PLC Programmable Logic Controller in Passenger Elevator
PLC Programmable logic controller (PLC) is a new type of industrial control device based on computer technology that can be used for passenger elevators. PLC is a kind of electronic device specially designed for digital operation applied in industrial environment. It uses programmable memory to store instructions for operations such as logic operations, sequential operations, clocking, counting, and arithmetic operations in its own interior and to control various types of inputs and outputs through digital or analog inputs Mechanical or production process. PLCs and their associated peripherals should be designed to be easily integrated into an industrial control system and easy to extend their functionality.
High reliability is the key performance of electrical control equipment. PLC due to the use of modern large-scale integrated circuit technology, the use of strict manufacturing process, the internal circuit to take advanced anti-jamming technology, with high reliability. For example, Mitsubishi F series PLC produced an average time to failure of up to 300,000 hours. Some PLCs with redundant CPUs have an even longer MTBF. PLC from the machine outside the circuit, the use of PLC control system constitutes, and the same size compared to the relay contactors, electrical wiring and switch contacts have been reduced to hundreds or even a few thousandths, the fault will be greatly reduced. In addition, PLC with hardware fault self-detection function, in the event of failure can be timely warning message. When used in passenger elevators, in application software, the user can also program fault self-diagnosis programs of peripheral devices to make the system self-diagnosis and protection of circuits and devices other than PLC. In this way, it is no surprise that the entire system is extremely reliable.
PLC development today, has formed a large, medium and small series of various products of the scale. Can be used for passenger elevator control of all sizes. In addition to logic processing functions, most of modern PLC has a complete data computing capabilities, can be used for a variety of digital control. In recent years, a large number of PLC functional units emerge, so that PLC penetration into the position control, temperature control, CNC and other industrial control. Coupled with the enhanced PLC communication capabilities and the development of man-machine interface technology, the use of PLC to form a variety of control systems has become very easy.