The Blog

This month’s topic is Discrete I/O vs Analog I/O.

If you’ve delved into PLCs at all, you should know what PLC inputs/outputs (I/O) are. But here’s a quick refresher...

PLC I/O is the part of the PLC that connects the brain of the PLC (the CPU), to the outside world, the machines, the switches, the push-buttons, etc. In a PLC system there will usually be dedicated modules for inputs and dedicated modules for outputs.

An input module detects the status of input signals such as push-buttons, switches, temperature sensors, etc.. An output module controls (turns on/off, ramps up/down, etc.) devices such as relays, motor starters, lights, gauges, etc.

Discrete/digital I/O is either on or off (think light switch on or off). Analog I/O can be on or off or in between (think light switch dimmer). 

The inputs tell the PLC what to do with the outputs (depending on how you've programmed the logic).

We are all familiar with computer I/O (you're using it right now)....

One of the questions I get a lot, is how to connect from your computer to a PLC. This is foundational to getting confidence with PLCs, so I decided to make short video series to show you how to get it done.

This video will walk you through the basics for communicating with ANY Allen-Bradley PLCs.

CONNECTING TO ALLEN-BRADLEY PLCS INTRO

Prefer to read it? Go Ahead…

Hey there guys, it's Stephen Gates with my PLC training.com with another video here to help you become a confident PLC programmer.

So one of the biggest questions or most common questions I get from people is how to connect from their computer to a real PLC so they can download or upload the program or just go online and see what the controller sees. So I'm going to do a short video series on the steps on what you need to connect your computer to an Allen Bradley PLC. So let's jump right into it.

So before we get officially started, I wanted to let you know about a free cheat sheet I have where I can show you...

This month we have another PLC training article to help you become a confident PLC programmer

The theme is…

Studio 5000 Logix Emulate

This software is key if you want to learn/practice Allen-Bradley PLC programming anytime and anywhere and don’t want to have to buy an expensive PLC to lug around (granted the software is expensive too, but I have a solution for that ;)). 

This tool is extremely valuable and will even help you with testing, simulating PLC logic for real projects.

Here’s how it works:

Logix Emulate gives you the ability to turn your computer into a PLC. So it takes a chunk of your computer’s power and makes it function almost exactly like a ControlLogix PLC controller, such as the 1756-L71 controller.

I think this is one of THE best tools for helping you learn PLC programming and that’s why we include access to this software in myPLCtraining Academy. But more on that later…

Setting up a Studio 5000 Logix Designer...

This month’s blog post topic is all about sending messages between PLCs. Specifically Allen-Bradley PLCs, such as ControlLogix and CompactLogix controllers.

This is actually pretty cool and a fun topic to learn.

Here’s a simple example of why you’d want to communicate data from one PLC to another.

Let’s say PLC 1 controls one steam boiler and PLC 2 is the main plant PLC that monitors the alarms all the boilers in the plant and other equipment as well.

Think of PLC 2 as the Plant SCADA PLC that allows an operator in the main control room to get an overall look at the plant from his control room.

So let’s say we want to send data from PLC 1 such as the most important boiler temperatures and pressures so that we can display them on the control room HMI screen. 

If these are Allen-Bradley PLCs (ControlLogix, CompactLogix), the best way to do this is usually to use Ethernet. Specifically EtherNet/IP.

Here’s a simple image of how the two...

I’m excited about the topic of this article, which is….

Structured Text!

Structured Text is an up and coming, popular programming language used in PLCs. This language is much different than ladder logic but it allows you to do all the same things and more with a lot less space (visually and in terms of processor memory). 

It’s been around for a while but it’s getting really popular now, so it will serve you well to at least have a basic familiarity with it.

It’s actually a lot like other more traditional programming languages out there like C++ or Java but it’s specifically designed for PLCs. 

Here’s an example of a really simple Structured Text program in an Allen-Bradley PLC (Studio 5000 Logix Designer):

IF Start_PB THEN

Motor_Run_Relay := 1;

END_IF;

IF Stop_PB THEN

Motor_Run_Relay := 0;

END_IF;

The logic above turns on the Motor_Run_Relay output when the Start_PB input is on (being pushed) and it turns off the...

