Welcome to the second part of my ladder logic tutorial. In part 1 of the ladder logic tutorial, I introduced you to the very basics of ladder logic and to some basic instructions.
In this second part of the tutorial I will teach you how to solve actual problems with ladder logic and how to use it to build PLC programs. At the same time you will be introduced to several other ladder logic instructions:Set / Reset CoilsSet or Reset PrioritySet / Reset Function BlocksSR Function BlockRS Function BlockBuilding Logic with Ladder LogicLogic Gates with PLC InstructionsOR and AND GatesNOT Logic GateInterlocking with Ladder LogicLadder Logic Exercise 1: InterlockingOne [...]
A PLC counter is a function block that counts up or down until it reaches a limit. When the limit is reached the output is set.
The thing is that counting is in fact widely used in PLC programming. Often you will have the need to counts different things. An example of this could be to keep track of how many times a process has been completed. Or how many products has been produced.
Have you ever wondered what a SCADA system really is? How does it work? And why is it called Supervisory Control and Data Acquisition?
In this tutorial I will give you an introduction to SCADA systems and architecture, SCADA applications and programming. All the basics you need to know about SCADA systems.
Some of the most essential functions in PLC programming are the timers. Time in PLC programs is used almost everywhere from delaying the start of a motor to prolonging a signal. PLC timers are used exactly for that. Although they at first can seem confusing it doesn’t take a lot to understand how they work and how to use them.
When it comes to automation and manufacturing ISA-88 or just S88 is inevitable.
It is a standard for published by The International Society of Automation (ISA) that sets out models and terminology addressing batch control. The standard was published in an attempt to standardize and thereby making it easier for automation suppliers to integrate, communicate and configure batches. It is adopted by Europe as IEC 61512-1.
Today, the standard is used by most manufacturers and automation suppliers that deal with batch control. Especially productions of food and medicine utilizes if not the whole, then at least parts of the standard to keep track of their batch production.
Do you struggle with risk assessment? Safety in machinery is a very important, but often under taught area full of complicated terms from the ISO 12100 standard. This article will take you through a risk assessment example by using procedures and methods from ISO 12100 and the old ISO 14121-2.
Risk assessment is a way of finding risks and hazards in your machine design. All machine designers have to make sure their machines are safe for humans to operate. Eventually, it is our responsibility to find all the risks and then eliminate those risks.
Safety relays are a special type of relay you can use to build a safety circuit. Safety is a critical issue in machine design. It is crucial to have a good basic understanding of the principles behind safety relays and safety circuits.
With that said, safety often becomes a confusing matter because a lot of terminology is attached to it. All that terminology comes from the standards describing safety circuits, functional safety and thereby safety relays.
Do you know how to scale your analog input? Or wire your analog output?
Many people struggle with analog signals in PLC programming. The wiring and how to use an analog input or output in your PLC program can be tricky. Most often you will see digital example PLC programs and in my Structured Text Tutorial most of the examples are digital programs.
I’m writing this article because many of you wanted to learn how to use analog signals in PLC programming. Analog signals are used widely in PLC programs but also often used in a SCADA system. So how do you connect that 4-20mA analog transmitter to your PLC and use it in your PLC program? How do you scale an analog [...]
One of the official and widely used PLC programming languages is the Function Block Diagram (FBD). It is a simple and graphical way to program any functions together in a PLC program. Function Block Diagram is easy to learn and provides a lot of possibilities.
Did you know that most universities don’t have PLC programming courses?
To learn PLC programming you will have to either teach yourself through finding bits and pieces of various PLC programming resources online – or you can enter one of the online PLC Training Courses.
One of the best visual programming languages is a PLC programming language. It’s called ladder logic or ladder diagram (LD) and you can learn it very fast.
The smart thing about ladder logic is that it looks very similar to electrical relay circuits. So if you already know a little bit about relay control and electrical circuits, you can learn ladder logic even faster.
Welcome to the first chapter of my Arduino Tutorial for Beginners. In this chapter, you will learn the very basics of the Arduino platform so that you can start programming. I will teach you how to set up your computer and write your first program for the Arduino Uno board.
