PLC Programs

1. Aim:- To develop ladder diagram for ON/OFF temperature controller for the continuous process of heating of mixture.

Sequence:

1.      On button to start process when motor start and V1 is open.

2.      Then  check the level, is it high level is reached or not.

3.      If high level is reached turn ON the stirrer & heater at a time.

4.      After mixing & heating turn OFF the stirrer & heater.

5.      Finally release this mixture through valve V2.

2. Aim: - Develop a ladder program for wood saw cutter.

Process: - A wood saw cutter (W), a fan (F) and a lubrication pump (P) turns on when a START push button is pushed. Following is the stopping sequence:

STOP push button stops the saw only, before fan stops it should run for an additional 5 sec to blow the chips away and also the tube pump is to run for 8 sec. additionally before it stops. if the saw has run more than 1 min, the fan should stay ON indefinitely. The fan may be turned OFF by pushing a separate fan reset switch.

3. Aim: - Develop ladder logic to fill the tank.

Process: -  Fill the tank up to 80%. When tank is filled, turn ON the heater to rise the temperature up to 70 ⁰ c. when this temperature is reached, turn OFF the heater & open the outlet valve. When level in tank falls below 10%, close the output valve.

4. Aim: - Develop ladder logic for traffic control.

Process: - we have to control traffic of 4 roads. The green light of each side is ON for 10 sec only one side at a time and the same time, the respected red light is ON for 30sec. the same sequence is followed by each side.

5. Aim: - Develop ladder logic for an automatic paint process.

Process: - When ON button is pushed, a stacker starts stacking plywood sheet at position A. stack height is controlled by PLC counter function. When 12 parts (stack) are placed on the conveyor, it turns ON and moves the stack at the position B. a sensor is used to stop the conveyor at B. At point B, paint is applied for 12 sec after painting is completed, the conveyor restart s manually and moves to position C and stops automatically and stack is removed.

Sequence: -

1. ON button is used to start the process and stacker starts stacking.

2. Sensor is used to count the no. of sheets.

3. After 12 part stacking, conveyor start and moves stack to position B. when it reaches to position B, sensor stops the conveyor by sensing the position.

4. Paint is applied to 12.5 seconds duration.

5. After painting, conveyor starts manually and moves stack to position C and stops automatically.

6. Aim: - Develop ladder logic for Heat/Quench station.

Process: -

1.      Master PB is used to turn ON the process.

2.      Object is placed on the mandrel

3.      Both left & right start up buttons is pressed.

4.      Push  stop PB to stop process.

5.      The object is raised from down to top by air pressure. A solenoid valve supplies this air to pneumatic elevating cylinder. The lower limit switch is getting actuated before object will rise. Lower limit switch actuation indicates that there is an object on mandrel and that mandrel is down.

6.      The mandrel makes contact with a limit switch at the top of travel.

7.      Heat comes ON for 10 sec and goes OFF.

8.      Quench comes ON for 8 sec.

9.      The object returns down and upper limit switch become indicated.

10. As it gets down, down limit switch get actuated.

11. The object is then removed.

7. Aim: - To develop the ladder diagram using analog input for multi-input tank level controller.

Process sequence: -

1.      Add component (A) to tank up to level A. then add component (B) to tank up to level B.

2.      Stop feeding tank. Turn ON stirrer for 10 sec.

3.      Open discharge valve, when level again goes to A.

4    4. Stop the process

8. Aim: Develop ladder logic for the coal handling process.

Process: Coal plant consist of following main equipment

1. Storage tank: It stores coal in huge amount & supplies it to primary crusher as per requirement.

2. Primary crusher: It crushes the coal from bigger size to smaller size & supplies it to secondary crusher.

3. Secondary crusher: Two crushers are used to decrease the load of crushing .secondary crusher crushes the small sized crushed coal coming from the primary crusher to powdered form.

4. Coal mill: This is mixture which mix coal powder coming from secondary with hot air coming from air pre-heater & forced it into furnace.

Sequence event:

When we press START, it starts motor M1 & opens the C1 which pass coal from storage tank to primary crusher.

1) When level ML1, reaches O: 0/1 wills ON, it starts motor M2 & M3, which crushes coal in small part & pass to secondary crusher.

2) When level ML2 reaches O: 0/2 wills ON, it starts coal mill, starting motors M4, M5, M6 & M7.

9. Aim: Develop ladder logic for automatic door opening of the room.

Process: The process includes following sequence of events.

1.    When the start PB is pressed, the RTD will sense the temperature of the room. This will be considered as I/P to the analog input of PLC.

