Data logger
Encyclopedia
A data logger is an electronic device that records data over time or in relation to location either with a built in instrument
or sensor
or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with a personal computer and utilize software to activate the data logger and view and analyze the collected data, while others have a local interface device (keypad, LCD) and can be used as a stand-alone device.
Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment or application type only. It is common for general purpose types to be programmable
; however, many remain as static machines with only a limited number or no changeable parameters. Electronic dataloggers have replaced chart recorder
s in many applications.
One of the primary benefits of using data loggers is the ability to automatically collect data on a 24-hour basis. Upon activation, data loggers are typically deployed and left unattended to measure and record information for the duration of the monitoring period. This allows for a comprehensive, accurate picture of the environmental conditions being monitored, such as air temperature and relative humidity.
The cost of data loggers has been declining over the years as technology improves and costs are reduced. Simple single channel data loggers cost as little as $25. More complicated loggers may costs hundreds or thousands of dollars.
is increasingly being adopted for data exchange. The development of the Semantic Web
is likely to accelerate this trend.
, that allows some instrumentation to be connected to a variety of data loggers. The use of this standard has not gained much acceptance outside the environmental industry. SDI-12 also supports multi drop instruments. Some datalogging companies are also now supporting the MODBUS
standard. This has been used traditionally in the industrial control area, and there are many industrial instruments which support this communication standard. Another multi drop protocol which is now starting to become more widely used is based upon Canbus (ISO 11898). Some data loggers utilize a flexible scripting environment to adapt themselves to various non-standard protocols.
are often used interchangeably. However, in a historical context they are quite different. A data logger is a data acquisition system, but a data acquisition system is not necessarily a data logger.
their alarms and FTP
their daily results into databases or direct to the users.
Scientific instrument
A scientific instrument can be any type of equipment, machine, apparatus or device as is specifically designed, constructed and often, through trial and error, ingeniously refined to apply utmost efficiency in the utilization of well proven physical principle, relationship or technology to...
or sensor
Sensor
A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated...
or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor (or computer). They generally are small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage, and sensors. Some data loggers interface with a personal computer and utilize software to activate the data logger and view and analyze the collected data, while others have a local interface device (keypad, LCD) and can be used as a stand-alone device.
Data loggers vary between general purpose types for a range of measurement applications to very specific devices for measuring in one environment or application type only. It is common for general purpose types to be programmable
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
; however, many remain as static machines with only a limited number or no changeable parameters. Electronic dataloggers have replaced chart recorder
Chart recorder
A chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper . Chart recorders may record several inputs using different color pens and may record onto strip charts or circular charts...
s in many applications.
One of the primary benefits of using data loggers is the ability to automatically collect data on a 24-hour basis. Upon activation, data loggers are typically deployed and left unattended to measure and record information for the duration of the monitoring period. This allows for a comprehensive, accurate picture of the environmental conditions being monitored, such as air temperature and relative humidity.
The cost of data loggers has been declining over the years as technology improves and costs are reduced. Simple single channel data loggers cost as little as $25. More complicated loggers may costs hundreds or thousands of dollars.
Data formats
Standardisation of protocols and data formats has been a problem but is now growing in the industry and XMLXML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
is increasingly being adopted for data exchange. The development of the Semantic Web
Semantic Web
The Semantic Web is a collaborative movement led by the World Wide Web Consortium that promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a "web of...
is likely to accelerate this trend.
Instrumentation protocols
Several protocols have been standardised including a smart protocol, SDI-12SDI-12
SDI-12 is the acronym for "Serial Data Interface at 1200 Baud". SDI-12 is an asynchronous, ASCII, serial communications protocol that was developed for intelligent sensory instruments that typically monitor environmental data...
, that allows some instrumentation to be connected to a variety of data loggers. The use of this standard has not gained much acceptance outside the environmental industry. SDI-12 also supports multi drop instruments. Some datalogging companies are also now supporting the MODBUS
Modbus
Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers . Simple and robust, it has since become one of the de facto standard communications protocols in the industry, and it is now amongst the most commonly available means of...
standard. This has been used traditionally in the industrial control area, and there are many industrial instruments which support this communication standard. Another multi drop protocol which is now starting to become more widely used is based upon Canbus (ISO 11898). Some data loggers utilize a flexible scripting environment to adapt themselves to various non-standard protocols.
Data logging versus data acquisition
The terms data logging and data acquisitionData acquisition
Data acquisition is the process of sampling signals that measure real world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems typically convert analog waveforms into digital values for processing...
are often used interchangeably. However, in a historical context they are quite different. A data logger is a data acquisition system, but a data acquisition system is not necessarily a data logger.
- Data loggers typically have slower sample rates. A maximum sample rate of 1 HzHertzThe hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
may be considered to be very fast for a data logger, yet very slow for a typical data acquisition system.
- Data loggers are implicitly stand-alone devices, while typical data acquisition system must remain tethered to a computer to acquire data. This stand-alone aspect of data loggers implies on-board memory that is used to store acquired data. Sometimes this memory is very large to accommodate many days, or even months, of unattended recording. This memory may be battery-backed static random access memoryStatic random access memoryStatic random-access memory is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM , it does not need to be periodically refreshed, as SRAM uses bistable latching circuitry to store each bit...
