PLC Programming Tutorial – Ladder Logic Basics for Beginners

If you live in North America and you work in a factory environment, or even if you’re just looking into a production facility of some sort for a job that has a decent level of automated labor as compared to manual (human) labor, then you’re going to end up in an environment where PLC programming is used to aid in the automation process.

In the United States and the rest of the Western Hemisphere, the most common and popular software that you can use for PLC Programming is none other than Allen Bradley’s RSLogix 5000, one of the best premium automation software platforms.

But how do you use the software if you’ve never used it before?

Fortunately, there are numerous training programs out there (such as the one that I provide), and in this guide, we’re going to teach you a bit about the basics of programming with Allen Bradley’s PLC software.

What is the Difference Between RSLogix 500 and RSLogix / Studio 5000?

When you purchase PLC software, you’re going to have to buy a license. The main thing to consider is that if you’re going to buy the software, you need to know what kind of software you’re going to use. Most of them have a license key to unlock the full premium features.

However, you can download RSLogix 500 completely free, and if you are going to learn the software, you need to install a free one for learning purposes.

Eventually, you may want to get a full software license.

There are different tier levels that you can get when you download RSLogix 500, and each different version of the software that you download will require you to pay for a different license to unlock these features. Some people think that if they learn the basics that are available in the free RSLogix 500 software, that they’ll have troubles when it comes to the Studio 5000 or even the RSLogix 5000 software.

Despite the differences in the names of various tags and the user interface, you still learn the fundamentals of PLC programming from Rslogix 500 or RSlogix Micro, which is all that matters – and those are the same no matter which version of the software you use! The trick to programming PLC controls is that you understand the logical theory behind it.

The rest is just learning the differences between the software types which is compared to different versions of Windows like Windows XP, Windows 7, Windows 10, or even Mac.

Here are the main differences between the three software versions:

RSLogix 5 – is mainly a data type system with some tag features that supports ladder logic only & is memory limited based on processor sizing.

RSLogix 500 – is mainly a data type system with some tag features that supports ladder logic only. RSLogix 500 ladder only, it utilizes register according to memory addressing of the processor used in the control system.

RSLogix 5000 – Is a Tag-Based ControlLogix system that integrates well with old & new device technology & all four languages of PLC programming, ladder logic, structured text, function block, & sequential function chart. RSLogix 5000 is the name of the software from the beginning versions all the way to Version 20.

Studio 5000 – Is Rockwell Automation’s newest ControlLogix tag-based system that has recently changed the user interface slightly to better fit the Windows 10 environment & works very closely to RSlogix 5000 yet nothing like RSlogix 500 besides that logic patterns. Studio 5000 was created in version 21 & goes all the way through version 32 where they change the user interface.

It is important to note that Rockwell Automation has recommended software suits of software that fit together for large systems if you are getting depending on your needs.

Examples of Processor Used On Each Software:

RSLogix 500 – Micrologix, SLC 5/01, SLC 5/02, SLC 5/03, SLC 5/04, SLC 5/05
RSLogix 5000 – CompactLogix, L5, L6, L7, L8
Studio 5000 – CompactLogix, L5, L6, L7, L8

So What Exactly is Ladder Logic?

Ladder logic is a method of programming logic for PLCs. It is used to control the software applications, and the reason why they call it such is that the programming language isn’t a bunch of source code like other programming languages, but rather a method of diagrams that display the different programs in a ladder visual.

This feature makes it easier to read along with program so that there is a better solution for automation.

You can see two rails and a bunch of horizontal rungs, very similar to a real ladder.

Here is a simple example of some ladder logic so you can get a better viewpoint.

These diagrams are one of the most common forms of standardized PLC programming today, and it helps to make the programming simple and pretty easy compared to having to utilize a bunch of source code (like you would have if you were programming it in a different language like C++ for example).

Download The Ladder Logic PDF

The User Interface of Studio 5000

One of the main things you’re going to deal with no matter what PLC programming software application you use, is that the user interface. You may want to navigate around the PLC program that you’re using (such as Studio 5000) by looking around in the toolbar.

You’ll find that in Studio 5000, you’ll have the normal software menus, such as File, Edit, View, Search, Logic, Communications, Tools, Window, and of course, Help.

You’ll also see that you have the basics in almost every application that you’ve used if you’ve ever used a computer: Open, Save, Save As, New Project, and much more.

The more you work with programming using Allen Bradley’s software, you’ll learn how to use these things even more, and how to do them with ease. You may even be able to get better at using things like keyboard shortcuts so you can speed up your process!

How the Controller Organizer is Used

The main thing that you’re going to need to use in all RSLogix and Studio 5000 applications is the controller organizer. This is basically an explorer-style menu that shows you the different key sections that allow you to see and select the different tag databases that are created. It also shows you the different programs that are executed when the program is run in the controller organizer.

To make sure the controller organizer is open then you can always open the ‘View” tab & open it.

You’ll have things separated in the controller organizer such as tags, motion groups, Add-On instructions, and you’ll even have data types listed in a file-tree view.

These are necessary when it comes to PLC programming, and they all work in conjunction with one another in order to create the final running program for the machine you’re programming.

