What is an Open PLC?

To program a PLC, I need to write a program on my computer and download it to the PLC.

To be able to write the program on my computer, I need programming software, right? I can not just open up my laptop and start writing codes.

For example, to write code in C++ on my computer, I need to have a software programming editor such as Visual Studio.

This programming software editor gives me the ability to write codes in C++ on my computer. In fact, Visual Studio works as a container on my computer to hold my codes.

Programming a PLC is no different. To write a PLC program on my computer, I first need to install programming software to be able to start writing the codes.

Let’s say that I have three PLCs. For the sake of simplicity, I’ll call them PLC A, PLC B, and PLC C.

PLC A can only be programmed with software A, PLC B can only be programmed with software B, and PLC C can be programmed with software C but can also be programmed with software D and software E.

What is an open PLC?

So PLC A can only be programmed with software A. That means to program this PLC, I need to have software A installed on my computer to be able to start writing codes! Because I can only use software A for programming, I call this a closed PLC.

The same goes for PLC B. This PLC can be programmed only with software B. So this one is also what I can call a closed PLC.

But things are different for PLC C. Unlike the other two PLCs, this PLC can be programmed with software C but it can also be programmed with software D and software E. This is what we call an open PLC.

An open PLC is a new type of PLC that is not limited to only one programming software and can also be programmed by some other programming software as well.

Examples of Open PLCs

You can consider PLCnext from Phoenix Contact as an open PLC. The main programming software that can be used for programming this new PLC is PLCnext Engineer.

But in addition to that, this PLC can also run programs created by other programming software such as Visual Studio or Eclipse. Visual Studio and Eclipse are programming software that can be used to write code in C++.

Advantages of open PLCs

Now you may ask, so what? What is the advantage of an open PLC? What can I do with this PLC that can not be done with a classic closed PLC?

Well, the main advantage of an open PLC compared to a closed PLC is that, given the flexibility, you are able to run this PLC using higher-level programming languages such as C++.

For example, going back to the initial example that we had at the beginning of this article, for PLC A, I can only use software A for programming and since this is a classic PLC, software A only supports typical PLC programming languages such as ladder logic, function block diagram, and structured text.

The same goes for PLC B as this is also a closed and classic PLC.

But for PLC C, I can use software C to program this PLC using the typical PLC programming languages. I can also use software D and software E for other high-level programming languages such as C++.

For example, with PLCnext, I can use PLCnext Engineer to write code in typical PLC programming languages such as ladder logic, function block diagram, and statement list and I can use Visual Studio or Eclipse to write codes in C++.

Using C++ I can write programs that I may not be able to write using typical PLC programming languages. So the advantage of an open PLC is more flexibility and more options compared to a classic closed PLC.

Conclusion

An open PLC is a next-generation type of PLC that is not limited to only one programming software. It can incorporate higher-level languages programmed by other programming software as well.

This gives us more flexibility when it comes to using other programming languages to program a PLC.

I hope this short article helped you better understand this new concept of open PLC. If you want to learn more about this new technology, I suggest starting by taking the free course on PLCnext configuration and programming basics on RealPars if you haven’t already.

Once you complete this basic course, you’ll be ready to dive even further into the world of open PLC by taking the PLCnext ladder logic programming and then Using C++ project with PLCnext.

As a reminder, by completing these courses you’ll receive a certificate of completion signed and approved by Phoenix Contact.

‍