Delta Tau GEO BRICK LV Reference Manual
Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables
192
slightly larger than twice the radius is given (for a half-circle move), and it is desired that this not create
an error condition.
an error condition.
Isx96 allows the user to set an error limit on the amount the move distance is greater than twice the
radius. If the move distance is greater than 2R, but by less than this limit, the move is done in a spiral
fashion to the endpoint, and no error condition is generated. If the distance error is greater than this limit,
the program will stop at the beginning of the move. Turbo PMAC will set this coordinate system’s circle
radius error status bit.
radius. If the move distance is greater than 2R, but by less than this limit, the move is done in a spiral
fashion to the endpoint, and no error condition is generated. If the distance error is greater than this limit,
the program will stop at the beginning of the move. Turbo PMAC will set this coordinate system’s circle
radius error status bit.
If Isx96 is set to 0, the error generation is disabled and any move distance greater than 2R is done in a
spiral fashion to the endpoint.
spiral fashion to the endpoint.
Example:
Given the program segment:
Given the program segment:
INC CIRCLE1 F2
X7.072 Y7.072 R5
X7.072 Y7.072 R5
Technically no circular arc path can be found, because the distance is SQRT(7.072
2
+7.072
2
) = 10.003,
which is greater than twice the radius of 5. However, as long as Isx96 is greater than 0.003, PMAC will
create a near-circular path to the end point.
create a near-circular path to the end point.
Isx97 Coordinate System x Minimum Arc Length
Range:
Non-negative floating-point
Units:
Semi-circles (
radians; 180 degrees)
Default:
0 (sets 2
-20
)
Isx97 sets the threshold between a short arc and a full circle for CIRCLE mode moves in Turbo PMAC’s
Coordinate System x. Isx97 is expressed as an angle, with units that represent a fraction of a half-circle.
It represents the smallest angle that can be covered by a programmed arc move.
Coordinate System x. Isx97 is expressed as an angle, with units that represent a fraction of a half-circle.
It represents the smallest angle that can be covered by a programmed arc move.
Any programmed CIRCLE-mode move with an IJK-vector representation of the center that covers an
angle smaller than Isx97 is executed as a full circle plus the programmed angle change. Any such move
which covers an angle greater than Isx97 is executed as an arc smaller than a full circle.
angle smaller than Isx97 is executed as a full circle plus the programmed angle change. Any such move
which covers an angle greater than Isx97 is executed as an arc smaller than a full circle.
The purpose of Isx97 is to support the circle programming standard that permits a full-circle move to be
commanded simply by making the end point equal to the starting point (0-degree arc), yet allow for
round-off errors.
commanded simply by making the end point equal to the starting point (0-degree arc), yet allow for
round-off errors.
Most users will be able to leave Isx97 at the default value of one-millionth of a semi-circle. This was
formerly the fixed threshold value. However, some users may want to enlarge the threshold to
compensate for round-off errors, particularly when using cutter-radius compensation in conjunction with
full-circle moves. Remember that no arc covering an angle less than Isx97 can be executed.
formerly the fixed threshold value. However, some users may want to enlarge the threshold to
compensate for round-off errors, particularly when using cutter-radius compensation in conjunction with
full-circle moves. Remember that no arc covering an angle less than Isx97 can be executed.
If a full-circle move is commanded with cutter compensation on, and the blending from the previous
move or into the next move creates a compensated outside corner without adding an arc (see Isx99),
PMAC will extend the compensated move past a full circle. If Isx97 is too small, it may execute this as a
very short arc, appearing to miss the move completely. Isx97 may have to be increased from its effective
default value to cover this case.
move or into the next move creates a compensated outside corner without adding an arc (see Isx99),
PMAC will extend the compensated move past a full circle. If Isx97 is too small, it may execute this as a
very short arc, appearing to miss the move completely. Isx97 may have to be increased from its effective
default value to cover this case.
For backward compatibility reasons, if Isx97 is set to 0, a threshold value of 2
-20
(about one-millionth) of
a semi-circle will be used.