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Program Structure
A program can be classified as a "main program" or a "subprogram."
Main Program
Ordinarily, the machine operates according to instructions from a main program. A subprogram, which is described next, is basically
specified within a main program.
Subprogram
If a main program can be likened to the trunk of a tree, then subprograms are branches. When a main program specifies execution of a
subprogram of a certain number, the subprogram of that number is called up and executed.
Subprograms can be convenient when writing a program where the same task is to be performed a number of times. Program modular-
ity can also be promoted by creating subprograms which have good general utility.
A subprogram can call another subprogram.
Main
program
(Program No. 1)
N100M98P0002
N101G00X10.
..........
N176M98P0004
N177G00Y2.
Program Structure and Format
Programming proceeds in accordance with the process sheet that has been prepared. The program is input using a dedicated input
device for NC codes, or with a general-purpose computer.
Input is made as shown in the figure below. Addresses such as G, M, X, I, and J are combined with numbers to specify the cutting steps
and tool movements.
Data start
Sequence No.
* "%" for ISO or ASCII,
" ER " for EIA
(* For details on blocks, see "About Blocks," which is the following section.)
4
O0002
Subprogram
Call
(Program No. 2)
N254M98P0003
N255G00Y5.
M99
O0004
Call
Subprogram
(Program No. 4)
M99
Conceptual view of a main program and subprograms
Program No.
Preparatory function
Coordinate values, etc.
Address Value
Program end
O0003
Call
Subprogram
(Program No. 3)
M99
Feed rate
Words which express dimensions,
angles, and so on are called
"dimension words." Addresses for
dimension words include X, Y, Z, I,
J, K, and R.
Word
Spindle speed
Miscellaneous function
Block end
(start of the next block)
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