1. Data Logging

2. Data logging uses the same basic equipment as computer control, you still need a sensor to take readings, you still need a computer that has been programmed to take the readings every so many seconds or minutes but this time we do not need to consider any form of output device.
We are simply going to take readings from the sensor and record them

3. Using our fish tank example:
Imagine that we are going to take readings of the temperature of the water.
The device used to take these readings is not a "thermometer" it is a "thermistor"
All we want to do is to record how hot or cold the water is at any given time, and keep a record of these readings over a couple of days.

4. How do we store the readings?
We need to set up a simple spreadsheet a bit like the one set out below:

5. Data Logging needs a Spreadsheet and not a database.
Remember:
Data Logging needs a Spreadsheet and not a database.

6. The whole point of data logging is that we can record data and then examine that data to see if there are any trends, it might mean that the readings show us that the tank is always going to be too cold and that the fish will die.

7. Graphing the results:
The reason for using graphs is really quite straightforward, they are easier to understand.

8. Data logging is only going to be useful if you can compare data and this is the key point about analysing data.
Sure it's great if you can record data but it is only going to be of use if you have something to judge it against.

9. More Examples:

10. Advantages:
One advantage of data logging is that it can be done in places that are hostile for humans such as inside a nuclear reactor or a volcano.
Data logging equipment therefore often has to be very robust so that it can resist extremes of temperature or radiation for example.

11. Another advantage of data logging is that regular data can be collected over very short or very long time periods that would be impossible or impractical for a human operator.
Example: data logging equipment can record hundreds of readings in less than a second. (Imagine asking a human to take 100 pressure readings inside a room as an explosion is set off) 

12. Examples of data logging in use:
In a hospital:
The sort of life support systems found in intensive care units will make extensive use of data logging equipment. The patients will have sensors attached to them which will continuously measure data such as temperature, blood oxygen level and heart rate.

13. Advantages:
24 hour monitoring takes place without having to use a human operator who would need breaks, could lose concentration or could get tired and make mistakes.
Alarms would be set off automatically if any measurements exceed a safe value.
A continual record can be stored or printed out of everything that is being measured.

14. Analogue to Digital - ADC
Many sensors produce analogue signals which must be converted to digital signals so they can work with computers.
An analogue to digital converter changes the varying voltage from the sensor into pulses which are the digital equivalent of the voltage value.

15. Summary: