Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 185
During this automatically inserted dwell time (if greater than 0), a coordinate-system “dwell-in-progress”
status bit (Y:$002x40 bit 5, distinct from the motor “dwell-in-progress” status bits from a directly
programmed dwell) will be set.
Isx83 Coordinate System ‘x’ Corner Blend Break Point
Range: -1.0 .. 0.9999 (floating-point)
Units: cosine
Default: 0.0 (disabled)
Isx83, if set to a non-zero value, controls the threshold in Coordinate System ‘x’ between corner angles
for which LINEAR and CIRCLE-mode moves are directly blended together, and those for which the axes
are stopped in between the incoming and outgoing moves for the corner. Isx83 is only used if the
“continuous motion request” (CMR) coordinate-system status/control bit is set to 1 permit blending. (This
can be set by Isx92=0 at the beginning of a motion program, or can be set directly afterwards.) If the
CMR bit is 0 (usually from Isx92=1), no blending occurs between any moves, and Isx83 is not used.
If Isx83 is set to 0.0, no decision on blending is made based on corner angle. In this case, the decision on
blending is made by the “continuous motion request” coordinate-system status/control bit. (If a threshold
corner angle of 90
o
is desired – for which the Isx83 would be 0.0 – Isx83 should be set to a value that is
not exactly 0.0, for example to 0.00001).
Isx83 is expressed as the cosine of the change in directed angle between the incoming and outgoing
moves. (The change in directed angle is equal to 180
o
minus the included angle of the corner.) 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.
The change in directed angle is evaluated in the plane defined by the NORMAL command (default is the
XY-plane); if the corner also involves axis movement perpendicular to this plane, it is the projection of
movement into this plane that matters.
If the cosine of the change in directed angle at a corner is less than Isx83 (a large change in directed
angle; a sharp corner), Turbo PMAC will automatically disable blending between the two moves, and
bring the commanded trajectory to a stop at the end of the incoming move. If Isx81 is greater than 0,
Turbo PMAC then verifies that all motors in the coordinate system are “in position”. Next, if the cosine
of this angle is also less than Isx85, a dwell of Isx82 real-time interrupt periods is executed. Finally, the
outgoing move is automatically executed. From the time the incoming commanded move begins, through
any in-position settling and added dwell, until the commanded outgoing move starts, the coordinate-
system status bit “sharp corner stop” (Y:$002x40 bit 6) will be set.
If the cosine of the change in directed angle at a corner is greater than Isx83 (a small change in directed
angle; a gradual corner), Turbo PMAC will directly blend the incoming and outgoing moves with its
normal blending algorithms.
The operation of Isx83 is independent of the operation of the similar function of Isx99, which controls for
outside corners in 2D cutter-radius compensation whether an arc move will be added based on the change
in directed angle. Isx83 works regardless of whether cutter-radius compensation is active or not, or
whether the corner is an inside or outside corner when cutter-radius compensation is active. If this is an
outside compensated corner with an added arc, the corner angle is considered to be 0 degrees, and so the
corner would always be blended.