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Let us summarize.
Slide 1: Welcome to the Spoken Tutorial on Overview of OpenPLC with LDmicro.
Slide 2: Learning Objectives In this tutorial, we will learn about
  • PLC
  • OpenPLC and LDmicro
  • Features of OpenPLC
  • What you can expect in this series
  • The content available in various tutorials in this series
  • How to use the Code files given in each tutorial
Slide 3: System Requirements To record this tutorial I’m using
  • Ubuntu Linux 18.04 operating system
Slide 4: Pre-requisites To follow this tutorial you should have the basic knowledge of
  • Electronics and
  • PLC
First let us understand PLC.
Slide 5(a):

Introduction to PLC:

  • PLC stands for Programmable Logic Controller.
  • PLC is an industrial digital computer.
  • It is used for the automation of various electro-mechanical processes.
Slide 5(b):

Introduction to PLC:

  • A PLC program is usually written on a computer and then it is downloaded to the controller .
  • PLC is programmed using special programming languages like ladder logic, function blocks etc.
Slide 6:

Embedded devices vs PLC

  • Now you may ask, “Why not use embedded devices for these processes?”
  • PLCs are designed to be shock-resistant, suitable for harsh environments.
Now we will learn about OpenPLC.
Slide 7:

About OpenPLC

  • OpenPLC is an affordable open source hardware developed at IIT Bombay by the FOSSEE team.
  • It is designed to get hands-on PLC programming experience at an affordable cost.
  • OpenPLC can be programmed using ladder logic.
Now we will learn about LDmicro
Slide 8:

About LDmicro

  • LDmicro is an open source software.
  • It is used to draw ladder diagrams and generate .hex files for OpenPLC.
  • LDmicro was available only for Windows initially.
  • The FOSSEE team from IIT Bombay ported it and made it available for Linux OS also.
Open web browser >> type Let us go to the OpenPLC website developed by the FOSSEE team.

Please go through the website for detailed information on OpenPLC.

Homepage In the Home page we can read more information about PLC and the motive behind OpenPLC.
Resources page The Resources page has git repository links for hardware designs and LDmicro source code.
Downloads page The Downloads page has links to download LDmicro, AVRDUDE and USBasp drivers.
Slide 9:

Features of OpenPLC

Features of OpenPLC
  • OpenPLC has all the capabilities of an industrial PLC and is simpler to work with.
  • It is a modular hardware.
  • It uses ladder logic programming, which is one of the easiest and efficient.
  • For example, it can be interfaced with electronic modules like relay modules etc.
  • These are readily available in the market.
Slide 10:

What can you expect in this series?

What can you expect in this series?
  • Each tutorial is demonstrated with simple experiments using instructions of LDmicro.
  • LDmicro has a simulation feature.
  • It allows us to check the code before uploading it on to the OpenPLC Mainboard.
  • This is helpful to avoid any hardware damage.
  • Once we are sure that the logic is working, we can compile the logic.
  • That is to generate the .hex file for the same in LDmicro to upload it to OpenPLC Mainboard.
  • In this series, we have used some custom modules such as
    • Traffic Light module
    • Switchboard module
    • Heater module
  • Using these modules we will check the working of the ladder logic that we have created on hardware.
Slide 11:

Who can use OpenPLC?

OpenPLC can be used by anyone who is interested in PLC programming.

For example:

  • Polytechnic, Engineering and other technical students
  • Any hardware professional
  • Individuals who are interested in hands-on experimentation.
Now, we will briefly go through the individual tutorials in this series.
Show Installation tutorials of windows and Linux The first two tutorials in this series explains-
  • How to install LDmicro on Ubuntu Linux OS and Windows OS.
  • How to install AVRDUDE and USBasp drivers.
Introduction to LDmicro

Simulation and Compilation

OpenPLC Mainboard

Programming OpenPLC

Next four tutorials are about
  • How to navigate and create a ladder diagram in LDmicro.
  • How to simulate and compile that ladder diagram in LDmicro.
  • About OpenPLC Mainboard and
  • How to program it with the ladder diagram created.
OpenPLC Traffic Light and Switchboard Modules Then we will learn about
  • OpenPLC Traffic Light module and OpenPLC Switchboard module and
  • How these modules can be interfaced with OpenPLC Mainboard.
Normal Coil

