Siemens SINUMERIK 840DE Programming Manual page 52

Fundamental Principles of NC Programming
2.2 Language elements of the programming language
Main block/subblock
There are two types of blocks:
• Main blocks and
• subblocks
The main block must contain all the words necessary to start the operation sequence in the
program section beginning with the main block.
Note
Main blocks can be contained in both main programs and subprograms. The control does
not check whether a main block contains all the necessary information.
Block number
Main blocks are identified by a main block number. A main block number comprises the
character ":" and a positive whole number (block number). The block number always
appears at the start of a block.
Note
Main block numbers must be unique within a program to achieve an unambiguous result
when searching.
Example:
:10 D2 F200 S900 M3
Subblocks are identified by a subblock number. A subblock number comprises the character
"N" and a positive whole number (block number). The block number always appears at the
start of a block.
Example:
N20 G1 X14 Y35
N30 X20 Y40
Note
Subblock numbers must be unique within a program in order to achieve an unambiguous
result when searching.
The order of the block numbers is arbitrary, however increasing block numbers are
recommended. You can also program NC blocks without block numbers.
2-6
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals