B3: Distributed systems - 840D sl only
2.1 Brief description
Extended Functions
76 Function Manual, 03/2013, 6FC5397-1BP40-3BA1
2.1.2.4 Lead link axes
If in conjunction with the coupling functions of the generic coupling, all interpolators, i.e. the
setpoint-creating/processing channels, the leading and following axes/spindles, are on the
same NCU, the use of a lead link axis is not required. The machine axes of the leading
and/or following axes/spindles can also be connected link axes to different NCUs.
Application
A lead link axis is always required when not all interpolators of a coupling group are on the
same NCU. The lead link axis provides an image of the leading axis/spindle or the master
value for the local interpolators, on another NCU. Starting from this master value, the
setpoints of the following axes/spindles are then generated by the interpolators on this NCU.
Further application
A lead link axis is also used if more machine axes are involved in a coupling than are
available absolutely or relatively on an NCU for the coupling.
References
Special Functions Function Manual, Section "Axis couplings (M3)" > "Generic coupling"
2.1.2.5 Dependencies
In order that several axes can be traversed in an interpolatary relationship, it is essential that
the setpoints generated by the interpolator of the traversing channel be transferred to the
position control at the same time.
During the transfer of the setpoints via the NCU link, for example, for a link axis there is a
delay of one interpolator cycle in relation to the setpoint of a local axis. The delay must be
compensated by a suitable increase of the buffer between the interpolator and the position
controller :
MD18720 $MN_MM_SERVO_FIFO_SIZE = <value> = <default value + compensation value>
Function Compensation value
Link axis
Container-link axis
One interpolator cycle must be compensated on all NCUs with axes that
interpolate with a link or container link axis.
Compensation value = 1
Lead-link axis Two interpolator cycles must be compensated on the NCU of the leading
axis that generates the setpoints for the lead link axis.
Compensation value = 2
Note
In contrast to lead link axes, link and container link axes require another compensation value
(MD18720 $MN_MM_SERVO_FIFO_SIZE). With simultaneous use of link or container link
axes and lead link axes within a link group, the delays cannot be compensated.
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