2.    When the temperature of the room is greater than 25⁰ c, then AC-I will be latched. When temperature of room is greater than 35⁰ c, then AC-II will be latched.
3.    When the temperature of the room is below 20⁰ c, then Ac-I will be unlatched. If the temperature of the room is less tan 30⁰ c, AC-II will be unlatched.
4.    When a person enters or leave the room, then laser beam contact will be break & this gives the change in the LDR, the door will open for 5 sec.

10. Aim: - Develop the ladder program for the process of alternate rotation of the motor.

Process: - Here, motor with two switches is used as shown. When the start button is pushed, the motor starts rotating towards the RLS and LLS.

Sequence: -

1.      When ON button is pushed, the motor move the arm to the right limit switch position and waits for 30 sec.

2.      The motor then cycles 75 times between the right to left switches and then stops.

3.      The OFF button stops the motor at any time or after 75 cycles have been made.

11  Aim: - To develop the ladder program for an oven using the process bits.

Process: - Process sequence is as follows-

1.    When START button is pressed, the valve V1 is turned ON till HL (high level) is reached.

2.    After HL is reached, V1 will close and heater and indicators are turned ON for 30 sec.

3.    After 30 sec, valve V2 will turn ON for 20 sec to draw the hot water from the tank

If STOP button is pressed during any time of the process, heater will be turned OFF but V2 output will be kept ON for 20 sec. After this, the process will stop.

12. Aim: Develop ladder logic for an automated hydrophobic system. PLC will be used to provide the following sequence of light and nutrients.

Process:

1.    The growing plant (Vat) must have light. A photo switch which closes on rising light level , monitors  natural light during this period. If the light intensity falls below the switch level for more than 10 sec an artificial light is turned on until natural light brightness again.

2.    During this period, nutrient must be cycled into the plant. Valve V1 will turn ON till level L1 is reached. After that, valve V1 will close and nutrients must stay there for 20 sec.After that pump will start to drain the nutrients again to the tank, till level L2, pump will stop and again V1 will start.

13. Aim: - To develop ladder logic or the heating process.

Sequence: -

1.      When START button is pressed, the valve V1 is turned ON till the high level (HL) is reached.

2.      After HL is reached, valve V1 will close and heater and indicator turn ON for 30 sec.

3.      After 30 sec, valve V2 will turn ON for 20 sec to draw the hot water from the tank.

4.      If STOP input is activated during any time, the heater will turn OFF but the valve V2 will be kept ON for 20 sec and after this, process will stop.

14. Aim: - To develop the ladder program for the process of wrapping the chocolate boxes.

Process: - A machine is designed to wrap the chocolate boxes. The boxes are arriving on the conveyor belt.

Sequence: -

1.      The presence of box is determined by the optical sensor (P). After this, the conveyor is stopped (C) and the box is clamped in place (H).

2.      A wrapping machine (W) is turned ON for 10 sec.

3.      A sticker cylinder (S) is turned ON or 5 sec to put the sticker on the box.

4.      The clamp (H) is turned OFF and the conveyor C is turned ON.

After the box leaves, the system returns to an ideal state

15. Aim: - To develop the ladder program for the process in which the tank is filled 80% by analog input. The heater start for particular time and the output valve open when 10% water level remains. Then again feed the water in the tank.

Process: -

1.      In this process, when start button is pushed, the tank is starting to fill by inlet valve V1.

2.      When level in the tank reaches at 40% by analog input, valve V1 closes, valve V2 opens and fills the tank till level reaches 80% then heater starts for pre-determined time.

3.      When temperature reaches to 60⁰c, then heater stops and outlet valve open.

4.      When level in the tank reaches to 10%, then the inlet valve V1opens and outlet valve is closed.

16. Aim: - To develop the ladder diagram and mimic diagram for the bottle filling process.

Process: - In this process, the conveyor belt moves the bottles on it. When the bottle is sensed by the bottle present sensor, the conveyor motor stop and the valve is opened for filling the bottle. When bottle full indicator is ON, valve gets closed and conveyor motor start. Again next bottle is sensed by the sensor and whole process goes on.

17. Aim: - To draw the ladder diagram and mimic diagram for the automatic metal cutting process.

Process: - In this process, a metal sheet is allowed to move on the conveyor belt. When the metal sheet is sensed by the sensor, a holder holds the sheet at that instant and at the same time cutter cuts the sheet at the desired place. When cutter cuts the sheet, then sheet roll is released and cut sheet is passed towards the tray which carries that sheet. The whole process repeats until STOP button is pressed.