TABLE OF CONTENTS Each line of in a CNC program is called a block. In the terminology established earlier, a block was defined as a single instruction processed by the CNC system.
A sequence block, a program block - or simply a block - is normally one hand written line in the program copy, or a line typed in a text editor and terminated by the Enter key. This line can contain one or more program words - words that result in the definition of a single instruction to the CNC machine. Such a program instruction may contain a combination of preparatory commands, coordinate words, tool functions and commands, coolant function, speeds and feeds commands, position registration, offsets of different kinds, etc. In plain English, the contents of one block will be processed as a single unit before the control processes any following block. When the whole CNC program is processed, the system will evaluate individual instructions (blocks) as one complete machine operation step. Each program consists of a series of blocks necessary to complete a certain machining process. The overall program length will always depend on the total number of blocks and their size.
As many program words as necessary are allowed in a single block. Some controls impose a limit on the number of characters in one block. There is only a theoretical maximum for Fanuc and similar controls, irrelevant in practice. The only restriction is that two or more duplicated words (functions or commands)...