If you're serious about becoming a confident PLC programmer then you have probably heard of Modbus. And if you haven't...that's ok because you are about to.

Modbus is an old industrial communications protocol that allows for the transmission of data among PLCs and/or other industrial devices. 

Believe it or not, this protocol has been in use since 1979!

It has obviously stood the test of time. This is most likely because of how simple it is to use and the fact that it is open source. Meaning company or individual can build-in Modbus communications into their PLC products or other industrial devices 

For example, let’s say you have basic building thermostat that you need to connect to your PLC, (there are some thermostats available with Modbus). Let’s say you need to monitor the temperature in the room and display it on an HMI screen. 

Also let’s say we want to be able to see when the thermostat is calling for heat or cool. 

If the...

I have been getting a lot more requests from people who not only want to learn PLCs but also need to learn how to set up HMIs to talk to PLCs. 

PLC logic programming is really just one piece of a bigger puzzle. It's a very important one but you need to learn some other skills along with it if it's going to prove useful in your career.

In this article we will be covering HMI programming and design. Particularly HMI programming and design with FactoryTalk View software.

Since we focus our training on Allen-Bradley/Rockwell automation products, FactoryTalk View is the HMI software that we know and teach our students.

FactoryTalk View is very powerful, but also pretty easy to use if you’re just getting started.

If you want more resources to learn FactoryTalk View after you read this article check out the link below to get a free PDF I create for you.

But let’s back up a minute and clarify what an HMI is…

What is an HMI?

HMI stands for Human-Machine...

If you want to learn PLCs, you absolutely need to learn Ladder Logic. I've got an epic post for you today to tell you everything you need to know to get started on your PLC training journey by learning Ladder Logic.

Here's what I've got in store for you:

• An Introduction to PLC Ladder Logic (3 most important instructions)
• Video Walk-Through of a real Ladder Logic program in Studio 5000 (relay-type instructions, timers, counters and more)

Introduction to Ladder Logic

Ladder Logic is a programming language that PLCs have been using in some form since the ’70s. Now, it’s gone through some changes over the years but is still very popular and heavily used in manufacturing and industrial automation.

Nowadays, there several other programming languages available for PLCs/PACs but Ladder Logic is still really popular for a few reasons.

1. It's been the industry standard for many years.
2. It’s easy to learn and implement because it works like electrical control circuits...

In this post, I’m going to be sharing about Rockwell’s flagship PLC/PAC programming software called Studio 5000 Logix Designer.

This software used to be called RSLogix 5000 and if you’re serious about learning PLCs to advance your skills and career you’ll likely be using this software a lot.

You’re going to need to get really comfortable with this software if you’re going to prove to employers/bosses that you have what it takes to be automation/controls technician. So, I highly recommend that you focus on PLC training that focuses on Studio 5000.

We will be breaking down this software in quite bit in this post, but to start I wanted to do a quick overview of what the software does.

• Logix Designer is where you will create all your programming logic for your PLC automation.
• This software is used to program ControlLogix and CompactLogix controllers and is also used for programming the Studio 5000 Logix Emulate controllers, which are software...

A while back I was talking to guy named Mark about myPLCtraining Academy and he told me something pretty cool.

Mark had recently transitioned from electrician to controls technician...without getting a degree or even a special certification.

He had been making a good salary of about $80,000 as a maintenance/industrial electrician, but now that he’s been promoted, he’s making up to $100,000!!

And that’s just his starting salary as a controls tech. It will certainly go up from here.

Since I’m  dedicated to helping electricians do exactly Mark did, I had to know more...

Turns out Mark had been with his company for quite a few years as an electrician but over time he kept trying to learn more about automation. He eventually took one PLC class at a tech school and soon after was promoted.

Now he’s been promoted, is doing controls and automation work which he really enjoys and less back-breaking work, and is making up to 20% more each...