Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 193
Isx98 Coordinate System x Maximum Feedrate
Range: Non-negative floating-point
Units: (user position units) / (Isx90 feedrate time units)
Default: 1000.0
Isx98 permits a maximum feedrate to be set for a coordinate system, preventing a program from
accidentally exceeding a specified value. If Isx98 is greater than 0.0, Turbo PMAC will compare each
commanded vector feedrate value from an F command in a motion program to Ix98. If the commanded
feedrate is greater than Isx98, it will use Isx98 instead. This variable permits the system integrator to
place a limit on the speed that a part programmer can command.
Other possible sources of commanded feedrate values, such as Isx86, Isx89, and TM commands, are not
checked against Isx98.
This check of commanded feedrate against Isx98 is done at the programmed move block calculation time,
before any lookahead calculations are done. Lookahead calculations compare individual motor velocities
against Ixx16 limits; they do not check vector velocities.
If Isx98 is set to 0.0, Turbo PMAC will not check the programmed feedrate value against a limit.
See Also:
I-variables Isx86, Isx89
On-line command FRAX
Motion program commands F, FRAX, TM
Isx99 Coordinate System x Cutter-Comp Outside Corner Break Point
Range: -1.0 - 0.9999
Units: cosine
Default: 0.9998 (cos 1
o
)
Isx99 controls the threshold in Coordinate System x 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.
Isx99 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 Isx99 (a large change in
directed angle; a sharp corner), PMAC will add an arc move automatically 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 Isx99 (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.
Isx99 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.
Example:
If it is desired that an arc only be added if the change in directed angle is greater than 45
o
, then Isx99
should be set to 0.707, because cos

= cos 45
o
= 0.707