Siemens SINUMERIK 840Di Function Manual page 1113

2.12.21 FC 16: PART_AX positioning of indexing axes
Description of functions
(Do not use for new applications, function is integrated in FC 18 in SW 3.6 and higher.)
FC PART_AX can be used to traverse NC axes defined via machine data as "indexing axes",
also from the PLC.
References:
/FB2/ Description of Functions, Expansion Functions; Indexing Axes (T1)
In order to traverse the indexing axes via the PLC, the traversing check must be activated for
the PLC.
This can be achieved, for example, by calling FC "PART_AX" with activation of the "Start"
parameter.
The FC "PART_AX" then requests checking of the axes from the NC.
The NC feeds back the status of this axis in byte 68 in the associated axis interface (DB 31,
...) (see interface lists).
On completion ("InPos" is True, "Start" changes to zero), the axis check function is switched
to a neutral status by FC PART_AX.
Alternatively, the PLC user program can also request the check for the PLC prior to calling
FC "PART_AX".
By calling this function several times in succession, a better response reaction by the axes
can be obtained as the changeover process in the FC can be omitted.
Activation through the PLC user program is executed in the corresponding axis interface in
byte 8.
After return of the check, the axis can again be programmed by the NC program.
Note
After the FC has been called, ACCU1 contains an error statement by the NCK (but not if the
output parameters are assigned to a data block). This is generally the value 0 (signifies: No
error has occurred). See table 8-48 for the interpretation of other numerical values for error
codes in FC 15.
FC 16 must be called cyclically until the "Active" signal produces an edge transition from 1 to
0. Only when the "Active" signal has a 0 state can the axis concerned be restarted (the next
start must be delayed by at least one PLC cycle). This also applies when the assignment in
data byte 8 has changed.
The function cannot be aborted by means of parameter "Start", but only by means of the
axial interface signals (e.g., delete distancetogo). The axial interface also returns status
signals of the axis that may need to be evaluated (e.g., exact stop, traverse command).
Power Line Basic PLC Program (P3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed description
2.12 Block descriptions
2-201