plc機(jī)械手控制系統(tǒng)文獻(xiàn)綜述(包括外文翻譯)-機(jī)械手-全文預(yù)覽
【正文】 PLC system all that is needed is a possibly vague idea of the size of the machine and the I/O requirements (how many inputs and outputs). The input and output cards are cheap at this stage, so a healthy spare capacity can be built in to allow for the inevitable omissions and future developments. Next es construction. With conventional schemes, every job is a ‘oneoff’ with inevitable delays and costs. A PLC system is simply bolted together fro m standard parts. During this time the writing of the PLC program is started (or at least the detailed program specification is written). The next stage is installation, a tedious and expensive business as sensors, actuators, limit switches and operator controls are cabled. A distributed PLC system using serial links and prebuilt and tested desks can simplify installation and bring huge cost benefits. The majority of the PLC program is written at this stage. Finally es missioning, and this is where the real advantages are found. No plant ever works first time. Human nature being what it is, there will be some oversights. Changes to conventional systems are time consuming and expensive. Provided the designer of the PLC system has built in spare memory capacity, spare I/O an
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