learning

Dear existing & future PLC software developers, I have published part 13 of my free PLC programming using TwinCAT 3 tutorial.

Proper version control is traditionally not done in the world of automation, which is a big shame. The question should not be whether version control should be used or not. The question should instead be what version control system should be used. In this part we will get an introduction to version control in general, and Git in particular. We will start with an introduction to some basic concepts of version control and then show you how you can put your automation projects under version control using Git, using free and open-source tools that are traditionally used in the software industry. You’ll learn how to do proper 100% free and Git-based version control using TwinCAT 3! Let’s start demanding more from our automation vendors and demand that the tooling for version control should be included by default, and get out of the dark ages!

Read more

Dear existing & future PLC software developers, I have published part 12 of my free PLC programming using TwinCAT 3 tutorial.

When installing the TwinCAT development environment and runtime you get access the core functionality, but sometimes you might want to extend this with additional functionality as for example adding an SQL database connection. In this chapter we will investigate some TwinCAT functions that can be added.

Read more

Dear existing & future PLC software developers, I have published part 11 of my free PLC programming using TwinCAT 3 tutorial.

When you start to develop PLC software and you’ve worked for a few projects, you will come to a point where you will notice that certain parts of the software, like function blocks, will be copied between the projects. You’ll either do it by simple rewriting the same functions or function blocks again, or you will simply copy and paste it from one project to another. Also, once a project gets big enough, you will want to utilize something called libraries. With this we can achieve code re-use.

Read more

Dear existing & future PLC software developers, I have published part 10 of my free PLC programming using TwinCAT 3 tutorial.

When designing and building a control system you will eventually want the control system to actuate something, be it a relay, a motor, a pneumatic system or maybe a complete 6-axis robot. To get feedback of the actuation, sensors are needed. In this part we will cover how we communicate with the environment using inputs and outputs.

Read more

Dear existing & future PLC software developers, I have published part 9 of my free PLC programming using TwinCAT 3 tutorial.
In this part we’ll learn how to use one of the most used Beckhoff libraries for various purposes. We’ll learn how to measure execution time of PLC code, how to use a FIFO buffer and how to combine the power of using a TwinCAT real-time program with an application running in user-space (Windows).

Read more

Dear existing & future PLC software developers, I have published part 8 of my free PLC programming using TwinCAT 3 tutorial.

As TwinCAT 3 conforms to the IEC61131-3 standard, there are certain things it has to be able to do. The Tc2_Standard library has many of the standard IEC functions such as timers and triggers, which we will look into in this part of the tutorial.

Read more

Dear existing & future PLC software developers, I have published part 7 of my free PLC programming using TwinCAT 3 tutorial.

In this part we will go back to basics of IEC 61131-3 and structured text and look into instructions. This will cover IF/ELSE, CASE-switches and FOR/WHILE-loops. We will utilize our knowledge to write a CSV (comma separate value) event logger by using a state machine.

Read more

Dear existing & future PLC software developers, I have published part 6b of my free PLC programming using TwinCAT 3 tutorial.

In this part we will continue our journey of the object oriented features of IEC 61131-3 and look into something called interfaces. Interfaces provide a layer of abstraction so that you can write code that is ignorant of unnecessary details. Interfaces aid you in designing more modular and robust software. With interfaces it’s possible to decouple direct dependencies between objects in your software.

Read more

Dear existing & future PLC software developers, I have published part 6a of my free PLC programming using TwinCAT 3 tutorial.

In this part we will start to look into the object oriented programming parts of structured text and IEC 61131-3 called function blocks, and I think it’s here things are really starting to get fun! For those that are Java, C, C++ or just “traditional” programmers, going into the realm of function blocks is like going from C-style structures and functions, and into classes in C++. With function blocks we can go from working in a procedural style programming into objected oriented style programming.

Read more

Dear existing & future PLC software developers, I have published the 5th part of my free PLC programming using TwinCAT 3 tutorial.

Arrays allow us to define types of variables that can hold several data items of the same kind. In this part of the tutorial we will look at a data unit type that allows us to hold several data items of different kind. We will also look at one of the basis of modularization and re-use in software development called functions. We will look at how we can get data in and out of functions, and we will also look at the difference between passing parameters by value and by reference. We will finish this part by writing our very first function!

Read more