Question 2: Answer all parts Consider the task of semi automating the drilling of a work...

Transcribed Image Text:

Question 2: Answer all parts Consider the task of semi automating the drilling of a work piece, as depicted in Figure Q2. The system, which contains pneumatic cylinders and valves, a compressor and an electric drill motor, is to be controlled by a Programmable Logic Controller (PLC). Control Description: The drill motor and a compressor for the air pressure for the pneumatic valves have to be started by means of a start button. Cycle: o The work piece has then to be clamped. o The drill has then to be lowered until the required depth is achieved by activation of limit switch 2. o Then the drill has to be retracted and the work piece unclamped. Each cylinders position is to be interrogated by means of two limit switches as depicted. The sequence above should run one whole cycle, even if the stop button is depressed in mid cycle. The drill motor and a compressor should be switched off only after the cycle has completed. Solenoid 3 (Y2) izm Solenoid 1 (YO) Solenoid 2 (Y 1) AAAA Drill Cylinder Limit switch 3 (X4) Clamp Cylinder Limit switch 4 (X5) Figure Q2 Drill Motor (Y3) Dri Work piece Start (XO) Stop (X1) Limit switch 1 (X2) Limit switch 2 (X3) Compressor (Y4) Control Inputs: Start button (normally open-spring returned) (XO) Stop button (normally closed-spring returned) (X1) Limit switch 1 (normally open) Limit switch 2 (normally open) Limit switch 3 (normally open) Limit switch 4 (normally open) (X2) Control Outputs: Solenoid 1 (drill cylinder extend) Solenoid 2 (drill cylinder retract) Solenoid 3 (clamp cylinder extend/retract) Motor (contactor/relay for switching) Compressor (contactor/relay for switching) (X3) (X4) (X5) (YO) (Y1) (Y2) (Y3) (Y4) (a) Implement a commented ladder logic PLC program for the control solution, indicate any internal PLC locations you may use in your solution. (20 marks (5 marks (b) Explain your solution in detail. (c) Outline how you would modify the relevant sections of your code in (a) to implement the following. If the drill takes more than 2 seconds to reach the required depth this typically indicates that the drill bit is blunt and needs replacement. If this occurs the cycle should complete and then an additional output [Drill Bit Watchdog (Y5)] should flash to alert the user for drill bit replacement. Once the cycle is restarted this output should cease flashing. (5 marks Question 2: Answer all parts Consider the task of semi automating the drilling of a work piece, as depicted in Figure Q2. The system, which contains pneumatic cylinders and valves, a compressor and an electric drill motor, is to be controlled by a Programmable Logic Controller (PLC). Control Description: The drill motor and a compressor for the air pressure for the pneumatic valves have to be started by means of a start button. Cycle: o The work piece has then to be clamped. o The drill has then to be lowered until the required depth is achieved by activation of limit switch 2. o Then the drill has to be retracted and the work piece unclamped. Each cylinders position is to be interrogated by means of two limit switches as depicted. The sequence above should run one whole cycle, even if the stop button is depressed in mid cycle. The drill motor and a compressor should be switched off only after the cycle has completed. Solenoid 3 (Y2) izm Solenoid 1 (YO) Solenoid 2 (Y 1) AAAA Drill Cylinder Limit switch 3 (X4) Clamp Cylinder Limit switch 4 (X5) Figure Q2 Drill Motor (Y3) Dri Work piece Start (XO) Stop (X1) Limit switch 1 (X2) Limit switch 2 (X3) Compressor (Y4) Control Inputs: Start button (normally open-spring returned) (XO) Stop button (normally closed-spring returned) (X1) Limit switch 1 (normally open) Limit switch 2 (normally open) Limit switch 3 (normally open) Limit switch 4 (normally open) (X2) Control Outputs: Solenoid 1 (drill cylinder extend) Solenoid 2 (drill cylinder retract) Solenoid 3 (clamp cylinder extend/retract) Motor (contactor/relay for switching) Compressor (contactor/relay for switching) (X3) (X4) (X5) (YO) (Y1) (Y2) (Y3) (Y4) (a) Implement a commented ladder logic PLC program for the control solution, indicate any internal PLC locations you may use in your solution. (20 marks (5 marks (b) Explain your solution in detail. (c) Outline how you would modify the relevant sections of your code in (a) to implement the following. If the drill takes more than 2 seconds to reach the required depth this typically indicates that the drill bit is blunt and needs replacement. If this occurs the cycle should complete and then an additional output [Drill Bit Watchdog (Y5)] should flash to alert the user for drill bit replacement. Once the cycle is restarted this output should cease flashing. (5 marks