PLC programming (Ladder) examples

PLC practice problems

1.1. When someone enters the infrared sensing field, opening motor starts working to open the door automatically till the door touches the opening limit switch

If the door touches the opening limit switch for 7 sec and nobody enters the sensing field, the closing motor starts working to close the door automatically till the closing limit switch touched together.

Stop the closing action immediately if someone enters the sensing field during the door closing process.

1.2. Detecting the standing bottles on the conveyor and pushing falling bottles in tray.

1.3. Write PLC ladder logic to detect burglar and activate the alarm if windows or proximity sensor detects any movement

1.4. Write a PLC ladder logic to show the total no of cars in car parking

1.5. Write a PLC ladder logic to automate car washing process in which when a car comes in soap gets sprinkled for certain time than water and the conveyer moves to the point where the hot air will dry the car and process completes.

1.6. Write a PLC ladder logic to show total no of people in a classroom and control the Entrance and Exit according to no of people in the classroom.

        1.7. There are 3 groups participating in the quiz game: pupils, high school students and professors. If they want to get the chance of answering the question from the host, they must press the answer button on their table first. Other groups’ pressing will be invalid if any group gets the chance successfully
    • There are 2 answer buttons for the pupil group and professor group and 1 answer button for the high school student group. In order to give preferential treatment to the pupil group, Y0 will be ON if any one of X0 or X1 is pressed. However, in order to limit the professor group, Y2 will be ON when X3 and X4 are pressed at the same time. For the high school student group, Y1 will be ON when X2 is pressed.
    • If the host presses X5 (Reset button), Y0, Y1 and Y2 will be OFF.

1.8. Switching on/off the Lamp whether they are at the bottom or the top of the staircase.

1.9. Automatically infusing the container with liquids A and B in order when START is pressed. When it reaches the set level, mix the two liquids evenly then open the valve to let out the mixture.

1.10. Once the photoelectric sensor detects 10 products the robotic arm will begin to pack up. When the action is completed, the robotic arm and the counter will be reset.

1.11. Control Spray-Painting operation in PLC using Ladder diagram programming language.

1.12. Different objects are moving on a conveyor belt. Let’s say, circular balls, square blocks and rectangular blocks. All three types of objects are collected in the same sized box. As these types are different in size and shapes as well, number of objects to be placed are different for each type. Set counter value according to different sized objects’ detection. Implement automation of this in PLC using Ladder Diagram programming language.

1.13. Two tanks have same products filled. Draining from these depends on the requirement from the storage tank. Implement automation of this draining system in PLC using Ladder Diagram programming language

1.14. There are certain objects moving on conveyor belt. Time of an object to reach from one end to another end of the conveyor is to be measured. Implement this in PLC using Ladder Diagram programming language.

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CHANGING THE ARDUINO(ATMEGA328) PWM FREQUENCY

CHANGING ARDUINO PWM FREQUENCY In some projects like boost and buck converters we may need to change the default frequency of Arduino PWM pins according to our need in order to control the charging time of inductor. in Arduino UNO pins D5 and D6 have PWM frequency of 62500 HZ , pins D3, D11, D9 and D10 has the default PWM frequency of 31250 HZ . To change the PWM frequency following code can be written in setup function to set PWM frequency Divide the base frequency of pins by the factor you want to decrease the frequency for each pin some examples are shown below The divisors available on pins 5, 6, 9 and 10 are: 1, 8, 64, 256, and 1024. The divisors available on pins 3 and 11 are: 1, 8, 32, 64, 128, 256, and 1024. for D3 and D11 TCCR2B = TCCR2B & B11111000 | B00000001; // for PWM frequency of 31372.55 Hz TCCR2B = TCCR2B & B11111000 | B00000010; // for PWM frequency of 3921.16 Hz TCCR2B = TCCR2B & B11111000 | B000000...

NRF24 based remote with Arduino Nano

MAKING A DRONE REMOTE to make the drone remote you will need following components:- nrf24 rf module(two) joystick module(two) arduino nano (two) capacitors (one) now connect the components in following way :- connection of nrf24 for both transmitter and receiver are same. there are some additional connections to be made in transmitter to read data from joystick so and connnect the joystick pins in following way Right joystick y axis pin = A0; Right joystick x axis pin = A7; Right joystick switch pin = A6; left joystick y axis pin = A1; left joystick x axis pin = A5; left joystick switch pin = A2; now after connecting the above circuit upload the following codes given for transmitter and receiver and you will get the data as shown below in receiver side. now transmitter code is as follows #include <SPI.h> #include "RF24.h" const int Ry = A0; const int Rx = A...

Closed loop Control of DC to DC boost converter

DC-DC boost converter boosts the DC input voltage to higher DC voltages according to the duty cycle of PWM applied to the mosfet used to charge the inductor.While the mosfet state is on the inductor gets charged, than when the mosfet turns off the voltage stored in inductor and input voltage gets added and appears in the output. But if only these components are used output Voltage will be pulsating and have a frequency similar to that of mosfet switching. So we need to put a capacitor in output in order to oscillating output to smoother output. Still the stored voltage in capacitor will backflow through the mosfet when it is on, So we need to place a diode in between mosfet and capacitor in order to prevent backflow of stored charge in capacitor.After these circuit requirements are completed the boost converter will be boost low voltage DC input to higher DC voltages.The circuit should look like as shown below:- Boost Converter Circuit Output Voltage calcu...

