Siemens SINUMERIK 840D sl Programming Manual page 376

Fundamentals
2.15 Other information
Further information
Requirements
● The participating NCUs, NCU1 and NCU2, must be connected by means of high-speed
communication via the link module.
● The axis must be configured appropriately by machine data.
● The "Link axis" option must be installed.
Description
The position control is implemented on the NCU on which the axis is physically connected to
the drive. This NCU also contains the associated axis VDI interface. The position setpoints for
link axes are generated on another NCU and communicated via the NCU link.
The link communication must ensure the interaction between the interpolators and the position
controller or PLC interface. The setpoints calculated by the interpolators must be transported
to the position control loop on the home NCU and, vice versa, the actual values must be
returned from there back to the interpolators.
Axis container
An axis container is a circular buffer data structure, in which local axes and/or link axes are
assigned to channels. The entries in the circular buffer can be shifted cyclically.
In addition to the direct reference to local axes or link axes, the link axis configuration in the
logical machine axis image also permits references to axis containers. This type of reference
comprises:
● A container number and
● A slot (circular buffer location within the container)
The entry in a circular buffer location contains:
● A local axis or
● A link axis
Axis container entries contain local machine axes or link axes from the perspective of an
individual NCU. The entries in the logical machine axis image
(MD10002 $MN_AXCONF_LOGIC_MACHAX_TAB) of an individual NCU are fixed.
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Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming