PLC Assignments on Latching
Assignment 1:-
Draw the LAD logic for a latching circuit.
Assignment 2:-
Three conveyors are to be started and stopped in different sequences with help of two-three sets of push buttons each (One START/NO and One STOP/NC). Whenever it is required any conveyer can be started and stopped with this set of push buttons separately. When all the conveyors are running or any two is running it can be stopped only with an emergency stop.
(HINTS:-START-STOP).
Assignment 3:-
A conveyer ’C’ is to run when any of the four push buttons is pressed. The conveyor is to stop when any one of the four feedback comes to the plc from the physical site.
Assignment 4:-
Design and draw the schematic for a conventional hardwired circuit that will perform the following circuit functions using two break-make pushbuttons:
Turn in light L1 when push button PB1 is pressed.
Turn in light L2 when push button PB2 is pressed.
Electricity interlock the pushbutton so that L1 and L2 cannot both be turned on at the same time.
Assignment 5:-
In a meeting room, smoking is strictly prohibited. When a person smokes, there is a sensor to sense the smoke. When the sensor senses smoke, an alarm will be ON at the security chamber near the meeting room. When the alarm rings a security person comes into the meeting room & warns the meeting person not to smoke and manually make the alarm off.
Assignment 6:-
Develop LAD logic for sequential control of two
Motors.
Two motors (M1, M2) are to be separately stated and stop from individual start-stop push button stations. Motor M2 can only be started when Motor M1 starts. Once motor M2 starts it can be separately stopped but if the stop push button for motor M1 is pressed then both motor M1& M2 gets OFF. While running Motor M1 & M2 if a common stop switch is pressed it makes both the motor OFF.
Assignment 7:-
Four pushbutton station controls a fan each station has a start and stops push buttons. Two-door interlock must be closed before the fan runs. When the start Push Button is pressed from any push button station the fan runs and the fan can be stopped from any push button station by pressing the stop push button.
Assignment 8:-
In an automated bus, there are 8 seats for 8 people and each seat has a Pushbutton when any of the Pushbutton is pressed by the passenger an alarm will run so that the driver will know he has to stop the bus. The driver will off the alarm and stop the bus. When the bus is stopped driver will press a pushbutton to open an exit door and another push button to close the door.
Assignment 9:-
The motor starts in the forward direction (Contactor K1) when the forward PB1 is pressed and the motor runs in the reverse direction (Contactor K2) when the reverse PB2 is pressed. When stop PB3 is pressed motor stops. The motor must be stopped before changing direction.
Assignment 10:-
Design a plc program and prepare a typical I/O connection diagram and ladder logic program that will correctly execute the hardwired control circuit in:-
Where CR is Control Relay.
PL is Pilot Light.
PS is Pressure Switch.
SS is Selector Switch.
Assignment 11:-
In a bus, the driver has a pushbutton (PB1). If it is pressed, the back door is open then the front door gets closed which was previously opened. If the pushbutton (PB2) is pressed then the front door gets open & the back door gets closed which was previously open which the driver can control as suitable to him.
Assignment 12:-
In an automated Scotty, its engine will not start if any of the brakes are not applied and the ignition key is not made on. At the running condition of the engine if the brakes are applied there is no effect on the engine. The engine can be stopped by making the ignition key off. In an emergency, an engine stop switch is used to stop the engine.
Assignment 13:-
In a factory control room, there are two sensors entry sensor and an exit sensor at the door.
When the entry sensor senses a man at the door it will send a signal to the indicator panel at the top of the door to glow a RED lamp and make a GREEN lamp OFF which was previously ON. When the indicator becomes RED it will run the motor in forward to open the door. When the door gets fully opened and touches a limit switch the motor gets OFF. When the exit sensor senses the man at the door it will send a signal to the indicator panel to make the GREEN ON which was previously OFF and also it makes the RED lamp OFF. When the indicator panel becomes GREEN it will run the motor in reverse to fully close the door and when it touches another limit switch by closing then the motor gets OFF.
Assignment 14:-
Design a plc program and prepare a typical I/O connection diagram and ladder logic program that will correctly execute the hardwired control circuit in the FOLLOWING FIGURE FOR ELECTRICAL HARDWARE CONTROL WHILE DOING LADDER AVOID OL (OVERLOAD RELAY)
Assignment 15:-
In a workshop six bulbs, one exhaust fans, and three fans are available. The workshop has one control panel board having five push buttons PB1, PB2, PB3, PB4, and PB5.
When the pushbutton (PB1) is pressed six bulbs should glow. When the pushbutton (PB2) is pressed, the exhaust fan should run and it stops the three fans if run previously.
When PB3 is pressed 3 fans get ON and it stops the exhaust fan if runs previously.
