switch module
  • DTOS16 : 16 - channel optical switch module

Base Module

The base module for DTSX200 is used for mounting various function modules including the DTSX200 distributed temperature sensor, power supply modules, optical switch modules and CPU I/O modules

Power Supply Module

One of the following power supply modules must be selected.(* Input voltage range by model name)

  • NFPW426 : 10 to 30 V DC
  • NFPW441 : 100 to 120 V AC
  • NFPW442 : 220 to 240 V AC
  • NFPW444 : 21.6 to 31.2 V DC


DTRK10 Rack Mount Kit

The rack mount kit can be used for laying optical fibers in a cabinet.


DTSX3000 Control Visualization Software (DTAP3000)

The DTSX200 needs to process temperature measurement data at multiple points from multiple channels.
The DTAP3000 is application software specifically designed to facilitate making settings of all DTSX products (DTSX3000 / 200 / 1) and indicating measurement data. With a variety of functions, such as setting and control of the main unit of the DTSX200 and optical switch, indication of measurement results, analysis of changes in temperature, and setting and indication of alarms, the software provides you with information that helps you monitor temperature.


DTSX200 data conversion software (DTAP200D)

The DTAP200D is application software for converting data to the WITSML format, the standard format for the oil and gas markets. This software allows you to create data in the WITSML format directly from the DTSX200.


Refer to the General Specifications for detailed specifications.

DTSX 200

Item Specifications
Distance Measurement distance range 1 km, 2 km, 3 km, 4 km, 6 km
Sampling resolution 10 cm, 20 cm, 50 cm, 1 m
Spatial resolution 1 m (10 to 90 %)
Temperature Measurement temperature range -200 to 300 °C (dependent on the optical fiber for sensing)
Temperature resolution
(1 σ, without optical switch)
10 s
1 min
10 min
1 km
3 km
6 km
4.2 °C
Sensor optical fiber Optical fiber 50 / 125 μm GI
(No reflection at end of optical fiber)
Optical connector E2000 / APC
Interface Serial (RS-232C) 3 ports, non-isolated, RJ45 modular jacks
Full duplex, asynchronous
Function: Communication (Modbus)
Baud rate: 1.2, 2.4, 4.8, 9.6, 19.2, 38.4 57.6, 115.2 kbps
Function: Communication (Modbus)
Baud rate: 1.2, 2.4, 4.8, 9.6, 19.2, 38.4 kbps
Function: Maintenance (Private)
Ethernet interface LAN 1 port, 10BASE-T or 100BASE-TX,
RJ45 modular jacks, automatic negotiation,
automatic MDI, with Network power switch (ON/OFF)
Power supply Consumption Operating mode 10 W
Power save mode 2.1 W
Dimensions (W x H x D) 197.8 x 132.0 x 162.2 mm (6 slots width)
Weight 2.5 kg

Temperature calibration of the Sensor Optical Fiber for DTSX200 is required before temperature distribution measurement.

Optical Switch Module

Item Specifications
Insertion loss 0.6 dB (Typical)
1.4 dB (Max.)
1.0 dB (Typical)
3.0 dB (Max.)
0.8 dB (Typical)
1.4 dB (Max.)
Distributed temperature measurements Measurement type Single end, Double end
Sensor optical fibers Optical fiber 50 / 125 μm GI, closed end, non refraction required
Optical connector E2000 / APC
Optical channels 2 channels 4 channels 16 channels
Interface Control Controlled by DTSX200
Display LEDs: HRDY, RDY, Alarm, Active channel
Power supply Consumption 1 W 1 W Operating 4.5 W
Power save 1 W
Dimensions (W x H x D) 65.8 x 130.0 x 160.3 mm
(2 slots width)
65.8 x 130.0 x 160.3 mm
(2 slots width)
65.8 x 130.0 x 160.3 mm
(2 slots width)
Weight 0.6 kg 0.64 kg 0.75 kg

Note:  As a guideline, the module should be replaced periodically every 4.7, 6 and 9.5 years for continuous operation of 15-second, 20-second and 30-second measurements, respectively.


