Data LoggingMehnaaz Asad

IB2-3

Data logging is the collection of data over a period of time, and is something often used in scientific experiments. Data logging systems

typically monitor a process using sensors linked to a computer. Most data logging can be done

automatically under computer control.

What is data logging?

IT System: Hardware•Sensors

•Data-logger is a basic box capable of picking up and storing signals from sensors.

•Computer

Normally, the sensors are plugged into the data-logger circuit box which in turn is connected to the computer. Optionally, a printer is also useful for printing out graphs on paper.

IT System: SoftwareThe common functions of a data-logging program are as follows:

Take readings from the sensors at regular intervals. It is possible to take many readings at time intervals ranging from a few microseconds to hours or even days.

Present the data in a suitable form of display on the screen.The graph plotting facility is particularly useful since the computer can generate them very quickly allowing the software to compare several sets of results.Also, the program provides aids for accurately analysing the results and performing calculations on the data.

Print the data table or graph on paper using a printer connected to the computer.

Store the data on a computer disc for future use.

Different types of data loggingContinuous recordingThe rapid repetition of measurements (hundreds of values per second)

Simultaneous recordingMeasurements from several sensors may be collected simultaneously.

Period loggingData may be collected over a period of hours or days.

Remote Logging

Data may be collected independently from the computer using a data- logger. Data logger may be sited in locations which are not convenient for computers.This is well-suited to longer term experiments.

DelayA data logger may be set up so that it waits for a specified time before beginning to log data.

ProcessThe sensors send signals to an interface box,

which is linked to a computer. The interface box converts analogue signals to digital signals that the computer can understand.

The computer controlling the process will take readings at regular intervals. The time interval for data logging is the time between readings. The logging period is the total length of time over which readings are taken.

The readings are stored in tables and can be displayed in graphs or passed to an application, such as a spreadsheet, for later analysis.

Example 1

The following describes an experiment to determine the rate at which water cools down from boiling point:A temperature sensor is placed in the liquid.The sensor is connected to an interface box linked to the computer.The data logging software is set to take readings every 30 seconds (time interval) for 25 minutes (logging period).

Interpretation

The data logging software will typically store the readings in a table. The data can later be analysed using graph tools.A graph which could be used in this experiment is a cooling curve graph.

Other examples•How much light would a leaf get? (light sensors)•Best thermal insulators? (temperature sensors)•What material is most sound proof? (sound sensors)•What are the best atmospheric conditions for a greenhouse? (combination of sensors)

PROSImproves the accuracyCollects information from scientific experiments

and monitoring systems faster than humansDisplays the results in a graphical formPrints out and analyses the resultsEase of use / display on a screen / drafts and

analysis of the results.Remote logging enables to calculate the

experiments from remote locations that are inaccessible by humans and many computers.

CONSStoring data logging systems in the databases

is very complex and hard to manageIt is hard to implement the data logging

system.Software has to be designed properly, in order

to work with the hardware.High performance computers are needed in

order to analyse the data.

Social and Ethical Issues

People and Machines: We are becoming too dependent on the technology and, if necessary, might not be able to perform the actual experiment that confidently.

Equality of Access: Those who don’t have access to this technology lose out and have to record data manually.

Integrity: The data entered has to be correct and accurate, or else it raises the issue of reliability as well.

Health: You don’t have to come in direct contact with any harmful chemicals while recording the data.You can monitor from a safe distance.

SOURCEShttp://www.ruthtrumpold.id.au/itgswiki/pmwiki.php?n=DataLogging.DataLogging

http://www.ncte.ie/documents/advicesheets/32DataloggingNov08.pdf

http://www.bbc.co.uk/schools/gcsebitesize/ict/measurecontrol/3dataloggingrev1.shtml

http://www.hitchams.suffolk.sch.uk/datalogging/examples.htm

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