外文翻譯--可編程控制器-其他專業(yè)-在線瀏覽
2025-03-24 10:01本頁(yè)面
【正文】 erefore, the vendors producing IECpliant PLCs that use the term configuration in the historic sense refer to the entire body of software with some other term, such as projects. A resource provides the support functions for the execution of programs. One or more resources constitute a configuration. Normally, a resource exists within a PLC, but it may exist within a personal puter to support program testing. One of the main functions of a resource is to provide an interface between a program and the physical I/O of the PLC. A program generally consists of an interconnection of function blocks, each of which may be written in any of the IEC languages. A function block or program is also called a program anization unit. In addition to the function blocks, the program contains declarations of physical inputs/outputs and any variables local to the program. A program can read and write to I/O channels, global variables, and municate with other programs. Provide the means to transfer information between con?gurations. Tasks control the execution of the program or parts of a program. A task controls one or more programs and/or function blocks to execute. The execution of a program implies that all of the function blocks in the program are processed once. The execution of a function block implies that all of the software elements of the function block are processed once. There are no implied mechanisms for program execution. In order for a program to be executed, it must be assigned to a task, and the task must be con?gured to execute continuously, p
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