Reference Manual

PMAC 2 Software Reference
PMAC I-Variable Specification 51
There can be up to eight R/D converters on two ACC-8D Option 7 boards at one
multiplexer address.
Example
Motor 3 has a triple resolver, with each resolver geared down by a ratio of 16:1 from the
resolver before it. The fine resolver is connected to R/D converter 4 at multiplexer address
0 (the first R/D converter on the second ACC-8D Option 7 at address 0). The medium
resolver is connected to R/D converter 5 at this address, and the coarse resolver is
connected to R/D converter 6. The following I-variable values should be used:
I310=$040100 .... ; The 0100 in the low 16 bits specifies
............................ ; multiplexer address 0; the 4 in the high 8 bits
............................ ; specifies R/D converter 4 at this address.
I93=16 ................ ; Specifies 16:1 ratio between medium and fine
I83=16 ; Specifies 16:1 ratio between coarse and medium
See Also
Selecting the Position Loop Feedback (Setting Up a Motor)
I-Variables I9x, Ix03, Ix10, Ix81
ACC-8D Option 7 (R/D Converter) Manual
I89 Cutter Comp Outside Corner Break Point
Range
-1.0 – 0.99999
Units
cos ∆θ
Default
0.99848 (cos 1
o
)
Remarks
I89 controls the threshold between outside corner angles for which an extra arc move is
added in cutter compensation, and those for which the incoming and outgoing moves are
directly blended together.
I89 is expressed as the cosine of the change in directed angle between the incoming and
outgoing moves. As such, it can take a value between -1.0 and +1.0. If the two moves
have the same directed angle at the move boundary (i.e. they are moving in the same
direction), the change in directed angle is 0, and the cosine is 1.0. As the change in
directed angle increases, the corner gets sharper, and the cosine of the change in directed
angle decreases. For a total reversal, the change in directed angle is 180
o
, and the cosine is
-1.0.
If the cosine of the change in directed angle of an outside corner is less than I89 (a large
change in directed angle; a sharp corner), PMAC will automatically add an arc move with
a radius equal to the cutter radius to join the incoming and outgoing moves. This prevents
the cutter from moving too far out when going around the outside of a sharp corner.
If the cosine of the change in directed angle of an outside corner is greater than I89 (a
small change in directed angle; a gradual corner), PMAC will directly blend the incoming
and outgoing moves with its normal blending algorithms. This can provide increased
speed on small angle changes, because an extra segment of minimum TA or 2*TS time is
not added.
Note:
Do not set I89 to +1.0 (or greater). Otherwise, PMAC will try to
add an arc to every blend (even straight lines).
I89 does not affect the behavior at inside corners, where the incoming and outgoing moves
are always blended directly together, regardless of the change in directed angle.