Link Variables; Link Axes - Siemens SINUMERIK Series Function Manual

2.1.2.2

Link variables

Link variables are global system user variables that for configured link communication can
be used by all NCUs of the network. Link variables can read and written in part programs,
cycles and synchronized actions.
The reading and writing of link variables is performed in the main run. A channel
synchronization is therefore performed implicitly with regard to the link variables so that all
channels read the same value in the same interpolator cycle. By comparison, global user
data (GUD) can also be used cross-channel like the link variables. However, as the GUD is
processed in the preprocessing, no implicit channel synchronization is performed here. If
necessary, GUD must therefore be synchronized by the user through specific programming.
Note
On systems without an NCU link, link variables can also be used as additional global user
data alongside standard global user data (GUD).
2.1.2.3

Link axes

Link axes enable the creation of distributed control systems, in which the setpoints of the
machine axes are not created by channels of the NCU to which the machine axes are
physically connected, but by channels of an arbitrary NCU of the link group.
Fixed assignment for link axes
The assignment, on which NCU the setpoints for which machine axis are created, is fixed for
link axes through the machine data configuration.
Variable assignment for container link axes
The assignment is variable for container link axes. A container link axis can therefore be
traversed alternatively by each NCU of the link group. See Section "Axis container
(Page 100)".
Irrespective of the assignment described above, the logical machine axis can be made
known to the link axis of several channels on the NCU generating the setpoint and then
functionally handled as a local logical machine axis, e.g. master value for position/feed
couplings, NCU-local axis interchange.
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
B3: Distributed systems - 840D sl only
2.1 Brief description
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