Need help on this! A real time system is a system whose specification includes b

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A real time system is a system whose specification includes both logical and temporal correctness requirements. Consider an Elevator Control System in which customer uses push buttons to do appropriate actions. The system keeps idle till it receives input or signal from the user. Initially user can give input via pushbutton like upward or downward. And later the system can do appropriate tasks up on receiving the inputs available in the system. Identify all the real time requirements of the Elevator Control System and classify the real time system based on its specification requirements. Also discuss a scheduling algorithm which is suitable for this system and justify it.

Explanation / Answer

The elevator control system has a some real time requirements and these can basically be expalined below:

1- Inputs, which include:

A- Sensors.
B- Buttons.
C- Key controls.
D- System controls.

A) sensor includes Magnetic sensor and weight loading sensors

B) buttton includes hall buttons,floor required button and open door butons,emergency stopbutton and emergency bell buttons

c) Key controls:Key controls may only be activated by the proper keys, and their use is thus restricted to repair people, elevator operators or firemen. It is used in place of or in conjunction with a pushbutton to restrict access to a floor. Keypads and card readers are also available

d)System Controls:System controls are used to turn the elevator system on or off, system controls are only accessible from an elevator control room. They would typically be used quite infrequently – perhaps the system would be turned on early in the morning and turned off late at night, or turned off at the start of holidays and turned on once the next term begins.

2- Outputs, which include:

A- Actuators.
B- Bells.
C- Displays.

A) Aculators contains door opening device ,electrinc motor and Brakes

B)bells are two types Emergency bell and loading bell

C) Dispaly means it shows Position display of the elevator and direciton display for up and down

3- Controller

The controller is a device which manages the visual monitoring, interactive command control and traffic analysis system to ensure the elevators are functioning efficiently.

In disk shcheduling alogirthms Scan algorithm is best for the elevator control system because, It scans down towards the nearest end and then when it hits the bottom it scans up servicing the requests that it didn't get going down. If a request comes in after it has been scanned it will not be serviced until the process comes back down or moves back up. This process moved a total of 230 tracks. Once again this is more optimal than the previous algorithm.

Thank You!

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