interfaces connect to computers and can have sensors plugged into
them. They convert the readings which they derive from the sensors
into data which the computer can use. They convert continuous
variable signals from the sensors to numbers using a circuit called
an analogue-to-digital converter. These numbers are converted into
real values and displayed by a computer programme. Some data-logging
interfaces - called dataloggers - have their own memory and power
supply and can record data without an attached computer.
A datalogger is a self-contained serial port interface which has
its own power supply and memory to allow it to collect and store
data over time. It can be connected to different types of computers
to transfer data and instructions.
Some dataloggers must be programmed from the computer with specific
instructions about what and when to record, and are then disconnected
from the computer to carry them out. Dataloggers can be activated by the
press of a button and begin recording with whatever sensors are
plugged in, continuing to do so until they are deactivated. Some
have small display screens to display data in graphical form as
it is collected, a feature which enables students to see what is
happening (and to reassure them that the device is working!). Some
dataloggers can hold more than one set of data in memory at the
same time and all can transfer their data to a host computer for
Battery life can be a problem. Dataloggers can be programmed to
record data for weeks - as long as the batteries last (half as long
as the manufacturers claim is a good rule of thumb). Use a mains
power supply adaptor, if you can, to ensure that you'll have some
data worth analysing after a long recording.
Predictably, the more features a datalogger has, the more it costs.
It is worth considering whether you have a real need for all the
advanced features of an expensive datalogger compared with a mid-priced
serial data-logging interface.