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Instruction List
Instruction list (IL) is one of the 5 languages supported by the initial versions of IEC 61131-3 standard, and subsequently deprecated in the third edition. It is designed for programmable logic controllers (PLCs). It is a low level language and resembles assembly. All of the languages share IEC61131 Common Elements. The variables and function call are defined by the common elements so different languages can be used in the same program. Program control (control flow) is achieved by ''jump'' instructions and function calls (subroutines with optional parameters). The file format has now been standardized to XML by PLCopen. Example Variations from IEC 61131 Many vendors whilst incorporating the full IEC 61131-3 requirements have additional vendor specific calls/function blocks to suit their hardware such as reading or writing to I/O. Siemens PLC instruction list language is known as "Statement List" or "STL" in English, and "Anweisungs-Liste" or "AWL" in German, Italian and S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEC 61131-3
IEC 61131-3 is the third part (of 10) of the open international standard IEC 61131 for programmable logic controllers. It was first published in December 1993 by the IEC; the current (third) edition was published in February 2013. Part 3 of ''IEC 61131'' deals with basic software architecture and programming languages of the control program within PLC. It defines three graphical and two textual programming language standards: * Ladder diagram (LD), graphical * Function block diagram (FBD), graphical * Structured text (ST), textual * Instruction list (IL), textual (deprecated in 3rd edition of the standard) * Sequential function chart (SFC), has elements to organize programs for sequential and parallel control processing, graphical. Data types * Elementary Data Type ** Bit Strings – groups of on/off values *** BOOL - 1 bit (0,1) *** BYTE – 8 bit (1 byte) *** WORD – 16 bit (2 byte) *** DWORD – 32 bit (4 byte) *** LWORD – 64 bit (8 byte) ** INTEGER – whole num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programmable Logic Controller
A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity that requires high reliability, ease of programming, and process fault diagnosis. Dick Morley is considered as the father of PLC as he had invented the first PLC, the Modicon 084, for General Motors in 1968. PLCs can range from small modular devices with tens of inputs and outputs (I/O), in a housing integral with the processor, to large rack-mounted modular devices with thousands of I/O, and which are often networked to other PLC and SCADA systems. They can be designed for many arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory. PLCs were first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-level Programming Language
A low-level programming language is a programming language that provides little or no Abstraction (computer science), abstraction from a computer's instruction set architecture—commands or functions in the language map that are structurally similar to processor's instructions. Generally, this refers to either machine code or assembly language. Because of the low (hence the word) abstraction between the language and machine language, low-level languages are sometimes described as being "close to the hardware". Programs written in low-level languages tend to be relatively Software portability, non-portable, due to being optimized for a certain type of system architecture. Low-level languages can convert to machine code without a compiler or Interpreter (computing), interpreter—second-generation programming languages use a simpler processor called an Assembly language#Assemble, assembler—and the resulting code runs directly on the processor. A program written in a low-level lan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assembly Language
In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported. The first assembly code in which a language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth's 1947 work, ''Coding for A.R.C.''. Assembly code is converted into executable machine code by a utility program referred to as an '' assembler''. The term "assembler" is generally attributed to Wilkes, Wheeler and Gill in their 1951 book '' The Preparation of Programs for an Electronic Di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEC61131 Common Elements
IEC 61131-3 is the third part (of 10) of the open international standard IEC 61131 for programmable logic controllers. It was first published in December 1993 by the IEC; the current (third) edition was published in February 2013. Part 3 of ''IEC 61131'' deals with basic software architecture and programming languages of the control program within PLC. It defines three graphical and two textual programming language standards: * Ladder diagram (LD), graphical * Function block diagram (FBD), graphical * Structured text (ST), textual * Instruction list (IL), textual (deprecated in 3rd edition of the standard) * Sequential function chart (SFC), has elements to organize programs for sequential and parallel control processing, graphical. Data types * Elementary Data Type ** Bit Strings – groups of on/off values *** BOOL - 1 bit (0,1) *** BYTE – 8 bit (1 byte) *** WORD – 16 bit (2 byte) *** DWORD – 32 bit (4 byte) *** LWORD – 64 bit (8 byte) ** INTEGER – whole num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Flow
