What is Structured Text

Structured text, abbreviated as ST or STX, is one of the five languages supported by the IEC 61131-3 standard, designed for programmable logic controllers (PLCs). It is a high-level language that is block-structured and syntactically resembles Pascal, on which it is based. All of the languages share IEC61131 Common Elements. The variables and function calls are defined by the common elements so different languages within the IEC 61131-3 standard can be used in the same program. Complex statements and nested instructions are supported.

At first, it may seem better to use a graphical programming language for PLC programming but there are pros and cons in each case. Like me, I have come to PLC from higher-level programming languages such as C/C++, so this fits better to me. The same general compilation process is used here. 

We shall use Visual Studio for program development and download to PLC or simulator.

Download all the necessary tools to start with Structured Text

Start downloading the necessary tools and run the first program.

This page will guide you about the tools and show how to produce the first program for Beckhoff PLC in a simulator. Please follow the page.

Learn what is timer and how it works in Structured Text with example

Timers play a vital role in automation systems. A timer is a control device that outputs a signal at a preset time. Based on the signal, the automation system can do useful work. For example, we can check every 200 MS interval if the water tank has been full or not. If the tank has been full we can stop the motor, for example, know the basics of the timer from these examples.

Learn about state machine in Structured Text

What is a state machine and how do we design in PLC. This article will describe step by step guide on how to design a state machine in a structured text programming language. We shall show how to design our main gate opening and closing as a state machine. Continue reading the article and how to develop PLC software 

This section describes about array and enumeration in Structured Text

Array Struct and enum. This section will focus on how to use an array in structured text with examples. Continue reading the tutorial. Continue for the hands-on examples.

Different data type used in Structured Text is explained here with sample

PLC data type in structured text:

Memory is a limited resource in any hardware device. This page will explain how memory works in Beckhoff PLC and how to use it in PLC software. Please follow this link for more.

Pointer, memory, addresses are explained here with sample.

Pointer and Memory in structured text:

Memory is a limited resource in any hardware device. This page will explain how memory works in Beckhoff PLC and how to use it in PLC software. Please follow this link for more.

Anatomy of persistent data in TwinCAT system

Persistent data are very important in any system, if the data is lost somehow the system may not work at all or the performance will be very poor. It is good to do a backup of the system and if malfunctions happen then we can restore it quickly. This section will describe how we can do back or what that back means. Continue reading the article.

Task, scan time, etc are explained here

PLC Task and Scan time in structured text:

Memory is a limited resource in any hardware device. This page will explain how memory works in Beckhoff PLC and how to use it in PLC software. Please follow this link for more.


What is MQTT, Start from here

Convert your PLC application to an OPC UA compatible

What is OPC UA and how a ST program can be converted to an OPC UA  Server. Our PLC can be used as a OPC UA Server if we just install the OPC UA module from Beckhoff. Continue reading the article.

What is function block? The answer is here

Function and Function block in structured text:

Function block in structured text is a independent code unit that can be used to model a device. It is one of the POU. Please follow this link for more.

How to find a PLC that is  connected in the internet?

This tutorial will show how to add route to PLC program so that the PLC program can find the PLC in question. The PLC can be located on theinternet in anywhere in the world.

Difference between AMS NET ID  and IP address are here

AMS net id is a special type of identifier that is used in Beckhoff PLC to identify a PLC in the network. The net id is formed from the MAC address, continue…


HTTP TCP IP and TwinCAT, Will be written soon…



Continue reading.

How to update CE device and the PLC program for Panel PC

We might need to update our PLC from time to time. There are few reasons why we need to update the Image and our PLC program. For example, if some feature is not supported to the old SW we might need to change it. We shall discuss step by step what needs to be done if we want to update the panel. Continue reading the article.

TF6280 TwinCAT EtherNet/IP Adapter

Adapter settings, In combination with a network-capable Beckhoff PC, the function TF6280 TwinCAT EtherNet/IP Adapter can be used to create an Ethernet/IP adapter. Continue 

TF6420 | TwinCAT 3 Database Server

The TwinCAT Database Server enables data exchange between the TwinCAT system and various database systems. For small applications it can be used via a configurator, without intervention in the existing program code. For complex tasks the Database Server offers a large library of PLC function blocks for maximum flexibility. SQL commands such as Insert or Select can be used directly from the PLC, for example. Continue reading the article.

TwinCAT 3 licensing

TwinCAT 3 consists of the TwinCAT 3 development environment (TwinCAT 3 Engineering, XAE) and the TwinCAT 3 runtime environment (TwinCAT 3 Runtime, XAR). The core of TwinCAT 3 Engineering (PLC programming) is royalty-free and can be installed on any number of development PCs. Various functions/development tools that go beyond pure PLC programming (TExxxx) as well as TwinCAT 3 runtime licenses (TCxxxx / TFxxxx) are chargeable, however. The price of TwinCAT 3 runtime licenses depends on the performance of the control computer employed. The performance is subdivided into so-called platform levels.   Continue the article.

How to add library to PLC project

This will describe how to create library for TwinCAT and how to add it to VS project

Beckhoff PLC and C++

What we can do with C++  in PLC structured text environment? How to use the powerful C++ module has been explained with the sample in this article. Continue reading the article at https://infosys.beckhoff.com/english.php?content=../content/1033/tc3_c/2407126539.html&id=253450185781233922.