Link Variables - Siemens SINUMERIK 840D sl Function Manual

MD18780 $MN_ MM_NCU_LINK_MASK, Bit 0 = 1
Note
Activation time
It is recommended to activate the link communication only after complete commissioning of
the entire functionality on all participating NCUs has been done.
3.2.2

Link variables

Complex systems with several NCUs require for the complete system coordination of the
manufacturing processes a cyclic exchange of user-specific data between the NCUs. The data
exchange is performed via the link communication and a special memory area, the link
variables memory available for each NCU.
The size and data structure of the link variables memory can be specified for each specific
user. The data stored in the link variables memory is addressed using a special $A_DLx link
variable.
These are system-global user variables that can be read and written in part programs and
cycles by all NCUs involved in a link group if link communication has been configured. Unlike
global user variables (GUD), link variables can also be used in synchronized actions.
Figure 3-7
Requirement
The use of link axes requires a link communication defined in accordance with "Section Link
communication (Page 83)".
Link variable as NCU-global user variable
Note
If an NCU Is not a node of a link group or the link variables are not required for communication
via NCU link, the link variables can be used as the NCU-global user variables.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Link variables
B3: Distributed systems - 840D sl only
3.2 NCU link
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