In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''imperative programming'' language from a '' declarative programming'' language. Within an imperative programming language, a ''control flow statement'' is a statement that results in a choice being made as to which of two or more paths to follow. For non-strict functional languages, functions and language constructs exist to achieve the same result, but they are usually not termed control flow statements. A set of statements is in turn generally structured as a block, which in addition to grouping, also defines a lexical scope. Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchronous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jump (computer Science)
A branch is an instruction in a computer program that can cause a computer to begin executing a different instruction sequence and thus deviate from its default behavior of executing instructions in order. ''Branch'' (or ''branching'', ''branched'') may also refer to the act of switching execution to a different instruction sequence as a result of executing a branch instruction. Branch instructions are used to implement control flow in program loops and conditionals (i.e., executing a particular sequence of instructions only if certain conditions are satisfied). A branch instruction can be either an ''unconditional branch'', which always results in branching, or a ''conditional branch'', which may or may not cause branching depending on some condition. Also, depending on how it specifies the address of the new instruction sequence (the "target" address), a branch instruction is generally classified as ''direct'', ''indirect'' or ''relative'', meaning that the instruction contai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subroutines
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Functions may be defined within programs, or separately in libraries that can be used by many programs. In different programming languages, a function may be called a routine, subprogram, subroutine, method, or procedure. Technically, these terms all have different definitions, and the nomenclature varies from language to language. The generic umbrella term ''callable unit'' is sometimes used. A function is often coded so that it can be started several times and from several places during one execution of the program, including from other functions, and then branch back (''return'') to the next instruction after the ''call'', once the function's task is done. The idea of a subroutine was initially conceived by John Mauchly during his work on ENIAC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PLCopen
PLCopen is an independent organisation providing efficiency in industrial automation based on the needs of users. PLCopen members have concentrated on technical specifications around IEC 61131-3, creating specifications and implementations in order to reduce cost in industrial engineering. The outcome for example is standardized libraries for different application fields, harmonized language conformity levels and engineering interfaces for exchange. Experts of the PLCopen members are organized in technical committees and together with end users define such open standards. PLCopen was founded in 1992 just after the world wide programming standard IEC 61131-3 was published. The controls market at that time was a very heterogeneous market with different types of programming methods for many different PLCs. The IEC 61131-3 is a standard defining the programming languages for PLCs, embedded controls, and industrial PCs, harmonizing applications independent from specific dialects, but sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mnemonic
A mnemonic ( ) device, or memory device, is any learning technique that aids information retention or retrieval (remembering) in the human memory for better understanding. Mnemonics make use of elaborative encoding, retrieval cues, and imagery as specific tools to encode information in a way that allows for efficient storage and retrieval. Mnemonics aid original information in becoming associated with something more accessible or meaningful—which, in turn, provides better retention of the information. Commonly encountered mnemonics are often used for lists and in auditory form, such as short poems, acronyms, initialisms, or memorable phrases, but mnemonics can also be used for other types of information and in visual or kinesthetic forms. Their use is based on the observation that the human mind more easily remembers spatial, personal, surprising, physical, sexual, humorous, or otherwise "relatable" information, rather than more abstract or impersonal forms of informa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1-bit Architecture
In computer architecture, 1-bit integers or other data units are those that are (1/8 octet) wide. Also, 1-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers of that size. There are no computers or microcontrollers of any kind that are exclusively 1-bit for all registers and address buses. A 1-bit register can only store 21 different values, i.e. 0 or 1 (off or on, respectively). This is very restrictive and therefore not enough for a program counter which, on modern systems, is implemented in an on-chip register, that isn't implemented on-chip in some 1-bit systems. Opcodes for at least one 1-bit processor architecture were 4-bit and the address bus was 8-bit. While 1-bit CPUs are obsolete, the first carbon nanotube computer from 2013 is a 1-bit one-instruction set computer (and has only 178 transistors). 1-bit A serial computer processes data a single bit at a time. For example, the PDP-8/S was a 12-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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