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1. Programmable Controller in Control
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PLC (Programmable Logic Controller) referred to as PLC or PC, is from the early
development of relay logic control system from its absorption of micro-computer
technology to make it function grown gradually for complex control tasks.
PLC is full of vitality, that it is more suitable for industrial field and market
requirements: high reliability, strong anti-interference ability of all, easy to use
program to install, low price of long life. Than the SCM, its input and output closer to
the field devices, without adding too much in the middle of the interface components
or need more, so that saves users time and cost. PLC's bottom (input) for
the relay, transistor and thyristor control unit, while the top is generally user-oriented
micro-computer. People use it, you can not have specialized training in computer, can
operate on the PLC and programming. Used to perform a wide range of complexity of
different industrial control tasks.
Since the 1836 relay came, people began to lead it skillfully with the switching device
to connect, use different form of logic control or sequence control. So far, the PLC
programming languages - ladder can be seen in the shadow of these cabling. Until the
late 60s, early 70s came PLC, as microelectronics, computer technology and the rapid
development of data communication technologies, as well as the emergence of the
microprocessor, PLC

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