AS ICT Control Systems Objectives Have an understanding

AS ICT Control Systems

Objectives Have an understanding of how organizations use ICT. Be able to describe a number of uses, giving the hardware and software requirements. Be able to describe the applications that these uses can be put to.

What is a control system? Uses microprocessors or computers to control certain physical conditions, either Keeping them the same over a period of time or Varying them according to predefined values/lengths of time

Examples of control systems Maintaining constant physical conditions: Air conditioning systems Central heating systems Refrigeration Medical applications: Intensive care Car Manufacture plants Process Control

Physical conditions (variables) that are controlled by computer/microprocessors include: Temperature Pressure Humidity Light Moisture etc

Hardware requirements: Input Numeric Keypad Push buttons/switches Temperature sensor Moisture sensor Pressure sensor Light sensor Contact Switch

Hardware requirements: Process ADC DAC Timer Algorithms to compare data from sensors to predefined values or ranges

Hardware requirements: Output Robot Fans Heaters Boilers Buzzer/alarm Lights LED display

Air conditioning Sensors are needed to monitor temperature (continuously) Microprocessor compares the temperature with a preset value/range Depending on result microprocessor causes the fan motor to speed up or slow down Fan motor switched on or off

IPO/hardware requirements Inputs Processes Outputs Buttons/touchscreen Sensors monitor temperature continuously LED display Contact switch Analogue data from sensors converted to digital using ADC Fan Temperature sensor Temperature compared to preset range/value Buzzer Pressure sensor Signal sent to actuator to switch fan on or off

Closed Loop system Output directly affects the input No human intervention is necessary Good for situations where control is required 24/7, or in a dangerous/difficult environment

Refrigeration Sensors continuously monitor temperature Microprocessor compares the temperature with a preset value/range Depending on result microprocessor causes the fan motor to speed up or slow down Fan motor switched on or off

IPO/hardware requirements Inputs Processes Outputs Contact switch (door) Sensors monitor temperature continuously LED display Pressure sensor (door) Analogue data from temperature sensor converted to digital by ADC Compressor Number pad or dial Temperature compared to preset range/value input by user Buzzer Temperature sensor Signal sent to actuator to switch compressor on if temp is too high Signal sent to actuator to switch compressor off if temp is OK

Central heating Sensors are needed to monitor temperature (continuously) Microprocessor compares the temperature with a preset value/range Microprocessor controls two actuators one opens gas valves in the boiler the other switches the pump on

IPO/hardware requirements Inputs Processes Outputs Touch screen Sensors monitor temperature continuously LED display Number pad or dial Analogue data from temperature sensor converted to digital by ADC Radiators Temperature sensor Temperature compared to preset range/value input by user Signal sent to actuators to switch pump on & open valves if temp is too low Signal sent to actuator to switch pump off/close valves if temp is OK