You’ll need to pay close attention to the “Tasks” folder, because it literally has all tasks that your PLC controller will be running. You’ll see different types of tasks and everything will run continuously. As soon as the program is finished, with the right PLC program in place (as long as there aren’t any bugs in your automation program), the program will loop and start over again.

Here is a basic overview of a Studio 5000 controller organizer.

Sometimes, you may end up having special tasks that are periodic depending on the machine you’re programming, as these often have a timer associated with it so it runs a certain step every so often.

For example, if you need to program a timer on a slicing machine, you may need the controller to run a few blank runs when no product is running through it to help clean and keep the blades sharp. Something like this will be done by using a timer function.

When you’re using these in fast-paced environments, things like this need to be understood so you won’t have problems when certain tasks are dropped due to the lower priority. The routines that you will use inside of the program will also matter greatly. These are the sections of the program that contain the code.

This may be written using ladder logic as defined above, or you can use an FBD (function block diagram), SFCs (sequential function charts), or even what’s known as structured text.

These different programming formats have different nuances and they need to be used depending on the software of the program and PLC you’re programming.

The four major programming languages in PLC programming are:

Ladder Logic
Structure Text
Function block
Sequential Function Chart

The most popular method that people use, however, is Ladder logic.

How to Use Ladder Logic and Create Rungs & Tags

When you are wanting to build your first ladder logic routine, you can use the Studio 5000 software to give two basic function instructions to your controller. These are XIC Instruction and OTE Instruction.

You’ll click on the canvas and choose to Insert a New Rung. You can also use the top menu at the top of the programming section as well.

Once you have the basic run in place, you can click and drag separate instructions onto the user interface, or you can use the icons in the explorer. Depending on what’s comfortable for you, you can choose either way to achieve the same result. What’s important is that you achieve the same final result.

I like to show users either way so that they can feel more comfortable, because, in different areas of PLC programming environments, one may be more time-efficient than the other.

Once those instructions are set, you can configure the tags that are going to be linked to the instructions. These are necessary for the program functions to run, and the instructions are operated as Booleans (also known as BOOLs), meaning they’re a true or false value.

They are often a binary value as zero or even the number 1, with 0 being low, and 1 being high.

In the image above, the bot “Start_PB” is of a value of zero at this time, but when it was pressed, it caused the bit ‘System_Enable” to turn on which is a value of 1.

This shows a binary system being used in a ladder logic format as we talked about, the bit is either a one or zero.

The best way to create these tags is to ensure that you label every one of these instructions.

This way you can click the instruction with the right mouse button, and create a new tag. You’ll want your tag in most cases to be set as a Local Tag with the type of tag set to “Base”, and you’ll want to have the data type set to a Boolean.

Make sure that your scope is set to PLC, and click the Create button, and you’re all ready!

How to Run Certain Routines

One thing that you need to understand is that with PLC programming, the controller needs to determine what routine to execute at certain time intervals.

This order is determined with the programmer and in most cases, the operations are programmed in sequential order, as it’s often easier. You can literally make the routines bounce around as necessary, but in most cases, it’s more understandable that after the main routine (the primary routine that a PLC program will run), you can add JSR instructions to point to other routines.

Many programmers actually learn about JSR instructions and how to write them in a sequence, so that they run in order. This also helps to keep things more organized so that it makes troubleshooting later on easier, and it’s easy to follow the control flow of your designed program.

View Our Full Ladder Logic Tutorial

How to Get the Right Training for PLC Programming

There are numerous ways that PLC programmers get their education when it comes to training with Allen Bradley’s PLCs. Each one of course has its pros and cons.

And you also need to know that when you end up doing things such as going to school, your company may not be willing to pay the thousands of dollars that will be necessary for you to do so.

PLC Programming doesn’t actually require a college degree, so specific training may be the best option for you, and you can always use one of my courses to do so as well, as I’ve made a living trying to teach people the right way to learn PLC programming and simplify it so everything’s easier to understand.

1. Going to College

Some universities like MIT and other technical universities may have training for engineering students where they’ll have a specific class for Allen Bradley PLCs. Of course, there are major disadvantages (but some good advantages) to this method of training.

Pros

You get to learn about various hardware and software programs.
The learning is done in a structured environment.
You can achieve a certification or actual degree in engineering.

Cons

This is one of the most expensive options, costing up to tens of thousands of dollars.
The program can take a long time to complete, and the Allen Bradley PLCs won’t be the main focus of the program.
These aren’t taught by industry professionals, but professors who may not have the hands-on experience (and teach by the books).

2. Certified Allen Bradley Courses

If you go through Rockwell Automation, you may be able to find a certified partner that can train you in the ways of PLC programming. These are often at a distributor location, and they can literally take a few days up to a few weeks, depending on how in-depth these courses are. If you need to learn a certain course, these are more costly as well, and a lot of times a specific employer has to be the one to send its employee on these courses.

Pros

You get an official Allen Bradley certificate.
This method, like college, is done in a structured environment as well.
You get hands-on experience with the hardware and the programming software.

