Interrupt handling
Process control
Overview | Online | Parallelism
- Through an analogue to digital converter the physical measurements are converted to
discrete numbers which are relayed to a computer for comparison with standards.
- If there is a difference, the computer decides what adjustments are necessary and sends
an appropriate command to a control mechanism in order to bring operations back to
standard.
![[Ref]](../../v2gr/v2gr_00/b_ref.gif) Ref
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On-line interactive
Round robin (Time slicing)
Controller rotates round sensors,
Interrupt: Sensor gives reading requiring some action, this suspends the normal
operation, while interrupt managed.
Controller proceeds on normal operation.
Switched
Explain how the following processes are controlled using the terms of the process
control cycle.
Oven
Thermostat (sensor) senses when temperature drops (process) then decides (control) to
turn on element (actuator).
Traffic lights
Roadpad (sensor) senses when a car goes over (process) then decides (control) to turn
facing light green other red (actuator).
Fuel injection
Fuel injection (sensor) realises when the car speed changes (process) then decides
(control) to decrease or increase petrol (actuator).
Parallelism
- Multiple processors handle individual sensors.
[Rev: 28/1/98] Jun-97 © 1997-98 V/2-Com (Verhaart), P O Box 8415,
Havelock North, New Zealand.