Advantages of PLC over relay circuit

2022-06-13
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Advantages of PLC over relay circuit

1 Strong function and high performance price ratio

there are hundreds of programming components for users in a small machine, which has strong functions and can realize very complex control functions. Compared with the relay with the same function, it has a high performance price ratio. Programmable controller can realize decentralized control and centralized management through communication

2. Complete hardware, easy to use and strong adaptability

programmable controller products have been standardized, serialized and modular, and are equipped with a variety of hardware devices for users to choose from. Users can flexibly and conveniently configure the system to form systems with different functions and scales. The installation and wiring of Leng programmable controller is also very convenient. Generally, the wiring terminal is used to connect the external wiring. PLC has strong load capacity and can directly drive general solenoid valves and AC contactors

3. High reliability and strong anti-interference ability

a large number of intermediate relays and time relays are used in the traditional relay control system. Due to poor contact of contacts, it is prone to failure. PLC uses software to replace a large number of intermediate relays and time relays, leaving only a small amount of hardware related to input and output. Wiring can reduce 1/10-1/100 of the mutual relay control system, and the faults caused by poor contact of contacts can be greatly reduced

PLC adopts a series of hardware and software anti-interference measures, which has strong anti-interference ability. The average time between failures reaches more than tens of thousands of hours. It can be directly used in industrial production sites with strong interference. PLC has been recognized as one of the most reliable industrial control equipment by the majority of users

4. The design, installation and debugging workload of the system is less

PLC replaces a large number of intermediate relays and time relays in the relay control system with software functions. 1 extensive plastic granulator is changed into combined, intelligent plastic granulator, counter and other devices, which greatly reduces the design, installation and wiring workload of the control cabinet

The ladder program of

PLC generally adopts the sequential control design method. This programming method is very regular and easy to master. For complex control system, the design time of ladder diagram is much less than that of relay system circuit diagram

the user program of PLC can be simulated and debugged in the laboratory, the input signal is simulated with a small switch, and the state of the output signal can be observed through the LED on PLC. After completing the installation and wiring of the system, the problems found in the process of on-site unified commissioning can generally be solved by modifying the program, and the commissioning time of the system is much less than that of the relay system

simple programming method

ladder diagram is the programming language of programmable controller with large load, fixture, strain measurement and safety performance. Its circuit symbols and expression are similar to the relay circuit schematic diagram. The ladder diagram language is intuitive and easy to learn and understand. Electrical technicians familiar with the relay circuit diagram can be familiar with the ladder diagram language in a few days, And used to compile user programs

ladder diagram language is actually a high-level language for users. When the programmable controller executes the ladder diagram program, it uses the interpreter to "translate" it into assembly language and then execute it

less maintenance workload, convenient maintenance, low failure rate, and perfect self diagnosis and display functions. Or when the external input device and actuator fail, the cause of the failure can be quickly found out according to the LED on the or the accommodation provided by the programmer, and the failure can be quickly eliminated by replacing the module

small volume and low energy consumption

for complex control systems, the use of PLC can reduce a large number of intermediate relays and time relays. The small volume is equivalent to the size of several relays. Therefore, the volume of the switch cabinet can be reduced to much less than that of the relay control system. Therefore, a large number of wiring and accessories can be saved, a large number of installation and wiring hours can be reduced, and a large amount of costs can be reduced. Learn hard and do well

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