Siemens SINUMERIK 828D Programming Manual page 17

Prefix system
In order that they can be specifically identified, the names of system variables are usually
preceded by a prefix comprising the $ sign followed by one or two letters and an underscore.
$ + 1st letter
System variables which are read/written during preprocessing
$M
$S
$T
$P
$C
$O
R
System variables which are read/written during the main run
$$M
$$S
$A
$V
$R
1) When machine and setting data are used in the part program/cycle as preprocessing variables, the
prefix is written with one $ sign. When they are used in synchronized actions as main run variables,
the prefix is written with 2 $ characters.
2) When an R-parameter is used in the part program/cycle as a preprocessing variable the prefix is
omitted, e.g. R10. When it is used in a synchronized action as a main run variable, a $ sign is written
as a prefix, e.g. $R10.
2nd letter
N
C
A
Job planning
Programming Manual, 07/2010, 6FC5398-2BP40-0BA0
Significance: Data type
Machine data
1)
Setting data, protection zones
Tool management data
Programmed values
Cycle variables of ISO envelope cycles
Option data
R-parameters (arithmetic parameters)
Machine data
1)
Setting data
1)
Up-to-date main run data
Servo data
R-parameters (arithmetic parameters)
Significance: Visibility
NCK-global variable (NCK)
Channel-specific variable (Channel)
Axis-specific variable (Axis)
Flexible NC programming
1)
2)
2)
1.1 Variables
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