But the control panel has two stop pushbuttons one is the emergency pushbutton (PB4) & another is the stop pushbutton (PB5)
In case, if pushbutton (PB5) is pressed 6 bulbs get off.
By pressing the emergency stop, everything will stop.
Assignment 16:-
In a motorcycle, when the key is inserted into the key holder and switched on then the engine gets started by applying a kick or ignition switch. If in between someone makes the key off, then the engine of the motorcycle doesn’t get off. It can only be made off by the engine off switch present at the right-hand side of the handle.
Assignment 17:-
In a tank control system, when a low level of the overhead tank is sensed the motor gets on.The low-level sensor remains in glowing condition till it senses a level high with a green indication lamp to glow. When it senses high motor gets off. The green lamp should glow till the low level is not sensed again. In an emergency, an emergency stop PB is used.
Assignment 18:-
Draw a lad when a bottle is emptied a red indication lamp glows and the red lamp glows till the bottle is filled completely with water. In between the process if someone switches off the input indication then the process does not get hampered. The process stops after the bottle is filled with a green indication lamp to glow. In case of emergency an emergency stop PB is used.
Assignment 19:-
In a factory, there is a conveyer & it operates through a control panel board. When we pressed the PB1, the conveyer is running its full speed & a green bulb will glow on the panel board. When we pressed the PB2, the conveyer ran its medium speed & red bulb will glow on the panel board. When we pressed the PB3, the conveyer ran its a slow speed & a yellow bulb will glow on the panel board.
When we pressed PB4, then all the process is stop.
Assignment 20:-
Draw a lad such that in the city bus service when any passenger presses the stop button from any of the seats a buzzer should sound and if the sound continues, the driver stops the buzzer and also stop the bus. When the bus engine completely stops the hydraulic exit gate is opened by the driver till the passenger gets down and an indication lamp present near the driver glows when the gate opens. When the exit gate is closed by the driver manually indication lamp goes off.
Assignment 21:-
In the food processing industry, the raw materials are loaded into a container having a weight sensor. When the set weight is obtained then an indicator will glow & the output valve of the container will be opened. Then the output of the first container goes to another container for stirring purposes which has a temperature sensor. When the 2nd container is heated & set temperature range is achieved then another output will glow & the output valve of the 2nd container opens & the final output then passes through a filtering process & then give the desired output.
Assignment 22:-
One main conveyor feeds three sub-conveyors. The sub-conveyors are cyclically selected when 100 kg of material is dumped in a particular sub-conveyor. Weight-sensing information comes to the PLC from the load cell as a digital input (toggling type). At any point in time, at least one sub-conveyor will be aligned with the main conveyor to avoid spillover or wastage of material during start-up.
Assignment 23:-
In a long one-way corridor, there are three bulbs (B1, B2, B3) and two doors (D1, D2). One door (D1) is for entry and one door (D2) is for the exit. There are two sensors (S1, and S2). At the entry gate, there is a limit switch (LS IN) and at exit gate, there is another limit switch (LS OUT). There are three rooms (R1, R2, and R3) in the corridor. Each door is supplied with one push button (PB1 for R1, PB2 for R2, and PB3 for R3) and one limit switch (LS1 for R1, LS2 for R2, LS3 for R3).
Logic:
a) When a person comes inside the corridor by opening the entry door LS IN makes the bulb B1 ON when he goes forward by sensing sensor S1 bulb B1 gets OFF and B2 gets ON when he goes forward further, by sensor S2 bulb B2 gets OFF and B3 gets ON when he further go forward to exit gate LS OUT makes the bulb B3 OFF.
b) When the person comes inside the corridor by opening the door LS IN makes the bulb B1 ON but not going forward if he enters the R1 by LS1 bulb B1 gets off if he again comes out of the room R1, to glow B1 he has to press the push button PB1 near to door D1.
c) If he further moves towards the exit or to any other room then the above process has to be repeated.
But finally, the corridor should be always dark when there is no man in the corridor.
All the above logic should be satisfied simultaneously.
Assignment 24:-
The elevator shown in Fig. 2 uses a platform to move objects up and down. The global objective is that when the UP button is pushed, the platform carries something to the UP position, and when the DOWN button is pushed, the platform carries something to the DOWN position.
The following narrative description indicates the required sequence of events for the system:
1. When the START button is pushed, the platform is driven to the down position (initialized)
2. When the STOP button is pushed, the platform is halted at whatever position it occupies at that time
3. When the UP button is pushed, the platform, if it is not in a downward motion, is driven to the up
position.
4. When the DOWN button is pushed, the platform, if it is not in an upward motion, is driven to the down
position.
Inputs:
START: – I 0.0
STOP: – I 0.1
UP: – I 0.2
DOWN: – I 0.3
LS1:– I 0.4
LS2:– I 0.5
Outputs:
M1 (up motor):- Q 0.0
M2 (down motor):- Q 0.1
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