Sensors have an important role in the data logging process. All physical properties can be measured with sensors such as light, heat, sound, pressure, acidity and humidity.
The 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.
Sometimes it is necessary to record data 'out in the field'. This is called remote data logging. Readings are stored and brought back to a computer where they are downloaded and analysed. The equipment in these situations needs to be very robust - equipment used to monitor water levels would have to be waterproof; similarly equipment working in a satellite would have to be able to withstand vibration during launch and recovery.