, flash memoryFlash memoryFlash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
or EEPROMEEPROMEEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non-volatile memory used in computers and other electronic devices to store small amounts of data that must be saved when power is removed, e.g., calibration...
. Earlier data loggers used magnetic tapeMagnetic tapeMagnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
, punched paper tape, or directly viewable records such as "strip chart recorderChart recorderA chart recorder is an electromechanical device that records an electrical or mechanical input trend onto a piece of paper . Chart recorders may record several inputs using different color pens and may record onto strip charts or circular charts...
s".
- Given the extended recording times of data loggers, they typically feature a mechanism to record the date and time in a timestampTimestampA timestamp is a sequence of characters, denoting the date or time at which a certain event occurred. A timestamp is the time at which an event is recorded by a computer, not the time of the event itself...
to ensure that each recorded data value is associated with a date and time of acquisition in order to produce a sequence of events. As such, data loggers typically employ built-in real-time clockReal-time clockA real-time clock is a computer clock that keeps track of the current time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in almost any electronic device which needs to keep accurate time.-Terminology:The term is used to avoid...
s whose published drift can be an important consideration when choosing between data loggers.
- Data loggers range from simple single-channel input to complex multi-channel instruments. Typically, the simpler the device the less programming flexibility. Some more sophisticated instruments allow for cross-channel computations and alarms based on predetermined conditions. The newest of data loggers can serve web pages, allowing numerous people to monitor a system remotely.
- The unattended and remote nature of many data logger applications implies the need in some applications to operate from a DCDirect currentDirect current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...
power source, such as a batteryBattery (electricity)An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
. Solar power may be used to supplement these power sources. These constraints have generally led to ensure that the devices they market are extremely power efficient relative to computers. In many cases they are required to operate in harsh environmental conditions where computers will not function reliably.
- This unattended nature also dictates that data loggers must be extremely reliable. Since they may operate for long periods nonstop with little or no human supervision, and may be installed in harsh or remote locations, it is imperative that so long as they have power, they will not fail to log data for any reason. Manufacturers go to great length to ensure that the devices can be depended on in these applications. As such dataloggers are almost completely immune to the problems that might affect a general-purpose computer in the same application, such as program crashes and the instability of some operating systems.
Applications
Applications of data logging include:- Unattended weather stationWeather stationA weather station is a facility, either on land or sea, with instruments and equipment for observing atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, barometric pressure, humidity, wind speed, wind...
recording (such as wind speedWind speedWind speed, or wind velocity, is a fundamental atmospheric rate.Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth and metabolism rate of many plant species, and countless other implications....
/ direction, temperatureTemperatureTemperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
, relative humidityRelative humidityRelative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
, solar radiation). - Unattended hydrographic recording (such as water level, water depth, water flow, water pH, water conductivity).
- Unattended soil moisture level recording.
- Unattended gas pressure recording.
- Offshore buoys for recording a variety of environmental conditions.
- Road traffic counting.
- Measure temperatureTemperatureTemperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s (humidity, etc) of perishables during shipments: Cold chainCold chainA cold chain is a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range...
. - Process monitoring for maintenance and troubleshooting applications.
- Process monitoring to verify warranty conditions
- Wildlife research with pop-up archival tagsPop-up satellite archival tagPop-up satellite archival tags are used to track movements of marine animals. A PSAT is an archival tag that is equipped with a means to transmit the data via satellite...
- Measure vibrationVibrationVibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
and handling shockShock (mechanics)A mechanical or physical shock is a sudden acceleration or deceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation....
(drop height) environment of distribution packaging. - Tank level monitoring.
- Deformation monitoringDeformation monitoringDeformation monitoring is the systematic measurement and tracking of the alteration in the shape or dimensions of an object as a result of stresses induced by applied loads...
of any object with geodetic or geotechnical sensors controlled by an automatic deformation monitoring systemAutomatic Deformation Monitoring SystemAn automatic deformation monitoring system is a group of interacting, interrelated, or interdependent software and hardware elements forming a complex whole for deformation monitoring that, once set up, does not require human input to function. Automatic deformation monitoring systems provide a...
. - Environmental monitoringEnvironmental monitoringEnvironmental monitoring describes the processes and activities that need to take place to characterise and monitor the quality of the environment...
. - Vehicle Testing (including crash testing)
- Motor Racing
- Monitoring of relay status in railway signalling.
- For science education enabling 'measurement', 'scientific investigation' and an appreciation of 'change'
- Record trend data at regular intervals in veterinary vital signs monitoring.
- Load profileLoad profileIn electrical engineering, a load profile is a graph of the variation in the electrical load versus time. A load profile will vary according to customer type , temperature and holiday seasons....
recording for energy consumption management. - Temperature, Humidity and Power use for Heating and Air conditioning efficiency studies.
- Water level monitoring for groundwater studies.
