Functional features of PLC (2)

Functional features of PLC (2)

1. High reliability and strong anti-interference ability

Traditional relay control system uses a large number of intermediate relays and time relays, which are prone to failure due to poor contact. PLC uses software to replace a large number of intermediate relays and time relays, leaving only a small number of hardware components related to input and output. Wiring can be reduced to 1 / 10-1 / 100 of relay control system, and the failure caused by poor contact is greatly reduced.

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

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

PLC replaces a large number of intermediate relays, time relays, counters and other devices in the relay control system with software functions, which greatly reduces the workload of the design, installation and wiring of the control cabinet.

The ladder diagram program of PLC is generally designed by sequential control design method. This programming method is very regular and easy to master. For complex control system, the time of designing ladder diagram is much less than that of designing circuit diagram of relay system with the same function.

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 the PLC. After the installation and wiring of the system are completed, the problems found in the process of field unified debugging can be solved by modifying the program. The debugging time of the system is much less than that of the relay system.

3. The maintenance workload is small and the maintenance is convenient

The failure rate of PLC is very low, and it has perfect self diagnosis and display function. When PLC or external input device and actuator fail, the cause of the fault can be quickly found out according to the information provided by the light-emitting diode or programmer on PLC, and the fault can be quickly eliminated by replacing the module.