PLC examples

PLC examples

prob.1: Write a plc program to start & stop a motor using one input. sol.: One input means one button     X=1 button is pressed. X=0 button is not pressed. Truth Table X Y 0 0 1 1 prob.2: A motor operated with a push button. sol.:  (Bush Button)   stop X1=1 start button is pressed X1=0 start button is not pressed X2=1 stop button is pressed X2=0 stop button is not pressed     (AND)  (OR)   (output)  Truth Table: X1 Y(old) X2 Y(new) 0 0 0 0 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 0 1 1 0 1 1 1 1 0 X2 (AND)      Prpb.3: We have machine will turn on if we bush two buttons. Construct the ladder diagram and write truth table. X1=1 button 1 is pressed. X1=0 button 1 is not pressed. X2=1 button 2 is pressed. X2=1 button 2 is not pressed. Truth table X1(Button 1) X2(Button2) Machine 0 0 0 0 1 0 1 0 0 1 1 1 Prob.4:(final 2008 3-c): A car door, seatbelt system. When the car door is open, or the seatbelt is not done up, the ignition power must not be applied. if all is safe then the key will start the engine.  X1=1 car door is closed X1=0 car door is open X2=1 seatbelt is closed X2=0 seatbelt is open X1 X2 Machine 0 0 0 0 1 0 1 0 0 1 1 1 prop.5:(final 2008 3-a): Will cause output D to be on when push button A is on, or either B or C are on.   A or B or C. A=1 button A is pressed. A=0 button A is not pressed. B=1 button B is pressed. B=0 button B is not pressed. C=1 button C is pressed. C=0 button C is not pressed. A B C Y 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 1  238   2 1  Prob.6:(final 2008 3-b): -So that three switches in a room could turn the light on or of.     Sol.:  (Truth Table)  A=1 button A is pressed. A=0 button A is not pressed. B=1 button B is pressed. B=0 button B is not pressed. C=1 button C is pressed. C=0 button C is not pressed. Truth Table A B C Y 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 1       (ladder diagram)   Y= ABC + ABC + ABC + ABC A: mean that A=0. Ladder Diagram:               (OR)  Prob.7:(final 2007 5): An emergency system is to be designed for a certain production machine. A single "start" button is used to turn on the power to the machine at the beginning of the day, In addition, there are three "stop" buttons located at different locations around the machine, any one is of which can be passed to immediately turn off the machine.  Write the truth table for this system.  Construct the ladder logic diagram for the system. Sol.: Start=1 button start is pressed. Start=0 button start is not pressed. Stop1=1 button stop1 is pressed. Stop1=0 button stop1 is not pressed. Stop2=1 button stop2 is pressed. Stop2=0 button stop2 is not pressed. Stop3=1 button stop3 is pressed. Stop3=0 button stop3 is not pressed. Truth Table:    Start Stop1 Stop2 Stop3 Machine 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 1 0 0 1 1 0 0 0 1 1 1 0 1 0 0 0 1 1 0 0 1 0 1 0 1 0 0 1 0 1 1 0 1 1 0 0 0 1 1 0 1 0 1 1 1 0 0 1 1 1 1 0 Ladder Diagram Prob.8:  (ladder diagram)  C1 (relay)  S1 (solenoid)   Fs (Float Switch)  Fs  C2 (relay)  C2  T1 (timer)    T1   S2 (solenoid)  T1  T2   T1.