Cons

This is generally expensive compared to other third parties and may cost a lot of money for employers.
This method of training is often fast-paced and you may not retain all of the information, or not get the hands-on training for your specific company’s logic controllers.

3. Third-Party Allen Bradley Courses

This third method is one of the final options, but it’s a lot cheaper and is on a self-pace learning curve.

This means that you can control how quickly you want to learn and get certified for the Allen Bradley software. A lot of times, this method of learning is better for engineers at a specific company, because the right trainer will be able to teach you what you need to know in terms of basics, but they’ll also be able to tailor the training to your companies machines, as well as the programming that you’ll need and give you the hands-on training that you should have in order to be a better asset to your employer.

There are downsides, but if you use the free software as mentioned above, you can learn the same thing that you would if you were going through a college or training course.

Pros

This is a much cheaper option for PLC programming training.
You can learn at your own pace rather than have to deal with stressful situations that college or employer-based training will take place.
You get real training from true pros in the industry, who often has experience in the industrial automation industry.

Cons

You don’t actually get the full versions of the Allen Bradley software. Of course, you can download the free software, and sometimes get discounts or special deals if you sign up with the right trainer.
You don’t get a formal certification, but you get hands-on experience. If you wish to test to get formal accreditation however, you can always do so.

How My Training Helps

As mentioned above, getting the training from a third-party provider is the best way to do so. In my course, you can learn the most basic skills that will help you learn PLC programming, and when you are learning with my course, you can even get in-depth hands-on experience that can show you advanced techniques as well to help maximize efficiency and productivity.

You can utilize the course to teach you everything you need to know, then go yourself (or if your employer is willing to pay for the testing), get the certification that you need to become an accredited PLC programmer! You can even use all of these automation methods that I teach to other applications and industries in which automation can enhance and increase your skills as well. This is something you can’t always achieve with other programming courses.

If you’re wanting to learn the best way possible, you can learn the easiest way to understand by choosing my course and getting the right certification.

You’ll even get video training courses that show you every step of the way.

Ladder Logic Basics for Beginners

If you live in North America and you work in a factory environment, or even if you’re just looking into a production facility of some sort for a job that has a decent level of automated labor as compared to manual (human) labor, then you’re going to end up in an environment where PLC programming is used to aid in the automation process.

In the United States and the rest of the Western Hemisphere, the most common and popular software that you can use for PLC Programming is none other than Allen Bradley’s RSLogix 5000, one of the best premium automation software platforms.

But how do you use the software if you’ve never used it before?

Fortunately, there are numerous training programs out there (such as the one that I provide), and in this guide, we’re going to teach you a bit about the basics of programming with Allen Bradley’s PLC software.

What is the Difference Between RSLogix 500 and RSLogix / Studio 5000?

When you purchase PLC software, you’re going to have to buy a license. The main thing to consider is that if you’re going to buy the software, you need to know what kind of software you’re going to use. Most of them have a license key to unlock the full premium features.

However, you can download RSLogix 500 completely free, and if you are going to learn the software, you need to install a free one for learning purposes.

Eventually, you may want to get a full software license.

There are different tier levels that you can get when you download RSLogix 500, and each different version of the software that you download will require you to pay for a different license to unlock these features. Some people think that if they learn the basics that are available in the free RSLogix 500 software, that they’ll have troubles when it comes to the Studio 5000 or even the RSLogix 5000 software.

Despite the differences in the names of various tags and the user interface, you still learn the fundamentals of PLC programming from Rslogix 500 or RSlogix Micro, which is all that matters – and those are the same no matter which version of the software you use! The trick to programming PLC controls is that you understand the logical theory behind it.

The rest is just learning the differences between the software types which is compared to different versions of Windows like Windows XP, Windows 7, Windows 10, or even Mac.

Here are the main differences between the three software versions:

RSLogix 5 – is mainly a data type system with some tag features that supports ladder logic only & is memory limited based on processor sizing.

RSLogix 500 – is mainly a data type system with some tag features that supports ladder logic only. RSLogix 500 ladder only, it utilizes register according to memory addressing of the processor used in the control system.

RSLogix 5000 – Is a Tag-Based ControlLogix system that integrates well with old & new device technology & all four languages of PLC programming, ladder logic, structured text, function block, & sequential function chart. RSLogix 5000 is the name of the software from the beginning versions all the way to Version 20.

Studio 5000 – Is Rockwell Automation’s newest ControlLogix tag-based system that has recently changed the user interface slightly to better fit the Windows 10 environment & works very closely to RSlogix 5000 yet nothing like RSlogix 500 besides that logic patterns. Studio 5000 was created in version 21 & goes all the way through version 32 where they change the user interface.

It is important to note that Rockwell Automation has recommended software suits of software that fit together for large systems if you are getting depending on your needs.

Examples of Processor Used On Each Software:

RSLogix 500 – Micrologix, SLC 5/01, SLC 5/02, SLC 5/03, SLC 5/04, SLC 5/05
RSLogix 5000 – CompactLogix, L5, L6, L7, L8
Studio 5000 – CompactLogix, L5, L6, L7, L8