With the rapid development of industrial computer performance and the improvement of its reliability, coupled with the reduction in its price, industrial computers have become more and more widely used in the field of process control and automation. It has high reliability, real-time response processing, easy expansion, rich digital, analog and switching input and output interfaces, and can adapt to the harsh industrial field environment and other advantages.
Programmable logic controller (PLC) is a new generation of industrial control devices developed in the 1970s. It is widely used in various fields of industrial control. It is based on relay logic control and gradually develops into both logic control and counting and timing. , Branch program mathematical calculation, analog quantity, pulse control and other comprehensive control devices. From the perspective of hardware, PLC is actually a special computer with an interface suitable for industrial control.
The differences between industrial computer and PLC are:
1. Hardware structure. Industrial control computer and PLC are composed of central processing unit CPI, memory, input and output equipment, etc. PLC is a dedicated calculator, but it has a different bus architecture from industrial control computer.
2.Cost-effective. Industrial computer and PLC have the characteristics of high performance, high integration, modularization, mass production and wide application. When the design of the control system does not have more complex data processing, graphic display or motion trajectory requirements, the use of PLC can get better cost performance. So the general ordinary pipe bender can meet the requirements with the integrated PLC. Its control cost is also relatively low, otherwise it can only choose a control system composed of industrial control computer + board or industrial control computer + PLC.
3. Peripheral configuration. Industrial control computer has richer external equipment than PLC, such as display, driver, printer, network interface card, etc., and are all standard components. Peripherals generated by different manufacturers can be used as long as they are equipped with corresponding driver software. The PLC has fewer types of peripherals and strong specificity. Different brands of peripherals are not universal.
4. Human-machine interface tools. The touch industrial display is a tool that connects humans and PLCs. It can be used for parameter setting, data display, curve, animation and other forms to depict the automation control process, and it can simplify the PLC program. Compared with traditional analog instruments and button operation consoles, it has a smaller volume and simplified control wiring.
5. Programming tools. For industrial computers, you can use advanced languages such as C programming to make the written applications easy to modularize and run logically, but the software preparation time is long, debugging assistance, software programmers need to have high knowledge of software and hardware, and PLC Ladder diagram is adopted, the software and hardware development cycle is short, and it is easy to maintain and troubleshoot.