Siemens Sinumerik 840D Operating Turning page 39

Layout of a CNC-program
A CNC-program, also known as part program, consists of a logical se-
quence of commands, which are executed step-by-step by the control unit
after the program has been started.
The manufacturers of control units recognize and apply the guidelines as
per DIN 66025.
Each program is compiled and stored under a program name in the con-
trol unit. The name can contain letters as well as numbers.
A block starts with a block number followed by the commands.
Each command consists of command words, which in turn consist of an
address letter (A-Z) and an associated numerical value (both upper or
lower case characters are permissible).
Program layout:
Departure information
Block
Auxil-
Nr..
iary
Coordinate axes
com-
mand
N G X Y
Geometrical data
The block number is a
ated by the control unit as a command. It is usually programmed to go up
in steps of 10 and serves only the user for better oversight. It has no effect
on the program execution.
The geometrical data include all instructions that clearly define mathemati-
cally the motion of the tool or the axes.
The technological data
and to pre-select the necessary cutting parameters feed rate and spindle
speed. Miscellaneous functions can control such things as direction of ro-
tation and auxiliary appliances.
Programming example:
....
N80 T1; Roughing tool
N90 M6
N100 G54 F0.2 S180 M4
N110 G00 X20 Y0 Z2 D1
N120
In order to improve the overview within a program, comments can be op-
tionally added at the end of a block. These must be preceded by a semi-
colon. Any characters that follow thereafter will not be taken into account
by the control unit.
840D/828D SINUMERIK Operate
Interpolation para-
meter
Z I J K
program-technical assignment, which is not evalu-
are used for instance to activate the required tool
Switching information
Feed Speed Tool
F S T
Technological data
Page 3
Section 2
Notes
Misc.
func-
tion
M
B501
B501