Normal Contact

Negated Coil & Negated Contact

In the next four tutorials,
  • We will learn about the most basic instructions of ladder logic, Contacts and Coils.
  • We will learn about the working of Normal Coil, Normal Contact, Negated Coil and Negated Contact
  • These are explained with simple examples using switch and LED.
Implementing NOT & AND logic gates

Implementing OR & XOR logic gates

Internal Relay & Output pin


After this, we will learn
  • How to implement basic logic gates like NOT, AND, OR and XOR using Contacts and Coils.
  • Also about Internal relay and Output pin
  • Working of the SET and RESET Coils.
All the above topics are covered under the Basic level.

Next comes the Intermediate level tutorials.

One shot instructions

Arithmetic instructions

Move instructions

Compare instructions

Here we will learn about
  1. One shot instructions
  2. Arithmetic instructions
  3. Move instruction and
  4. Compare instructions

We will learn about the importance of cycle time and how to create a virtual counter.

TON & TOFF Instructions

RTO Timer Instruction

  • Next we will learn about the different types of timers available in LDmicro.
  • The difference between each timer, particularly between TON and RTO.
  • Also we will learn when to use RESET instruction.
CTU Counter

CTD Counter

CTC Counter

  • After that we will learn about the different types of counters available in LDmicro.
  • We will learn how to create up-down counter using CTU and CTD counters.
OpenPLC Heater module

AD Converter Read Instruction

PWM Instruction

  • Next we will learn about the working of OpenPLC Heater module.
  • How it can be used to learn some analog instructions available in LDmicro.
  • One of the instructions is A to D converter read.
  • As an example we will try to regulate the temperature of the resistor on the Heater module.
  • Then we will learn about PWM instruction by controlling the speed of the fan on the Heater module.
Slide 12: How to use the Code Files? How to use the Code files?
  • Code files are available in the Code files link of that particular tutorial.
  • The .ld file can be accessed by opening them in LDmicro using ‘Open’ option under ‘File’ menu.
  • The ladder diagram can then be compiled to generate a .hex file.
  • Or you can download the .hex file from Code files which can be uploaded to the Mainboard directly.
  • It is not recommended to download the Code files without understanding the working.
  • Follow all the steps as shown in each tutorial and understand the working of each instruction.
  • It is the better way of learning.
This brings us to the end of this tutorial.
Slide 13: Summary In this tutorial, we have learnt about
  • PLC
  • OpenPLC and LDmicro
  • Features of OpenPLC
  • What you can expect in this series
  • The content available in various tutorials in this series
  • How to use the Code files given in each tutorial
Slide 14:

About Spoken Tutorial project

The video at the following link summarizes the Spoken Tutorial project.

Please download and watch it

Slide 15:

Spoken Tutorial workshops

The Spoken Tutorial Project team conducts workshops using spoken tutorials and
  • gives certificates on passing online tests.

For more details, please write to us.

Slide 16:

Answers for THIS Spoken Tutorial

  • Do you have questions in THIS Spoken Tutorial?
  • Please visit this site.
  • Choose the minute and second where you have the question.
  • Explain your question briefly.
  • The Spoken Tutorial project will ensure an answer.
  • You will have to register to ask questions.
Slide 17:

Forum for specific questions:

  • The Spoken Tutorial forum is for specific questions on this tutorial.
  • Please do not post unrelated and general questions on them.
  • This will help reduce the clutter.
  • With less clutter, we can use these discussions as instructional material.
Slide 18:

Forum for specific questions:

  • Do you have any general / technical questions on OpenPLC?
  • Please visit the FOSSEE forum and post your question.
Slide 19:


Spoken Tutorial Project is funded by MHRD, Government of India.
Slide 20:

Thank you slide

This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.

And this is Harsha Priyanka from FOSSEE team, signing off. Thanks for watching.

Contributors and Content Editors

Nancyvarkey, Nirmala Venkat