PLC
Programmable Logic Controller (PLC) is a specialized computing device, the introduction of microelectronics technology, computer technology, automatic control technology and communication technology on the basis of the traditional sequential controller and the formation of a new generation of industrial control devices, the purpose of which is to replace the relays, implementation of the logic, counting, and other sequential control functions, the establishment of a flexible remote control system. It is characterized by strong versatility, ease of use, wide adaptability, high reliability, strong anti-interference ability and simple programming.
They were originally developed to replace hard-wired relays and timers used in work processes in the automation industry, but today they have been scaled up and are in use in manufacturing processes across a wide range of industries, including robot-based production lines. Today, PLC devices are used in most factories around the world. This is mainly due to their stability and durability to withstand rough handling and high intensity vibration environments.
Microcontrollers
Microcontrollers are small computing devices on a single chip that contain one or more processing cores, memory devices, and general-purpose input and output (I/O) ports. They are used in a variety of everyday devices, especially in applications where only specific repetitive tasks need to be performed. Unlike PLCs, they do not have interfaces like displays or built-in switches; they can only connect these external components using interfaces like GPIOs.
Architectural Components
PLC Architecture
A PLC can often be referred to as an advanced microcontroller. It is composed of a power supply component, a microprocessor CPU and memory component, and an input/output component. The processor module consists of the central processing unit (CPU) and memory. In addition to the microprocessor, the CPU contains at least one more interface through which it can be programmed as well as a communication network. The power supply is usually a separate module and the input and output modules are separate from the processor. The input/output module may also contain modules for externally connected devices.
1. Microcontroller Architecture
The microcontroller is somewhat similar to the PLC described above, but the microcontroller integrates the CPU, memory, storage units, and the input/output ports and interfaces needed to communicate with the outside world onto a single chip.
2. Interfaces
PLCs are designed for industrial use, and their operating environment is usually incompatible with microcontrollers without peripherals. Microcontrollers can basically do what PLCs can do in terms of functionality, and industrial designs usually have to deal with hundreds of inputs and outputs. Although the microcontroller can be solved by adding peripherals, but the relative cost and instability.
3. Performance, Stability, Reliability
These are the three things that set PLCs apart from the rest; PLCs are designed for industrial needs and therefore can withstand industrial production conditions such as temperature variations, noise, handling and vibration.
Microcontrollers are different. By design, they were not originally designed to be used as standalone devices such as PLCs. Microcontrollers are designed to be embedded in a system, so the appearance of a microcontroller is all about simplicity. Microcontrollers can fail if we are not careful in their use, and the chips themselves are fragile and easily damaged.
4. Requirements for use (simplicity)
PLC programming requires low technical knowledge, as well as the use of building block structure, flexible configuration and easy to install. PLC is not complicated to use, only need to receive formal training in the use of factory technicians will be able to operate, troubleshooting and diagnosis is relatively easy. Nowadays, PLC is basically with liquid crystal display, the operator can monitor through the liquid crystal.
Microcontroller requires proficiency in chip knowledge. Developers need to be proficient in the hardware part and programming knowledge to design circuits. Microcontrollers also require special tools (e.g. oscilloscopes) for troubleshooting and fault-finding. Although there are several integrated and simplified platforms like Arduino, comprehensively from the point of view of simplicity, microcontroller is much more demanding on personnel than PLC.
5. Application
PLC is very commonly used in industry, it is used for controlling production, production management etc. Microcontrollers are widely used in everyday electronic devices. They are a major component of smart devices and consumer electronics.
To summarize
Microcontrollers are not designed to work stably under extreme conditions like PLCs, which makes microcontrollers unsuitable for industrial applications. Industrial devices are designed in accordance with the standard, microcontroller may not be able to support, if you insist on using the need to add peripherals, it will increase the cost and increase the risk of damage, which is not in line with the nature of industrial products.
In summary, each of the industrial control devices is designed for a specific system, and their factors should be fully considered when deciding to select a specific application as the best device. It is worth noting that some manufacturers are building microcontroller-based PLCs, and there are now PLCs built on Arduino, and in the future perhaps microcontrollers can be used in industry on a wide scale, and it is not yet time to reach a replacement.