Siemens SINUMERIK 840D sl Function Manual page 850

Detailed description
2.4 Frames
2.4.4.2 Configurable SZS
The function of the SZS coordinate system is to display actual values and move the axes
during a cycle interruption. Cycles utilize frames in the frame chain to perform their functions.
They input translations or rotations into either the programmable frame or the cycle system
frame. The WCS is, therefore, modified by cycles. A user who uses Stop to interrupt a cycle,
however, does not wish to traverse in the "cycle coordinate system", but in the programmed
WCS. This is why the SZS is used for the display. For reasons of compatibility, the SZS is
made configurable.
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$P_PFRAME : $P_ISO4FRAME : $P_CYCFRAME
Basic logic functions: Axes, coordinate systems, frames (K2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0