Auxiliary axes

from TwinCAT 2.8

Auxiliary axes (also known as Q axes) can be added to an interpolation group in addition to the actual path axes (X, Y & Z). The auxiliary axis can be seen as a type of slave for the path, i.e. it has no direct influence on the path velocity. In addition to the 3 path axes, 5 auxiliary axes can also be interpolated for each channel.

The function block 'CfgBuildExt3DGroup' from TcNcCfg.lib, for example, may be used for adding to the interpolation group from the PLC.

Syntax

The auxiliary axes are addressed as Q1..Q5 from the part program. The numerical value may be assigned directly, or an R-parameter.

Sample 1:

(start position X=Y=Z=Q1=0) 
N10 G01 X100 Q1=47.11 F6000
... 

If an NC block is programmed with one or more path axes and an auxiliary axis, both axes start simultaneously and also reach the destination together.

Swivelling of the auxiliary axes

The term "swivelling of the auxiliary axes" is used if the path length within a motion set is zero. This is often the case during 'swivelling' of a tool, with the feed angle relative to the contour being changed.

Since the path length is zero, there is no link to the path, and the movements of the auxiliary axes are calculated via a virtual path. However, this has no influence on the real path of X, Y and Z, but here too all auxiliary axes are started simultaneously and also arrive at the destination simultaneously.

Here too, the velocity is specified via the F-parameter and now refers to the auxiliary axis with the greatest travel distance.

Sample 1:

(start position X=Y=Z=Q1=Q1=0)
N10 G01 X100 F6000
N20 Q1=100 Q2=200 F3000
... 

In N20, the velocity of Q2 is now 3000 and that of Q1 is 1500, since the travel distance is Q1=Q2/2.