Siemens SINUMERIK 840D sl Programming Manual page 18

Flexible NC programming
1.1 Variables
2nd letter
N
C
A
General conditions
Exceptions to the rules of the prefix system
The following system variables deviate from the rules of the prefix system described above:
● $TC_...: Here, the second letter C does not refer to channel-specific system variables but
● $P_ ...: Channel-specific system variables
Use of machine and setting data in synchronized actions
When machine and setting data are used in synchronized actions, the prefix can be used to
define whether the machine or setting data will be read synchronous to the preprocessing
run or the main run.
If the data remains unchanged during machining, it can be read synchronous to the
preprocessing run. For this purpose, the machine or setting data prefix is written with a $
sign:
Program code
ID=1 WHENEVER G710 $AA_IM[z] < $SA_OSCILL_REVERSE_POS2[Z]–6 DO $AA_OVR[X]=0
If the data changes during machining, it must be read/written synchronous to the main run.
For this purpose, the machine or setting data prefix is written with two $ signs:
Program code
ID=1 WHENEVER $AA_IM[z] < $$SA_OSCILL_REVERSE_POS2[Z]–6 DO $AA_OVR[X]=0
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Significance: Visibility
NCK-global variable (NCK)
Channel-specific variable (Channel)
Axis-specific variable (Axis)
to toolholder-specific system variables (TC= tool carrier).
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
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