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G-code (also ''RS-274''), which has many variants, is the common name for the most widely used numerical control (NC) programming language. It is used mainly in computer-aided manufacturing to control automated machine tools. G-code is sometimes called G programming language, not to be confused with LabVIEW's G programming language. G-code is a language in which people tell computerized machine tools how to make something. The "how" is defined by instructions on where to move, how fast to move, and what path to move. The most common situation is that, within a machine tool, a cutting tool is moved according to these instructions through a toolpath and cuts away material to leave only the finished workpiece. The same concept also extends to noncutting tools such as forming or burnishing tools, photoplotting, additive methods such as 3D printing, and measuring instruments. ==Implementations== The first implementation of a numerical control programming language was developed at the MIT Servomechanisms Laboratory in the late 1950s. In the decades since, many implementations have been developed by many (commercial and noncommercial) organizations. G-code has often been used in these implementations. The main standardized version used in the United States was settled by the Electronic Industries Alliance in the early 1960s. A final revision was approved in February 1980 as ''RS-274-D''. In other countries, the standard ''ISO 6983'' is often used, but many European states use other standards. For example, ''DIN 66025'' is used in Germany, and PN-73M-55256 and PN-93/M-55251 are used in Poland. Extensions and variations have been added independently by control manufacturers and machine tool manufacturers, and operators of a specific controller must be aware of differences of each manufacturer's product. One standardized version of G-code, known as ''BCL'', is used only on very few machines. During the 1970s through 1990s, many CNC machine tool builders attempted to overcome compatibility difficulties by standardizing on machine tool controllers built by Fanuc. Siemens was another market dominator in CNC controls, especially in Europe. In the 2010s, controller differences and incompatibility are not as troublesome because machining operations are developed with CAD/CAM applications that can output the appropriate G-code for a specific machine tool. Some CNC machines use "conversational" programming, which is a wizard-like programming mode that either hides G-code or completely bypasses the use of G-code. Some popular examples are Southwestern Industries' ProtoTRAK, Mazak's Mazatrol, Hurco's Ultimax, Haas' Intuitive Programming System (IPS), and Mori Seiki's CAPS conversational software. G-code began as a limited type of language that lacked constructs such as loops, conditional operators, and programmer-declared variables with natural-word-including names (or the expressions in which to use them). It was unable to encode logic; it was just a way to "connect the dots" where many of the dots' locations were figured out longhand by the programmer. The latest implementations of G-code include such constructs, creating a language somewhat closer to a high-level programming language. Additionally, all primary manufacturers (e.g. Fanuc, Siemens, Heidenhain) provide access to PLC data, such as axis positioning data and tool data,〔(【引用サイトリンク】title=Fanuc macro system variables )〕 via variables which can be used by NC programs. These constructs make it easier to develop automation applications. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「G-code」の詳細全文を読む スポンサード リンク
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