Siemens SINUMERIK 840D sl Function Manual page 391

Data backup is always undertaken with machine axis identifiers.
Note
The sag compensation can couple the axis only on one NCU, which can also be traversed
from this NCU either via the part program or via a synchronized action.
These variables are set optionally if the axes (input and output) are not available on the local
NCU. If one uses a channel axis identifier while programming $AN_CEC_INPUT_AXIS and
$AN_CEC_OUTPUT_AXIS, then the system variables $AN_CEC_INPUT_NCU and
$AN_CEC_OUTPUT_NCU become irrelevant.
The control checks whether the two axes can be interpolated from this NCU, i.e., a program
can traverse the axes on this NCU. The axes can be assigned to different channels. Two
axes belonging to different NCUs can also be compensated. Otherwise the control rejects it
with Alarm 17040.
Both axes of compensation must be interpolated on one NCU, i.e., there may be one or two
part programs that traverse the input and output axes on an NCU.
Axis container
The axis container is a grouping of similar axes. An axis from the group can be assigned to a
channel axis. The assignment is variable, so that the axis in the channel always gets a new
axis from the group assigned to it in the course of time. Thus, the part program can be
programmed with one axis and it can gradually move different axes.
Example:
Four spindles are arranged on a drum. Each spindle carries a tool of the turning machine
and it rotates the drum by 90 degrees in each cycle. The tools are transported from one
machining station to the next in this way. The channel of the machining station must program
only one spindle, though a new spindle is always changed. This is an axis container rotation.
The sag compensation can be combined with the axis container if it is in the basic position,
i.e., $AN_AXCTAS == 0. Otherwise the programming is rejected with Alarm 17040.
"YY" is to be coupled to "XX" (see Configuration 2):
1. Programming with channel axis identifier
2. Programming with machine axis identifier
This couples Axis AX2 of NCU1 with Axis 2 of NCU2.
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
$AN_CEC_INPUT_AXIS[0] = (XX)
$AN_CEC_OUTPUT_AXIS[0] = (YY)
$AN_CEC_INPUT_NCU[0]=1
$AN_CEC_INPUT_AXIS[0] = (AX2)
$AN_CEC_OUTPUT_NCU[0]=2
$AN_CEC_OUTPUT_AXIS[0] = (AX2
5.4 Interpolatory compensation
; optional ...
K3: Compensation
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