In the world of industrial automation, the mention of PLC programming, most of the old drivers will smile meaningfully: "This is the guy who eats." But the novice white is often confused: "PLC is what? Programming and what the hell?" Today, we will unveil the mystery of this legendary PLC programming, so that you can also be transformed into an old driver of PLC programming!
What is PLC programming anyway?
PLC, full name is "Programmable Logic Controller", that is, programmable logic controller. Simply put, it is a special computer for industrial control, responsible for receiving a variety of input signals, in accordance with the set logic for processing, and then control the output.PLC's existence is to make those complex industrial equipment obediently in accordance with the procedures we set up to run.
But, PLC programming is still a bit different from regular programming. While regular programming might be more about messing around with websites, apps, and whatnot, PLC programming deals with all kinds of machinery and equipment, big and small. It's code that is mainly used to control industrial processes like robot arms on assembly lines, starting and stopping production equipment, and so on.
PLC programming: writing instructions to the machine
When it comes to programming, the first reaction of many people is to knock the code, as if only the dense characters can reflect the depth of programming. However, PLC programming is another picture.
PLC programming usually uses several specific languages, and don't look at the lofty names, they are actually quite grounded:
1.Ladder Logic ：This is one of the most classic languages in PLC programming. Ever seen a circuit diagram? A ladder diagram looks just like a circuit diagram, like a ladder, with each rung of the ladder being a piece of control logic. It's especially good for those with a background in electrical engineering because you can directly translate the logic on a circuit into instructions on a ladder diagram.
2.Function Block Diagram, FBD ：It's a more graphical language, with various "blocks" representing different functions. Like building blocks, you just need to connect them together and the system will work the way you want it to. This language is particularly suitable for engineers who like to work with their hands and don't like long pieces of code.
3.Structured Text, ST ：If you come from the world of high-level programming languages, such as C, then ST is for you. It allows you to write programmes in a way that is close to natural language, so you can implement complex control logic in more concise code.
Let's get real: how does a PLC work?
Talking about the theory is easy to let people in the clouds, to some practical to see how the PLC works. PLC operation can actually be divided into three steps: input processing, logic processing and output processing.
input processing
Firstly, the PLC receives signals from sensors, buttons or switches. These signals can be a change in voltage or a change in the state of a switch (e.g. a button being pressed.) The PLC converts these signals into digital data, which is the "raw material" we are dealing with.
Logical Processing
Next, the PLC will run its internally stored programs to process this input data. These programs are actually logic instructions that we have written in various PLC languages.Based on these instructions, the PLC will decide what to do next. For example, if a sensor detects that the temperature exceeds a certain threshold, the PLC might instruct the cooling system to start.
Output handling
Finally, the PLC will control the output devices based on the processed results. These output devices can be motors, lights, valves, etc. That is, the PLC will control the behaviour of these devices by sending out electrical signals. For example, if the programme instructs to open a valve, the PLC will send a signal to cause the valve to perform the switching operation.
Why PLC programming is so important?
Now you may be thinking, "Doesn't PLC programming just sound like giving commands to a machine? Why is it so important?" Don't worry, take a look at its application scenarios and you'll understand.
Industrial manufacture
In an automotive manufacturing plant, PLCs control countless robotic arms that precisely weld the body and mount parts with little to no error. Without PLCs, these complex operations would simply not be possible.
Energy administration
In the energy industry, PLCs are used to manage power distribution and equipment operation. For example, in power plants, PLCs control the starting and stopping of generators to ensure stable and safe power output.
Food production
In the food and beverage industry, PLCs control the operation of the entire production line, from mixing ingredients to packaging, all steps with precision and accuracy.The efficient control of PLCs not only improves production efficiency, but also ensures the quality of the product.
The future of PLC programming: towards intelligence
As technology continues to advance, PLCs are also evolving. From its humble beginnings as a simple controller to its highly intelligent capabilities, PLC is moving towards convergence with the Internet of Things (IoT) and Artificial Intelligence (AI).
IoT Integration
Modern PLCs can connect to a wide range of smart devices over the network to monitor and control the entire production process in real time. This connectivity enables PLCs to be better integrated into the Industry 4.0 ecosystem for data-driven decision-making and optimisation.
Edge computing
Edge computing refers to computing locally where the data is generated rather than transmitting it to a central data centre.PLCs are becoming smarter and smarter and can perform complex data processing and decision making locally, resulting in increased responsiveness and system efficiency.
PLC programming is not only a display of technology, but also an art. In the stage of industrial automation, PLC is the conductor, the programme is the sheet music, and various mechanical devices are musical instruments. Through PLC programming, we can command all this, playing a beautiful industrial symphony.
Becoming a veteran of PLC programming requires not only skill, but also a deep understanding and keen insight into industrial processes. We hope that through this article, you can have a new understanding of PLC programming and bravely embark on this journey full of challenges and opportunities.
