In Monitoring application, we use sensor to collect data and microprocessor to record the data
Data maybe stored and output in various format
Monitoring application does not involve to control the environment. E.g. Temperature monitoring in weather station.
Control Application
Similar to monitoring application, but this time, actuators are used to CONTROL the environment that is monitoring.
Microprocessor will try to maintain the environment with the actuator to a preset value.
Example control application
Consider an electric heater, which can warm up a room to maintain a certain temperature
Sensor: Temperature sensor
Actuator: Heater / Heating element
Preset value: The desire temperature, to be inputted by the user
What is the microprocessor involved in the heater?
The temperature sensor is used to measure the temperature of the surrounding of the heater
Temperature data is sent to the microprocessor (through ADC)
Preset (desired) temperature is inputted by user (buttons/keypad)
Microprocessor compares the temperature from sensor with the Preset value. There will be two possibilities:
Preset < = surrounding (i.e. The environment is warmer than desired). Microprocessor will keep the heating element off.
Preset > surrounding (i.e. Too cold). Microprocessor will instruct the actuator (heating element) to turn on.
The whole process will repeat until power off
Temperature sensor
Microprocessor
Heating element
Temperature input panel
temperature
Preset value
feedback
Turn on if preset > temperature,
Turn off if preset < temperature
Note: ADC/DAC is omitted
Feedback
The feedback is there because the output from the heating element will affect what the sensor is reading.
Imagine if the heating element is turned on, a while later the sensor reading should increase because of that.
We put dotted line because the feedback is not direct connected. i.e. It is not the heating element directly changing the value of sensor, but indirectly through its action.