Item Specifications
Safety Standards CSA C22.2 No.61010-1-04
EN 61010-1:2010
EN 61010-2-030:2010
EN IEC 61010-2-201:2018
CU TR 004
EMC Standards CE Marking EN 55011:2016+A1:2017 Class A Group 1
EN 61000-6-2:2005
EN 61000-3-2:2014
EN 61000-3-3:2013
RCM EN 55011:2016+A1:2017 Class A Group 1
KC Marking Korea Electromagnetic Conformity Standard
EAC Marking CU TR 020
Laser safety Class IEC 60825-1:2007 Class1M
IEC/EN 60825-1:2014 Class1
FDA (CDRH) 21CFR Part 1040.10
Standards for Hazardous Location Equipment FM Nonincendive Class I, Division 2, Groups A, B, C, D T4
FM 3600-2018
FM 3611-2018
FM 3810-2005
ATEX Type "n" II 3 G Ex nA ic [op is Gc] IIC T4 Gc X
EN IEC 60079-0:2018
EN 60079-11:2012
EN 60079-15:2010
EN 60079-28:2015
CSA Non-Incendive Class I, Division 2, Groups A, B, C, D T4
C22.2 No. 0-10
CAN/CSA-C22.2 No. 0.4-04
C22.2 No. 213-M1987
Restriction of Hazardous Substances RoHS Directive EN IEC 63000:2018

Note: Under EU legislation, the manufacturer and the authorised representative in EEA (European Economic Area) are indicated below:
Manufacturer: YOKOGAWA Electric Corporation (2-9-32 Nakacho, Musashino-shi, Tokyo 180-8750, Japan).
Authorised representative in EEA: Yokogawa Europe B.V. (Euroweg 2, 3825 HD Amersfoort, The Netherlands).


Vehicle Lithium-ion Battery

Smart Monitoring of Manufacturing Process Shelves and Storage Shelves

Thermal runaway of lithium-ion batteries mounted on individual shelves is discovered at an early stage. This enables a quick initial response when an abnormality occurs to limit damage to a minimum.
(For details, refer to "Smart Monitoring of Manufacturing Process Shelves and Storage Shelves -In-vehicle Lithium-ion Battery Applications- ".)

Smart Monitoring of Manufacturing Process Shelves and Storage Shelves


Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process

Fires or dust explosions in exhaust air ducts for preventing the contamination of aluminum dust in the assembly process of lithium battery batteries are monitored. Abnormalities are not overlooked as ducts extending over long distances in blind areas such as roof space are comprehensively monitored. (For details, refer to “Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process -In-Vehicle Lithium-ion Battery Applications- ".)

Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process


Monitoring of Soundness of Power Supply Bus Bar

The joints of the power supply bus bar are monitored.
Abnormalities are not overlooked as fiber optic cable is built into the bus duct and bus bars extending over long distances in blind areas such as roof space are comprehensively monitored.
(For details, refer to "Monitoring of Soundness of Power Supply Bus Bar -In-vehicle Lithium-ion Battery Applications-".)

Monitoring of Soundness of Power Supply Bus Bar


Fiber Optic Cable Visualizes In-furnace Temperature Distribution

The DTSX fiber optic distributed temperature sensor can monitor temperature distribution every meter along the path of the fiber optic cable.
Thermocouples, etc. are used for heater control as up till now, and by adding DTSX to them, it will be possible to visualize the temperature distribution inside the entire drying furnace.
Resolving heater and other problems by utilizing the result, and passing products through the furnace after setting the in-furnace temperature to the ideal temperature profile result in improved productivity.

Fiber Optic Cable Visualizes In-furnace Temperature Distribution

When attempts are made to measure multiple points by thermocouples, etc., wiring is complicated, construction costs escalate and periodic maintenance of each individual sensor is required. This is unrealistic when applying it to multiple drying furnaces.
As the DTSX system requires only laying fiber optic cable inside the furnace, both initial and running costs can be reduced.
Moreover, a single DTSX can cover multiple drying furnaces, which improves cost effectiveness.
The DTSX has also been put to use in monitoring the temperature distribution in tunnel furnaces.
(For details, refer to "Fiber Optic Cable Visualizes In-furnace Temperature Distribution".)

Fire Detection

Early fire detection to critical process and environment is an important component to any safety system. A blazing fire has devastating consequences to important assets, products and most importantly, human lives. Furthermore, the cost of downtime due to fire leads to lost opportunities and costly repairs. Discrete sensor technology often fails due to the surrounding environment conditions such as dust, humidity, heat and corrosion. In addition, it is expensive to maintain a conventional sensor technology due to constant repair. Yokogawa's DTSX200 is designed to detect fire in critical assets under the most extreme conditions and offers unmatched reliability, performance and cost savings.

