工科畢業(yè)設(shè)計(jì)英文翻譯-plc-文庫(kù)吧資料
2024-12-02 02:08本頁(yè)面
【正文】 s PLCs can municate over a wide range of media including RS485, Coaxial, and even Ether for I/O control at work speeds up to 100 Mbit/s. Programming Early PLCs, up to the mid1980s, were programmed using proprietary programming panels or specialpurpose programming terminals. they were designed to replace relay logic systems. These PLCs were programmed in ladder logic, which strongly resembles a schematic diagram of relay logic. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a Very High Level Programming Language designed to program PLCs based on State Transition Diagrams. Recently, the International standard IEC 611313 has bee popular. IEC 611313 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical anization of operations. While the fundamental concepts of PLC programming are mon to all manufacturers, differences in I/O addressing, memory anization and instruction sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly patible. User interface PLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control. A HumanMachine Interface (HMI) is employed for this purpose. HMI39。flutter39。 for example, aircraft flight controls. PLCs may include logic for singlevariable feedback analog control loop, a proportional, integral, derivative or PID controller. A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops。 For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities. A microcontrollerbased design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and input/output hardware) can be spread over many sales, and where the enduser would not need to alter the control. Automotive applications are an example。Programmable logic controller Cynthia Cooper From Wikipedia, the free encyclopedia A programmable logic controller or simply programmable controller is a digital puter used for automation of industrial processes, such as control of machinery on factory assembly lines. Unlike generalpurpose puters, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in batterybacked or nonvolatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result. Features Control panel with PLC (grey elements in the center). The u
公司管理相關(guān)推薦
鄂ICP備17016276號(hào)-1