Method and apparatus for symbolic ladder logic programming with automatic attachment of addresses

Abstract

The present invention discloses a method of identifying elements in a plurality of data table files of a programmable logic controller using symbols to represent the addresses thereof. This, and other techniques, provide means for managing and economizing the allocation of memory. The software package tracks which of the elements are represented by symbols and which of the elements are available. Symbols can be attached to element addresses by the user displaying a list of previously defined symbols and selecting a symbol from the list. Symbols can be attached to element addresses by the user selecting a particular Data Table file and simply requesting the next available element address from the file. Symbols can also be automatically attached to elements in new Data Table files. The user specifies the file type for the new Data Table file and the software package creates the new file. At the same time, the software package will automatically attach the symbol to the address of the first element in the new created file. The user has the option of manually attaching symbols to elements in the Data Table files. The user selects a Data Table file and the software package displays the contents of the file on the screen. The user positions the cursor on the desired element and the software package attaches the symbol to the address of the element.

Dependencies are inferred from the claim text.