DC-DC buck converter

DC-DC buck converter converts DC voltage from higher voltages to lower voltages according to the duty cycle of PWM applied to the MOSFET gate. When MOSFET is fired the inductor and capacitor gets charged so when MOSFET turns off the inductor and capacitor works as current and voltage source and continue to supply steady voltage and current till the MOSFET is fired again. For the inductor and capacitor to continuously supply the power to load without any ripples the inductance and capacitance of inductor must be high enough so that the change in their voltage and current is not significant. Buck converter circuit output voltage the output voltage of the converter depends on the duty cycle of the PWM applied to the MOSFET gate. output voltage = Duty cycle * Vin Duty cycle = Ton/(Ton+Toff) with the change in load and change in input voltage the output voltage may vary, i...

A4 size CNC pen plotter

Following components were used in this project: Nema 17 stepper motors -2 Threaded rods - 2 Steel rods - 4 linear bearings - 6 Servo Motor -1 Arduino uno - 1 Arduino Stepper motor driver shield Aluminum brackets and plywood Following software was used for this project GRBL Arduino library Universal gcode sender Inkscape for image to gcode conversion Following video and pictures show the working and some outcomes of the project Results:

Using PWM with ESP32 boards

Unlike Arduino boards like UNO, MEGA and many others, ESP32 board does not support analogWrite() command while programming with Arduino IDE. This is because in the Arduino IDE board library for ESP32 does not contain predefined analogWrite( ) function. This is because ESP32 offers many more features with its Digital to Analogue converters, which cannot be fully utilized by analogWrite() function. ESP 32 board can output PWM signals with any frequency the programmer wants upto 40MHZ. but in other arduino boards like arduino uno only selective frequencies are available. ESP 32 also offers DAC resolution upto 16 bits. In this board the relation between ADC resolution and PWM frequency is inverse. The maximum PWM frequency with the currently used ledc duty resolution of 10 bits in PWM module is 78.125 KHz . The duty resolution can be lowered down to 1 bit in which case the maximum frequency is 40 MHz , but only the duty of 50% is available. Available DAC pins in ESP32 can be ...

ESP8266n based home automation project

IOT HOME AUTOMATION USING NODE MCU In this post you will see how to make a system that lets you control your appliances using a node mcu board . Node mcu board is a development board consisting of a esp8266 wifi module along with programming circuits. you will need following parts for this project :- 1.NODE MCU board 2.relay module or some relays and transistors 3.matrix board 4.screw connectors or headers 5.5v power supply 6.USB cable now follow the instructions below 1.connect your node mcu to computer and open arduino IDE 2.Now go to preferances and add this url in arduino board manager url http://arduino.esp8266.com/stable/package_esp8266com_index.json 3.now go to tools/boards...

Demand Side Management in a solar microgrid

SCADA in hybrid energy system management and control for isolated DC micro-grid . Our system addresses the problem of connecting different Energy sourced together effectively, monitoring and controlling of the Hybrid energy system formed by different renewable energy sources. Article in the link can be followed for more information. https://www.sciencedirect.com/science/article/pii/S2352484720314554 For our project we developed a small version of DC micro grid taking power from different power sources (Like solar and wind) and combining these sources together with the help of voltage stabilizing buck-boost converters. After we boot the voltages from different sources to our distribution voltage. We distribute the power for different loads like Households, Hospitals, Schools through dedicated feeders. Now with the help of SCADA and Sensors we can monitor various system parameters like Generation voltage of different sources, Bus voltage, powe...

Parallel operation of boost converters in priority-based power sharing mode

Priority based power sharing in parallel connected boost converters is one of the simplest power sharing scheme to run the boost converters in parallel operation. in this simulation it is considered that the boost converters are physically not far from each other, and the controllers of the converters can communicate with other. One of the converters will run on higher priority which means that that converter will supply as much power as it can to the bus, and another will only supply additional power required to maintain bus stability i.e: maintain the bus voltage. Following figure shows the hardware setup of the experiment. Figure: Boost converter parallel operation experimental setup this configuration of the converter is applicable in the conditions where we need to draw as much power from a source as possible and draw only additional power required to maintain bus voltage from the secondary source. An example application case would be when there is a solar and battery-based hom...

Project gallery

Some of the photos of my projects that managed to survive long enough on my gallery. fig : RLDA data acquisition project (2023 February) fig : DAQ preparation for RLDA (2023 February) fig : DAQ controller board (2023 February) fig : DAQ system testing on bump rig (2022 November) fig: 8 channel strain gauge DAQ system with 10 uV precision and 1000 HZ sampling frequency (2022 November) fig : 8 channel strain gauge DAQ board Ki-CAD PCB (2022 October) fig: PCB wire tresses (2022 October) fig : Four channel 24 bit ADC board interfaced with teensy4.1 for high speed data acquisition fig : four channel instrumentational amplifier (2023 January) fig : Ki-CAD PCB design four channel instrumentation amplifier (2023 October) fig : Instrumented bike chassis (2022 October) fig : Half bridge strain gauge application on steel rod (2022 October) fig : STM 32 pneumatic rig control board (2022 September) fig : Strain gauge data verification setup (2022 September) fig : Instrumentation amplifie...

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