LWN2660-6EG 3BHL000986P7002 ABB power supply external internal industry
Before the 1960s, the automatic control system of the automobile production line was basically composed of the relay control device. At that time, every modification of the automobile directly led to the redesign and installation of the relay control device. With the development of production, the new cycle of the automobile model is getting shorter and shorter. In order to change this situation, the United States General Motors Company in 1969 public bidding, requiring the replacement of the relay control device with a new control device, and put forward ten bidding indicators, namely:
Most of these have remained the basic definition of a PLC until now (except for the seventh input which can be AC 115V, which has now been replaced by DC24V).
In 1969, the United States Digital Equipment company (DEC) developed PLC, in the United States General Motors automatic assembly line, achieved success, this first industrial control device with its simple and easy to understand, easy to operate, high reliability, general flexibility, small size, long service life and a series of advantages, quickly in the United States to promote the application of other industrial fields. By 1971, it had been successfully applied to food, beverage, paper and other industries.
The emergence of this first industrial control device has also been highly valued by other countries in the world. 1971 from the United States introduced this new technology, quickly developed a PLC, in 1973, Western European countries also developed their PLC. China began to introduce and develop from 1974, but has not been very successful, for many reasons, until 2004, the whole PLC market is still dominated by imported brands.
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