Future directions
Data Loggers are changing more rapidly now than ever before. The original model of a stand alone data logger is changing to one of a device that collects data but also has access to wireless communications for alarming of events, automatic reporting of data and remote control. Dataloggers are beginning to serve web pages for current readings, e-mailE-mail
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
their alarms and FTP
File Transfer Protocol
File Transfer Protocol is a standard network protocol used to transfer files from one host to another host over a TCP-based network, such as the Internet. FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server...
their daily results into databases or direct to the users.
Examples
- A flight data recorderFlight data recorderA flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
(FDR), a piece of recording equipment used to collect specific aircraft performance data. The term may also be used, albeit less accurately, to describe the cockpit voice recorderCockpit voice recorderA cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
(CVR), another type of data recording device found onboard aircraft. - An event data recorderEvent Data RecorderAn event data recorder or EDR is a device installed in some automobiles to record information related to vehicle crashes or accidents. In modern diesel trucks, EDRs are triggered by electronically sensed problems in the engine , or a sudden change in wheel speed. One or more of these conditions...
(EDR), a device installed by the manufacturer in some automobileAutomobileAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s which collects and stores various data during the timeframe immediately before and after a crash. - A voyage data recorderVoyage Data Recorderthumb|A fixed Data Capsule of VDR mounted on a [[container ship]].Voyage Data Recorder, or VDR, is a data recording system designed for all vessels required to comply with the IMO's International Convention SOLAS Requirements in order to collect data from various sensors on board the vessel...
(VDR), a data recording system designed to collect data from various sensors on board a ship. - Ultra Wideband Data Recorder, high-speed data recording up to 2 GigaSamples per second.
- The growing, preparation, storage and transportation of food. Data logger is generally used for data storage and these are small in size.
- In automobiles, all diagnostic trouble codes (DTCs) are logged in engine control unitEngine control unitAn engine control unit is a type of electronic control unit that determines the amount of fuel, ignition timing and other parameters an internal combustion engine needs to keep running...
s (ECUs) so that at the time of service of a vehicle, a service engineer will read all the DTCs using Tech-II or similar tools and will come to know problems occurred in the vehicle. - In the racing industry, Data Loggers are used to record data such as braking points, lap/sector timing, and track maps etc. A product produced by Race Technology capable of doing this is the DL1 Data logger and can be used on any type of vehicle. There are also other alternative products available on the market.
See also
- Black boxBlack Box (transportation)The term black box is a placeholder name used casually to refer to a collection of several different recording devices used in transportation: the flight recorders in aircraft, the event recorder in railway locomotives, the event data recorder in automobiles, message case in ships, and other...
- Flight recorderFlight recorderA flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of an aircraft accident or incident. For this reason, flight recorders are required to be capable of surviving the conditions likely to be encountered in a severe aircraft...
- Common Log FormatCommon Log FormatThe Common Log Format is a standardised text file format used by web servers when generating log files. Because the format is standardised, the files may be analysed by a variety of analysis programs....
- Continuous emissions monitoring systemContinuous emissions monitoring systemCEM systems were historically used as a tool to monitor flue gas for oxygen, carbon monoxide, and carbon dioxide to provide information for combustion control in industrial settings...
- Digital traces
- Java Logging FrameworksJava Logging FrameworksA Java logging framework is a computer data logging package for the Java platform.In software, logging refers to the recording of activity. Logging is a common issue for development teams. Several frameworks ease and standardize the process of logging for the Java platform...
- logging frameworks for JavaJava (programming language)Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities... - List of web analytics software
- Log management and intelligenceLog management and intelligenceLog management comprises an approach to dealing with large volumes of computer-generated log messages...
- MultiTailMultitailMultiTail is a program for monitoring multiple log files, in the fashion of the original tail program. The original tail presents the last few lines of a single log file, optionally providing a real-time display of the growing file....
- tool for watching logging (for UNIXUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
) - PantheiosPantheiosPantheios is an open source C/C++ logging API library, whose design focus is performance, robustness and transparency. It claims 100% type-safety, and high efficiency....
logging API library - Runtime intelligenceRuntime intelligence-Introduction:The term runtime intelligence refers to technologies, managed services and practices for the collection, integration, analysis, and presentation of application usage levels, patterns and practices...
- Sequence of events recorderSequence of events recorderA sequence of events recorder is an intelligent standalone microprocessor based system, which monitors external inputs and records the time and sequence of the changes. Sequence of events recorders usually have an external time source such as a GPS or radio clock...
- Server logServer logA server log is a log file automatically created and maintained by a server of activity performed by it.A typical example is a web server log which maintains a history of page requests. The W3C maintains a standard format for web server log files, but other proprietary formats exist...
- SyslogSyslogSyslog is a standard for computer data logging. It allows separation of the software that generates messages from the system that stores them and the software that reports and analyzes them...
- Web counterWeb counterA web counter or hit counter is a computer software program that indicates the number of visitors, or hits, a particular webpage has received...
- Web log analysis softwareWeb log analysis softwareWeb log analysis software is a simple kind of Web analytics software that parses a log file from a web server, and based on the values contained in the log file, derives indicators about who, when, and how a web server is visited...