In this tips and tricks post I will demonstrate the usage of the attribute: ‘instance-path’. The instance path attribute allows you to get the instance path of the containing POU in a string variable. Something I find particularly useful for error-logs and debug messages. How to use it 1. We need a string variable which […]
Tag: IEC 61131-3
TwinCAT meets Project Euler
During the latest COVID lock down, scrolling randomly through the internet, I stumbled on Project Euler, a series of mathematical/computer programming problems. So I thought it would be fun to try a few challenges with Structured Text. After completing the first 2 challenges it occurred to me that it might be fun to publish a repo on Github with this project, to see if I can get more people to solve challenges and on the fly creating a lot of mathematical Structured Text example code.
You should use AND_THEN. OR_ELSE?
In this post I’ll discuss the operators ‘AND_THEN’ and ‘OR_ELSE’. Operators which I find really useful from time to time.
Instance variables with VAR_INST
Instance variables are available for funtion block methods. Unlike ‘normal’ variable their values are preserved between method calls.
STweep – The formatter for Structured Text
STweep is a formatter for Structured Text integrated in Codesys and TwinCAT. STweep assists in enforcing a consisting code style!
Communicating between Beckhoff controllers part 2: ADS
In part 2 of the series: “Communication between Beckhoff controllers” we discuss the protocol Automation Device Specification or ADS.
Tips and Tricks: Arrays are value types!
In TwinCAT arrays are treated as value types. In this post I show an example of this behavior as well as some alternatives.
Fluent interface in Structured Text
A popular programming design in high level languages as C# is the so-called ‘fluent code’ or ‘fluent interface’. But what is a fluent interface and how can we implement this in Structured Text? In this post I briefly explain what a fluent interface is and give an example of a fluent interface in Structured Text.
The ABSTRACT keyword
It was already available in CODESYS, but with the release of TwinCAT 4024 it’s now available in TwinCAT as well: the ABSTRACT keyword. Abstraction and the use of the abstract keyword is common practice in OOP and many higher level languages as C# support this. It’s often considered as the fourth pillar of OOP. In this post i’ll explain how to use the ABSTRACT keyword in TwinCAT with some practical examples.
Keep your online view clean: The hiding attributes
In the post ‘How to use monitoring attributes’ I showed how to use the monitoring attributes: attribute ‘monitoring’ := ‘variable’ and attribute ‘monitoring’ := ‘call’. With these pragma attributes we can monitor and modify our function blocks properties. This comes however with a small drawback. As the online view now shows your properties and their backing fields your online view gets less clear. In this post I will show how to solve this with the hiding attributes.
The three pillars of OOP – Inheritance
With the object orientated options we’ve got available with IEC 61131-3 last years the time has come to talk about design patterns and best practices in the world of PLC programming. In this series of three posts ‘The three pillars of OOP’ I will explain the concepts of: Encapsulation, Inheritance and Polymorphism with some examples in TwinCAT. This post is about the second pillar ‘Inheritance’.
The three pillars of OOP – Encapsulation
With the object orientated options we’ve got available with IEC 61131-3 last years the time has come to talk about design patterns and best practices in the world of PLC programming. In this series of three posts ‘The three pillars of OOP’ I will explain the concepts of: Encapsulation, Inheritance and Polymorphism with some examples in TwinCAT. This post is about the first pillar ‘Encapsulation’.
How to use monitoring attributes
Every programmer spends a considerable amount of time debugging their software. In the world of PLC programming it’s common to login to the PLC and monitor and write your variables. However, with the introduction of properties for your function blocks monitoring is not as plain as it used to be. In this post I’ll explain how to use monitoring attributes for your properties in TwinCAT.
A Code Jam challenge with Structured Text
Every year I participate in a number of online code challenges like Facebook Hacker Cup, Google Code Jam and Advent of Code. Although I never make it really far I quite enjoy the puzzles which I usually make in C#. Definitely not the fastest language out there, but LINQ makes life easy 🙂 . Since I spent every week a considerable amount of time PLC programming, I found myself wondering if I could solve A Code Jam challenge with Structured Text. Spoiler alert, yes you can, but it doesn’t come very easy.. So I decided to write a small post about it, pointing out the challenges I faced.