Siemens SINUMERIK 840Di Function Manual page 839

A separate data block _N_NC_UFR is used to archive global frames.
The block requested by the HMI is created if the machine data
MD18601 $MN_MM_NUM_GLOBAL_USER_FRAMES
or
MD18602 $MN_MM_NUM_GLOBAL_BASE_FRAMES
has a value greater than zero.
Channel-specific frames are saved in data block _N_CHANx_UFR.
In certain circumstances, alarms could be triggered when reintroducing saved data, if the
frame affiliates, be they NCU global or channel-specific, have been changed using machine
data.
Data backup always takes place in accordance with the axis configuration set in the machine
data, not in accordance with the currently valid geometry axis assignment.
2.4.12 Positions in the coordinate system
The setpoint positions in the coordinate system can be read via the following system
variables. The actual values can be displayed in the WCS, SZS, BZS or MCS via the PLC.
There is a softkey for actual-value display in MCS/WCS. Machine manufacturers can define
on the PLC side, which coordinate system corresponds to the workpiece coordinate system
on their machines. The HMI requests the appropriate actual values from the NCK.
$AA_IM[axis]
The setpoints in the machine coordinate system can be read for each axis using the
variables $AA_IM[axis].
$AA_IEN[axis]
The setpoints in the settable zero system (SZS) can be read for each axis using the
variables $AA_IEN[axis].
$AA_IBN[axis]
The setpoints in the basic zero system (BZS) can be read using the variable $AA_IBN[axis].
$AA_IW[axis]
The setpoints in the workpiece coordinate system (WCS) can be read using the variable
$AA_IW[axis].
Axis Types, Coordinate Systems, Frames (K2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed Description
2.4 Frames
2-109