Siemens Sinumerik 840D sl Programming Manual page 20

Flexible NC programming
1.1 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/written 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
Note
Writing machine data
When writing an item of machine or setting data, it is important to ensure that the access
level which is active when the part program/cycle is executed permits write access and that
the data is set to take "IMMEDIATE" effect.
References
A list of the properties of all system variables appears in:
List Manual, system variable
See also
General information about variables General information about variables [Page 17]
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Programming Manual, 02/2011, 6FC5398-2BP40-1BA0
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