Topic 5: Data Logging& Sensors

Topic 5: Data Logging& Sensors

1. Data Logging

   • Data logging involves collecting dat automatically from sensors over a certain period of time.
   • Main features
     • The readings are taken automatically which means there is no need for a human to be present.
     • You can set the logging period (the total time ver which the readings will be collected)
     • You can set the logging rate which determines how often the readings are taken.
     • The sensors can be put in remote locations.
     • The sent data can be stored and processed by a computer.
     • The data can be analysed and graphs and charts can be drawn.
   • Advantages
     • Data collection can be automatic so no human presence is necessary.
     • Readings can be continually taken over time.
     • There is no chance of somebody forgetting to take a reading.
     • Readings will be more accurate as there is no chance of human error.
     • Sensors can be placed in locations where it is dangerous for humans to go.
     • Readings can be taken very quickly which no human could achieve.
   • Disadvantages
     • If there is a fault it could go unnoticed for a long time.
     • Some equipment can be expensive.

2. Types of sensors

   • Temperature Sensors
     • Measure temperature.
     • Can be used in school experiments and to control a heating system at school or in a classroom.
   • Light Sensors
     • Detect the brightness of light.
     • Can be used to see how light levels affect the growth of plants or to control lights that come on automatically when it goes dark.
   • Sound Sensors
     • Measure the loudness of a sound.
     • Can be used in noise disputes.
   • Pressure Sensors
     • Barometric pressure sensors measure air pressure.
     • Other pressure sensors measure depth of liquid or something which is pressing on them.
     • Can be used for automatic doors and burglar alarm systems.
   • Humidity Sensors
     • Measure water vapour in the air.
     • Can be used in swimming pools and greenhouses.
   • Passive Infrared Sensors (PIRs)
     • Detect movement and infrared radiation.
     • Can be used in burglar alarms and also to turn lights on/off when a person enters/leaves a room.

3. Computer Data Logging Systems

   • Advantages
     • Readings can be more accurate than those taken by humans.
     • Readings can be taken in dangerous or hazardous places.
     • Readings can be taken at very short intervals.
     • Readings can be read 24/7 without a break.
     • Error free.
   • Disadvantages
     • Computers can not easily respond to changing circumstances.
     • Data loggers will only log what they are programmed to log.

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