PLC Ladder Diagram for Four-Floor Elevator

Functional specification:

• When an inside floor button is pressed
• Latch occupant inside priority
• Close the doors, move to that floor and open the doors.
• After a timeout, unlatch occupant inside priority
• When an outside floor button is pushed and there is no occupant priority
• Place that floor number into a call queue.
• Close the doors, move to that floor, open doors and wait.
• If no inside floor button is pressed within a timeout time
• close the doors, and move to the next floor in the call queue, open the doors and wait.
• When there is no floor number in the call queue and no occupant priority
• wait for an outside call button to be pressed.
• If no outside call button has been pressed within a timeout time.
• Close doors, return to the ground floor if morning or the top floor if afternoon (suggestion?), open doors and wait.

Something like that?

The next refinement would be to service floors that are in the call queue should the lift pass those floors.

Thanks for your reply

All functional specification you mentioned is ok,

I have badly struck in call queue....

how to write logic for call queue??????????????????

I shall be great full to you if you suggest on this.............

Thanks

This is intended only as a hint. _{I will not write your code without a fee.} Consider the elevator's state diagram, specifically the status of the elevator's direction lights and the status of each floor's call buttons.

This can be done on chargable basis,since manhours and knoledge on lift as well as plc is requird