1. Input-Output-Process Demo
Central Heating System
24/02/2019

2. User sets the desired temperature.
Input
Processor
Preset Value:
User sets the desired temperature.
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3. Input - Measurement Processor
The monitoring of physical variables without the microprocessor taking action.
Temperature readings
Temperature Sensor
Processor
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4. Compares current temperature with preset value
Processing
Processor
Compares current temperature with preset value
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5. If current temperature < preset value
When a microprocessor takes action depending on sensor readings.
Processing Control
Too cold
Signal
Heater On
Processor
If current temperature < preset value
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6. Output
Too cold
Heater On
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7. If current temperature > preset value
When a microprocessor takes action depending on sensor readings.
Processing Control
Too Hot
Processor
If current temperature > preset value
Signal
Heater Off
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8. The process is continuous and so repeats.
Output
Too Hot
Heater Off
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The process is continuous and so repeats.

9. Notes: Input: Processing: Output:
User sets the desired preset value.
Sensors sending readings.
Processing:
Microprocessor comparing the preset value with the current sensor readings.
If higher / lower then microprocessor decides to switch a device on / off.
Output:
Devices actually being switched on or off.
Sensors do not compare or decide to switch anything on or off, they only send current readings.
24/02/2019