Yokogawa's DTSX200 is designed to deploy in the following fire detection applications:

  • Conveyor belts carrying important goods
  • Tank farms
  • Cable trays
  • Underground tunnels
  • Pipelines (underground, above ground)
  • Nuclear facilities
  • Mining, Refinery
Feature Benefits
1m special resolution Identify the exact location of the fire
Up to 0.1°C temperature resolution Possible fire detection within the first 10 seconds of occurrence *
Fiber optic cable sensor Unlike discrete sensor or IR camera, fiber optic cable eliminates "blind spots"
Coated fiber optic cable Immune to dust, humidity, corrosion and dirt
Report and data analysis Access historical data using HTTP, SFTP or web browser
Wide range of communication protocols Connect to existing DCS, PLC, DAQ and wireless interface
6km optical fiber = 6,000 points! Cost effective way of measuring temperature compared to traditional sensor technology

* Assuming appropriate scan rate and data refresh intervals are used

Oil & Gas

The development of unconventional resources, such as heavy oil, oil sands and shale gas has been progressing in line with the increase in global energy demand. DTSX200 can measure the temperature distribution along an optical fiber with a length of several kilometers are being applied to extraction of unconventional resources. DTSX200 maximizes oil/gas extraction by providing real time continuous temperature measurement through different injection dynamics. In addition to well optimization, DTSX200 provides critical data that help monitor and detect wellbore conditions for leaks, water penetration and gas breakthrough. DTSX200 also provides control capability (measurement of flow, pressure, temperature, valve position, etc.) on top of fiber optic temperature measurement. More importantly, compared to conventional wellbore monitoring technology, DTSX200 is more robust, cost effective and accurate.

Features Benefits
Ultra low power consumption: 10W Perfect for solar application in remote areas
Operating temperature range: -40 °C to 65 °C Perfect for rugged environment without cooling or heating
Fiber optic cable sensor Provides a complete and continuous profile of the downhole well
Control capability with NFCP050 module Monitor and control external devices such as flow, pressure, valve position, temperature, etc.
Wide range of communication protocols Connect to existing DCS, PLC, DAQ and wireless interface
6km optical fiber = 6,000 points! Cost effective way of measuring temperature compared to traditional sensor technology

Oil & Gas application image1Oil & Gas application image2



What if you could detect signs of abnormalities in bus ducts (bus bars) quickly during maintenance and inspection work and respond to them at just the right time? Yokogawa DTSX monitoring solution constantly monitors connections that tend to deteriorate over time and contributes by pinpointing abnormality locations and reducing workload of maintenance personnel, helping to ensure stability in plant operations.


Smart Monitoring of Manufacturing Process Shelves and Storage Shelves (In-vehicle Lithium-ion Battery Applications)


A belt conveyor fire detection solution employing the DTSX distributed optical fiber temperature sensor can greatly reduce crises that can threaten a company's survival.


Prevention of Fires in Exhaust Air Ducts in Battery Assembly Process (In-vehicle Lithium-ion Battery Applications)

Application Note

Temperature Monitoring Solution for 
Quick Detection of Fires in Fume Ducts


With industrial and economic development comes increasingly large and advanced power plants and factories. Nevertheless, we find many cases where the original cables, cable tunnels, and other components of the power infrastructure have languished under continuous operation.


Monitoring of Separator/Electrode Drying Furnace Temperature Distribution (In-vehicle Lithium-ion Battery Applications)


Reactor/Furnace Wall Healthiness Monitoring with a Fiber Optical Temperature Sensor

Application Note

Temperature Monitoring Solution for Maximum VSD Operating Efficiency


Recently, several ARC Advisory Group analysts and management team members had a chance to sit down with the new Yokogawa President and COO, Mr. Takashi Nishijima, and several other top Yokogawa executives to discuss the company's burgeoning presence in the worldwide upstream and midstream oil & gas industry.

Yokogawa Technical Report

The development of difficult to recover unconventional energy resources, is progressing. Figure 1 shows an example of how unconventional heavy oil is extracted from tar sand by reducing its viscosity with steam. To ensure efficient mining, changes in the underground temperature distribution will need to be monitored.



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