People need to remember that parts of a Programmable Logic Controller system can be categorized as the following: Central Processing Unit (CPU) or processor, Input, and output. In this article, we will discuss how the Central Processing Unit – where the PLC memory, as well as the logic, is found.

Programmable Logic Controller and the human brain

The Central Processing Unit is considered as the center of the system. It can be compared to our brain (just not nearly as complex). That is why in this article, we are going to use the brain as an example to help us understand why CPUs are essential to the process.

It is the home for memory, communication, and PLC logic. Similarly, the neurologic center of our body is the source of the human logical decisions, communications, and memory that help our body connect with each part or other brains.

Logic

The Central Processing Unit is where Programmable Logic Controller (usually programmed with the use of ladder logic) is stored. These programs are created by developers to help automate the entire machine setup of industrial plants or process facilities.

Programmed logic in the PLC Central Processing Unit can be compared to the human brain in a way that the brain will take input signals like sound, taste, smell, feel, or sight and produces output actions like talking, gripping, reaching or stepping based on the human brain’s programming.

For more information about CPUs, check out https://en.wikipedia.org/wiki/Central_processing_unit for more details.

Obviously, this analogy breaks down sooner or later since the programming or logic in the brain is not fixed; it is continually adjusting to new teachings and experiences. Traditionally, this system has been programmed to be used using Ladder Logic exclusively. A lot of more modern PACs also allow users to process with other languages like Structured Texts, Sequential Function Charts, Function Block Diagrams, as well as Instruction Lists.

Memory

The memory is usually found in the Central Processing Unit and is where PLC data, as well as vital programs to run the system, are stored permanently or temporarily; it is similar to the memory of the computer Random-Access Memory or RAM and Read-Only Memory or ROM. Again, this can be compared to the brain, which shares vital information permanently and temporarily. It enables users to achieve different tasks like eating or riding a bicycle – it is all muscle memory.

Communications

PLC processors handle some form of communication. Communications from PLC CPU generally include one or more of the following:

Communications through USB or Universal Serial Bus ports on the CPU module to the computers.

Communications to the I/O or Input and Output modules using the chassis backplane

Communications to different Programmable Logic Controllers, as well as other automation devices through the Internet and other network types.

Continuing with the brain analogy, PLC communications can be prepared to help appropriately communicate from the programmer like God, teachers or daily experiences, to the human brain, communication from the neurologic center of our body to different body parts like legs, hands, nose, or eyes and connection between other minds (communicating with other people). If we take closer at this analogy, the brain’s logic can look something like this:

It receives input from the nose that something is burning in the kitchen.

It will make a logical decision as to why you should turn off the burner.

It will tell other parts of your body like your eyes, arms, and legs to go to the kitchen, turn off the burner, hold the pot or the frying pan, and put it in a safe place.

Although our brain is more complicated, adaptable, and powerful compared to PLCs, you can see some similarities between the two control systems. Specifically, people should be able to see the similarities between the brain and the PLC CPU. Notice how Programmable Logic Controllers can be programmed to work with every mechanical and electrical equipment to perform a lot of tasks that would otherwise have been manually done by humans.

Allen-Bradley PAC and PLC processors

The focus of this PLC training article is to help introduce users to what this system is, as well as the purpose of different parts of the process. As we all know, there are differences between Programmable Logic Controllers and Programmable Automated Controllers. We also know that the definition of both systems differs from person to person. But most of these concepts in the series apply to both PACs and PLCs.

Conclusion

So, you made it this far in this article, nice work. There is still a lot to learn about PLC, and sometimes it feels like there is information overload as you deep-dive into it. In this industry, there will always be a lot to learn, but at this point, users should have a better understanding of what these PLC processors are for.

They should be able to see what human brains can teach us about Programmable Logic Controller processors, as well as be familiar with processors and its components. This system is fundamental to a lot of industries like medical, construction, hospitality, manufacturing, Information Technology, Electronic, Pharmaceutical, Entertainment, Agriculture, or Transport Industries.

These are the cores of our livelihood; that is why people need to learn more about it. PLCs and PACs are the future of innovation; make sure you learn everything there is to learn to get an advantage over the competition. We are in a world where automation is needed to provide better products and services. That is why it is necessary to learn more about the brains behind this automation process.