Flexible Nc Programming - Siemens SINUMERIK 840D sl Programming Manual

Flexible NC programming

1.1 Variables
Preprocessing variables
Preprocessing variables are system variables that are read and written in the context of
preprocessing; in other words, at the point in time at which the part program block in which
the system variable is programmed is interpreted. Preprocessing variables do not trigger
preprocessing stops.
Main run variables
Main run variables are system variables which are read and written in the context of the main
run; in other words at the point in time at which the part program block in which the system
variable is programmed is executed. The following are main run variables:
● System variables which can be programmed in synchronized actions (read/write)
● System variables which can be programmed in the part program and trigger
● System variables which can be programmed in the part program and whose value is
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
Whether machine and setting data is treated as preprocessing or main run variables depends on
1)
whether they are written with one or two $ characters. The notation is freely selectable for the specific
application.
When an R-parameter is used in the part program/cycle as a preprocessing variable, the prefix is
2)
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.
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preprocessing stops (read/write)
calculated during preprocessing but not written until the main run (main run synchronized:
write only)
Meaning: Data type
Machine data
Setting data, protection zones
Tool management data
Programmed values
Cycle variables of ISO envelope cycles
Option data
R-parameters (arithmetic parameters)
Machine data
Setting data
Current main run data
Servo data
R-parameters (arithmetic parameters)
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Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
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