Siemens SINUMERIK 840D sl Programming Manual page 378

Fundamentals
2.15 Other information
Further information
Requirements
● The NCUs involved, i.e., NCU1 to NCU<n> (<n> equals max. of 8), must be interconnected
via the link module for high-speed communication.
Reference:
Device Manual Configuration NCU
● The axis must be configured appropriately by machine data.
● The "Link axis" option must be installed.
● The same interpolator clock cycle must be configured for all participating NCUs.
Restrictions
● A master axis, which is a leading link axis, cannot be a link axis, i.e. it cannot be traversed
by NCUs other than its home NCU.
● A master axis, which is a leading link axis cannot be a container axis, i.e. it cannot be
addressed alternately by different NCUs.
● A leading link axis cannot be the programmed as leading axis in a gantry grouping.
● Couplings with leading link axes cannot be cascaded.
● Axis replacement can only be implemented within the home NCU of the leading link axis.
System variables
The following system variables can be used in conjunction with the channel axis identifier of the
leading link axis:
System variable
$AA_LEAD_SP
$AA_LEAD_SV
If these system variables are updated by the home NCU of the master axis, the new values are
also transferred to any other NCUs that wish to control slave axes as a function of this master
axis.
378
Meaning
Simulated master value - position
Simulated master value - velocity
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming