Siemens SINUMERIK 840D sl Programming Manual page 19

2nd letter
N
C
A
Supplementary conditions
Exceptions in the prefix system
The following system of variables deviate from the prefix system specified above:
● $TC_...: Here, the 2nd letter C does not refer to channel-specific system variables but to
● $P_ ...: Channel-specific system variables
Use of machine and setting data in synchronized actions
When machine and setting data is 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:
ID=1 WHENEVER $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:
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:
Parameter Manual, System Variables
See also
Variables (Page 17)
Job Planning
Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
Meaning: Visibility
NCK-global variable (NCK)
Channel-specific variable (Channel)
Axis-specific variable (Axis)
toolholder-specific system variables (TC= tool carrier).
Flexible NC programming
1.1 Variables
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