關(guān)于plc的畢業(yè)設(shè)計(jì)外文及翻譯-plc設(shè)計(jì)-展示頁(yè)
2025-05-27 16:02本頁(yè)面
【正文】 previously found only in larger PLCs. This has made specifying a larger PLC just for additional features or performance, and not increased I/O count, unnecessary, as even those in the nano class are capable of Ether munication, motion control, onboard PID with autotune, remote connectivity and more. PLCs are also now wellequipped to replace standalone process controllers in many applications, due to their ability to perform functions of motion control, data acquisition, RTU (remote telemetry unit) and even some integrated HMI (human machine interface) functions. Previously, these functions often required their own purposebuilt controllers and software, plus a separate PLC for the discrete control and interlocking. The Great Communicator Possibly the most significant change in recent years lies in the munications arena. In the 1970s Modicon introduction of Modbus munications protocol allowed PLCs to municate over standard cabling. This translates to an ability to place PLCs in closer proximity to real world devices and municate back to other system controls in a main panel. In the past 30 years we have seen literally hundreds of proprietary and standard protocols developed, each with their own unique 39。PLCs Past, Present and Future Everyone knows there39。s only one constant in the technology world, and that39。s PLCs have to be data pilers and information gateways. They have to interface with bar code scanners and printers, as well as temperature and analog sensors. They need multiple protocol support to be able to connect with other devices in the process. And furthermore, they need all these capabilities while remaining costeffective and simple to program. Another primary development that has literally revolutionized the way PLCs are programmed, municate with each other and interface with PCs for HMI, SCADA or DCS applications, came from the puting world. Use of Ether munications on the plant floor has doubled in the past five years. While serial munications remain popular and reliable, Ether is fast being the munications media of choice with advantages that simply can39。s performed so well for so long. Hardware Platforms The modern PLC has incorporated many types of Commercial off the Shelf (COTS) technology in its CPU. This latest technology gives the PLC a faster, more powerful processor with more memory at less cost. These advances have also allowed the PLC to expand its portfolio and take on new tasks like munications, data manipulation and highspeed motion without giving up the rugged and reliable performance expected from industrial control equipment. New technology has
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