Dataloggers

? Continuous measurement of any variable requires some sort of logging device- a datalogger. The first data recorders converted the measured electrical signal into the movement of a pen onto a continuously moving rol...

? Continuous measurement of any variable requires some sort of logging device-

a datalogger.

The first data recorders converted the measured electrical signal into the movement of a pen onto a continuously moving roll of paper.

Paper records of this type have the advantage of being relatively permanent (as long as paper or ink didn't run out). However, any further electronic processing required this data to be read off and entered - leaving plenty of room for error.

Electronic storage of the data was therefore an obvious next step once this technology matured, and has now become so cost effective that vast amounts of data can now be stored.

The simplest dataloggers merely collect data and are not capable of any mathematical conversion of the data collected. More advanced loggers can be programmed to calculate averages or other statistical functions of the data, thereby reducing the amount that needs to be stored and increasing the time required before the data must be collected.

Dataloggers are either custom made to suit particular sensor/s, but are increasingly becoming standardised so that they may be used with any sensor that outputs a standard voltage. This is typically 0 to 20 mV.

Programmable dataloggers and those for use with a PC are listed on this page.

A programmable logger is one with electronics that allows more control over data collection, and more advanced data processing prior to storage. This in turn allows greater control over what and when sensors are polled.

Most programmable loggers are designed to be used with a PC, if required for, data storage or online viewing.

There are models that have to be installed in a PC, or connected to a PC (or other computer) to operate. These take advantage of the power of the computer, and allow a standardised setup is possbile. On the downside, the PC must be usually situated close to the sensors, and although it can be used for other functions, it needs to be fairly dedicated to the job. Often an older computer can be pressed back into service for thses types of jobs, but the modern software most likely will require an adequate processor, if realtime processing is done.

The type of measuring application determines the type of datalogging device chosen.

Paper-based: the original method of recording data, fan paper, drum or circular.
Some applications still suit a paper and pen based recorder, but most data is required electronically for further processing, storage and transport. Whilst electronic data is easily and inexepensively stored and transferred, it also stands a chance of being accidentally lost. Paper-based records, on the other hand are less volatile in the short term, must be digitised before they can be processed.

Electronic loggers may be dedicated to a particular sensor, measurement type, or can be programmed to measure in various modes and perform statistical functions on the data whilst still in the logger to reduce the amount that needs to be stored.

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