New to PLC programming? Here’s the starter kit that will teach you the basic fundementals of PLC programming.With its small size, user friendly software and low price the Siemens LOGO Starter Kit is absolutely perfect for beginners.
You can build ladder logic PLC programs and simulate them for free. This guide will show you how to download and install the popular RSLogix Micro Starter Lite and how to use the RSLogix Emulate 500 to simulate your ladder logic PLC programs.
Do you also struggle reading your own and other huge ladder diagrams?
The truth is, that even though ladder logic is an easy programming language for beginners, it can be very hard to read and understand. That’s why some consider Structured Text to be a better PLC programming language – and you can learn all about it in this tutorial.
You probably have heard about the Siemens S7-1200 PLC. It is the latest Siemens PLC and the best for learning. Get the Starter Kit with the programming software SIMATIC S7 TIA Portal and begin learning Siemens PLC programming. You can even control the S7-1200 PLC with your smart phone!
You may know the difference between normally open and normally closed contacts, but do you know where to use them? This article will teach you where to use normally open and where to use normally closed for inputs and in your PLC program. You will learn how to connect your PLC program with the physical PLC inputs.
Ladder logic symbols are the basic building blocks for ladder diagrams. Right here you will find all the ladder diagram symbols which are described in IEC 61131-3. The symbols are available for download in all formats and in a PDF-file.
I will start this article by making a confession:
When I develop a PLC program, I steal other people’s ladder logic.
I am stealing ladder logic examples for inspiration and solutions to my PLC programs.
From time to time you will be facing the same problem, when you do PLC programming with ladder logic. By looking at examples of ladder logic programs, you will be able to find a solution to your problem very fast. You may even find a smarter solution in the ladder logic examples than your own solution.
This is an introduction to PLC logic. You can use PLC logic to build PLC programs with simple electrical circuit diagrams. In this article, I will use combinatorial logic to build the functionality of a PLC program.
And to get as close as possible to real a PLC programming language like ladder logic, the PLC logic in this article will be contacts and relays in an electrical circuit.
The Siemens S7-200 PLC is a very popular choice when you start PLC programming. It is the cheapest PLC from Siemens, and it is very easy to begin programming. The Siemens S7-200 has a limited variety of functions, but it certainly also has a lot of advantages. With this article, you will be ready to start configuring and programming the Siemens S7-200 PLC.
Thermocouples are fast temperature sensors with a wide temperature range. You can get all different thermocouple types, and you have to choose the type of thermocouple suitable for your project. The thermocouple types have different temperature ranges and tolerances.
This is my guide on how to make an Ethernet cable. Often just referred to as a network cable or patch cable. Making your own Ethernet cables will not only cut down the price of your cables. You can also make the Ethernet cables in the exact length and with the exact wiring you need. Use this guide if you are making Ethernet cables for personal or professional use.
Profibus or Process Field Bus is a standard within field bus communications in the automation industry. A network for industrial computers made to withstand high amounts of noise. The two wire Profibus cable makes different network topologies possible, like the star, the tree and the line or a combination.
The basic architecture of a PLC is important to understand. It is crucial to know about the basic PLC hardware components that are inside PLC, because it will make your understanding of the PLC much easier. The hardware components are the physical building blocks of the PLC.
Now, that we know what hardware is inside the PLC, the next step will be to take a look at the software inside the PLC and how it runs. Every PLC has a scan time and a scan cycle. This is how the PLC and the software inside the PLC works. The scan cycle is the cycle of which the PLC gathers the inputs, runs your PLC program and then updates the outputs. This will take some amount of time often measured in milliseconds or ms. The amount of time it takes for the PLC to make one scan cycle is called the scan time of the PLC.
Before getting started with the PLC programming, let me illustrate some basic concepts about a PLC program.
If you know about the PLC scan time, you can start to explore how the PLC program works. Combinatorial logic gives you the basic understanding of how combining the two states – true and false with logic. The basics of PLC programming is combining logic. That’s why combinatorial logic can be a great way into PLC programming. Since the fundamentals of combinatorial logic and PLC programming are the same.