Siemens SINUMERIK 840Di Function Manual page 782

Detailed Description
2.4 Frames
2.4.4.3 NCU global frames
All settable frames G54 to G599 and all basic frames can be configured NCU globally or
channel-specifically. A combination of these is also possible with basic frames. Global
frames affect all channels on an NCU. All channels have read and write access to the NCU.
Global frames only have axial frame components, such as translations, scales and mirrors of
individual axes. Each channel can read or modify global frames for any machine axis.
A characteristic of global frames is that they are calculated in all channels of an NCU. As the
assignment of machine axes to channel axes and, in particular, to geometry axes, can be
different in all channels, there is no geometric relationship. Global frames describe offsets,
scales and mirrors of machine axes. Rotations cannot be used on global frames.
All settable frames can be reconfigured as global frames via machine data
MD18601 $MN_MM_NUM_GLOBAL_USER_FRAMES.
If the value of this machine data is greater than zero, there are no channel-specific settable
frames.
Machine data
MD28080 $MC_MM_NUM_USER_FRAMES
is then irrelevant and is not evaluated.
The number of global basic frames is configured via machine data
MD18602 $MN_MM_NUM_GLOBAL_BASE_FRAMES.
The machine data
MD28081 $MC_MM_NUM_BASE_FRAMES
can also make channel-specific basic frames available simultaneously.
Global frames can be read and written from all channels of an NCU. When writing global
frames, the user must ensure channel coordination. This can be achieved using wait
markers, for example.
2.4.5 Frame chain and coordinate systems
2.4.5.1 Overview
The figure below shows the frame chain for the current complete frame. The frame chain is
stored between the BCS and WCS. The SZS (Settable Zero System) corresponds to the
WCS, transformed by the programmable frame. The BZS (Basic Zero System) still includes
the current settable frame. The system frame for the zero offset external is only available if it
has been configured, otherwise the zero offset external is interpolated as a superimposed
motion of the axis, as it has been up to this point.
2-52
Axis Types, Coordinate Systems, Frames (K2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0