【正文】 N = Network 21 // 轎廂上行記憶信號(hào)LD O AN AN = Network 22 // 轎廂在四樓時(shí)下行信號(hào)LD O O O O O AN AN AN = Network 23 // 轎廂在三樓時(shí)下行信號(hào)LD O O O O A = Network 24 // 轎廂在二樓時(shí)下行信號(hào)LD O A = Network 25 // 轎廂下行信號(hào)LD O O = Network 26 // 轎廂下行LD ON A AN AN AN AN = Network 27 // 轎廂下行記憶信號(hào)LD O AN AN = Network 28 // 轎廂外呼信號(hào)保持LD O AN = Network 29 LD AN O AN = Network 30 LD AN O AN = Network 31 LD AN O AN = Network 32 LD AN O AN = Network 33 LD O AN = Network 34 // 轎廂內(nèi)呼保持LD O AN = Network 35 LD O A = Network 36 LD O AN = Network 37 LD O AN = Network 38 // 各樓層停車信號(hào)LD O AN A = Network 39 LD O O AN A = Network 40 LD O O AN A = Network 41 LD O AN A = Network 42 // 手動(dòng)及自動(dòng)開門LD O O T37O AN AN AN = Network 43 LD O O O LPSAN TON T37, 20LPP= Network 44 // 手動(dòng)及自動(dòng)關(guān)門LD O O T38AN AN = Network 45 LD TON T38, 50Network 46 LD O AN = Network 47 // 保持信號(hào)的取消LD = Network 48 // 電梯外呼信號(hào)的開門信號(hào)LD A LD O A OLDLD O A OLDLD A OLD=
附錄2 英語(yǔ)原文Programmable Logic Controllers (PLCS) 1 About Programmable Logic Controllers (PLCs) PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard puter interfaces and proprietary languages and network options. Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels. Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible bination of these values. Expandable units may be stacked or linked together to increase total control capacity. Maximum number of channels refers to the maximum total number of input and output channels in an expanded system. PLC system specifications to consider include scan time, number of instructions, data memory, and program memory. Scan time is the time required by the PLC to check the states of its inputs and outputs. Instructions are standard operations (such as math functions) available to PLC software. Data memory is the capacity for data storage. Program memory is the capacity for control software. Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs. Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac. Programming options for PLCs include front panel, hand held, and puter. Programmable logic controllers use a variety of software programming languages for control. These include IEC 611313, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic. The IEC 611313 programming environment provides support for five languages specified by the global standard: Sequential Function Chart, Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multivendor patibility and multilanguage programming. SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences. FBD uses a broad function library to build plex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable munication and interface functions. LD is a graphic language for discrete control and interlocking logic. It is pletely patible with FBD for discrete function control. ST is a text language used for plex mathematical procedures and calculations less well suited to graphical languages. IL is a lowlevel language similar to assembly code. It is used in relatively simple logic instructions. Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic. Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries. C is a high level programming language suited to handle the most plex putation, sequential, and data logging tasks. It is typically developed and debugged on a PC. BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions. Programmable logic controllers can also be specified with a number of puter interface options, network specifications and features. PLC power options, mounting options and environmental operating conditions are all also important to consider.2 INTRODUCTIONFor simple programming the relay model of the PLC is sufficient. As more plex functions are used the more plex VonNeuman model of the PLC must be