Block Rules - Siemens SINUMERIK 840D sl Programming Manual

Effectiveness of commands
Commands are either modal or non-modal:
• Modal
Modal commands retain their validity with the programmed value (in all following blocks)
until:
-
-
• Non-modal
Non-modal commands only apply for the block in which they were programmed.
End of program
The last block in the execution sequence contains a special word for the end of program: M2,
M17 or M30.
2.2.2

Block rules

Start of block
NC blocks can be identified at the start of the block by block numbers. These consist of the
character "N" and a positive integer, e.g.
N40 ...
The order of the block numbers is arbitrary, however, block numbers in rising order are
recommended.
Note
Block numbers must be unique within a program in order to achieve an unambiguous result
when searching.
End of block
A block ends with the character LF (LINE FEED = new line).
Note
The LF character does not have to be written. It is generated automatically by the line
change.
Fundamentals
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
A new value is programmed under the same command
A command is programmed that revokes the effect of the previously valid command
Fundamental Principles of NC Programming
2.2 Structure and contents of an NC program
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