Can microcontrollers replace PLCs?

Microcontrollers cannot completely replace PLCs. Although microcontrollers can achieve similar functions 

through programming, they are relatively inferior to PLCs in terms of reliability and stability.

PLC has good programmability, real-time performance, and stability, and is widely used in industrial control 

and automation fields.

Compared to microcontrollers, PLCs have the following advantages that make them unable to be replaced 

by microcontrollers in certain applications:

1. High reliability: PLC adopts industrial grade components, which have reliable and stable performance. 

Its internal mechanism design is complex, precise, and stable, so there are rarely situations such as crashes 

or blue screens, and it has a long service life.

2. Strong anti-interference ability: PLCs usually have stronger anti-interference ability and higher stability

and can work in more harsh environments such as high temperature, high humidity, strong electromagnetic 

interference, etc.

3. Modular and distributed control: PLC can build complex systems through modular and distributed control 

supporting multi task processing and multi device collaborative control.

4. Simple programming: PLC programming is relatively simple, often using graphical programming languages 

such as Ladder Diagram, Sequential Function Diagram (SFC), Structured Text (ST), etc. This shortens the 

development cycle and reduces the difficulty of development.

5. Flexible input and output interfaces: PLCs usually have a large number of input and output interfaces

which are easy to expand and use. In addition, PLCs also have good multi-channel control functions, allowing 

direct operation of input and output operations.

6. Strong scalability: PLCs can add functionality through module expansion without the need to modify the 

PLC itself.

7. High security: PLCs usually have high security and can ensure the safety of the system through security 

modules and protocols.

What is the difference between PLC and microcontroller?

1. PLC is a relatively mature control system composed of single-chip microcontrollers, and is a product of a 

mature and stable single-chip microcontroller application system that has been debugged. Has strong 

universality.

2. And microcontrollers can form various application systems with a wider range of uses. As far as the 

"microcontroller" is concerned, it is just an integrated circuit that must be combined with other components 

and software to form a system for application.

3. From the perspective of engineering usage, for single projects or projects with very few repetitions, using 

PLC is fast, convenient, has a high success rate, and good reliability, but the cost is relatively high.

4. For large-scale supporting projects, using a microcontroller system has the advantages of low cost and 

high efficiency, but it requires considerable research and development strength and industry experience to 

make the system stable.

Essentially, PLC is a pre built microcontroller system. The development engineer designed a simple 

programming system for PLC and developed supporting programming software, replacing the basic 

programming language of computers with a simple programming language, greatly simplifying application 

programming.

PLCs widely use programming languages such as ladder diagrams, statement tables, and function blocks 

instead of computer languages, which have certain advantages in programming. You can understand ladder 

diagram as a programming language similar to assembly and other calculator languages, just with a different 

scope of use! And the usual practice is for PLC software to convert your ladder diagram into C or assembly 

language, and then use assembly or C compilation system to compile it into machine code! PLC only runs 

machine code. The ladder diagram makes use easier, reduces user requirements, and shortens the 

development cycle.

Of course, it is also possible to directly develop control systems using microcontrollers, but the requirements 

for developers are quite high (not something that a general level can handle). Firstly, a certain language 

foundation in C or assembly language is needed. Secondly, familiarity with electronic circuits and hardware 

is required, as well as a long period of programming experience accumulation. Even an experienced engineer 

needs to design circuits, write programs, conduct experiments, start mass production, and make 

modifications and maintenance based on feedback from industrial sites in order to gradually stabilize. 

The development cycle is long and the cost is high.

From this, it can be seen that in order to learn PLC programming, one only needs to systematically learn the 

application of PLC programming instructions and advanced functions such as interrupts, high-speed 

counting, high-speed pulses, communication, and analog quantities. With some on-site experience, one can 

quickly independently complete the design of small projects. For those who want to engage in industrial 

automation programming, learning PLC is the best choice.

Overall, microcontrollers and PLCs differ in terms of application, functional implementation, structure

interface, reliability, stability, cost, and programming debugging. In practical applications, it is necessary to 

choose a suitable control system based on specific needs and conditions.