Siemens SINUMERIK Series Function Manual page 339

Current state and interpolation right of the axis
With which axis type and interpolation right a possible axis replacement is to be performed,
can be deducted from the system variable $AA_AXCHANGE_TYP[axis].
0: The axis is assigned to the NC program
1: Axis assigned to PLC or active as command axis or oscillating axis
2: Another channel has the interpolation right.
3: Axis is neutral axis.
4: Neutral axis is controlled by the PLC.
5: Another channel has the interpolation right, axis is requested for NC program.
6: Another channel has the interpolation right, axis is requested as neutral axis.
7: Axis active for PLC or as command or oscillating axis, axis is
requested for PLC program.
8: Axis active for PLC or as command or oscillating axis, axis is
requested as neutral axis.
9: Permanently assigned PLC axis, in state of neutral axis.
10: Permanently assigned PLC axis, controlled by PLC, in state of neutral axis.
Permanently assigned PLC axis
in state of neutral axis $AA_AXCHANGE_TYP = 9 and
controlled by PLC, in state of neutral axis $AA_AXCHANGE_TYP = 10
will be assigned to PLC independently of GET and RELEASE permanently.
Whether the axis can also be replaced is displayed via the system variable
$AA_AXCHANGE_STAT[axis].
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
K5: Mode groups, channels, axis interchange
5.4 Axis/spindle replacement
339