Delta Tau GEO BRICK LV Reference Manual
Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables
191
Note:
Isx93 contains the address of the register that holds the time-base value (it is a
pointer to that register). Isx93 does not contain the time-base value itself.
pointer to that register). Isx93 does not contain the time-base value itself.
Isx94 Coordinate System x Time Base Slew Rate
Range:
0 - 8,388,607
Units:
2
-23
msec / servo cycle
Default:
1644
Isx94 controls the rate of change of the time base for Coordinate System x. It effectively works in two
slightly different ways, depending on the source of the time base information. If the source of the time
base is the % command register, then Isx94 defines the rate at which the % (actual time base) value will
slew to a newly commanded value. If the rate is too high, and the % value is changed while axes in the
coordinate system are moving, there will be a virtual step change in velocity. For this type of application,
Isx94 is set relatively low (often 1000 to 5000) to provide smooth changes.
slightly different ways, depending on the source of the time base information. If the source of the time
base is the % command register, then Isx94 defines the rate at which the % (actual time base) value will
slew to a newly commanded value. If the rate is too high, and the % value is changed while axes in the
coordinate system are moving, there will be a virtual step change in velocity. For this type of application,
Isx94 is set relatively low (often 1000 to 5000) to provide smooth changes.
Note:
The default Isx94 value of 1644, when used on a card set up with the default servo
cycle time of 442
cycle time of 442
sec, provides a transition time between %0 and %100 of one
second.
If there is a hardware source (as defined by Isx93), the commanded time-base value changes every servo
cycle, and typically the rate of change of the commanded value is limited by hardware considerations
(e.g. inertia). In this case, Isx94 effectively defines the maximum rate at which the % value can slew to
the new hardware-determined value and the actual rate of change is determined by the hardware. To keep
synchronous to a hardware input frequency, as in a position-lock cam, Isx94 should be set high enough
that the limit is never activated. However, following motion can be smoothed significantly with a lower
limit if total synchronicity is not required.
cycle, and typically the rate of change of the commanded value is limited by hardware considerations
(e.g. inertia). In this case, Isx94 effectively defines the maximum rate at which the % value can slew to
the new hardware-determined value and the actual rate of change is determined by the hardware. To keep
synchronous to a hardware input frequency, as in a position-lock cam, Isx94 should be set high enough
that the limit is never activated. However, following motion can be smoothed significantly with a lower
limit if total synchronicity is not required.
Isx95 Coordinate System x Feed Hold Slew Rate
Range:
0 - 8,388,607
Units:
2
-23
msec / servo cycle
Default:
1644
Isx95 controls the rate at which the axes of Coordinate System x stop if a feed hold command (H) is given,
and the rate at which they start up again on a succeeding run command (R or S). A feed hold command is
equivalent to a %0 command except that it uses Isx95 for its slew rate instead of Isx94. Having separate
slew parameters for normal time-base control and for feed hold commands allows both responsive ongoing
time-base control (Isx94 relatively high) and well-controlled holds (Isx95 relatively low).
and the rate at which they start up again on a succeeding run command (R or S). A feed hold command is
equivalent to a %0 command except that it uses Isx95 for its slew rate instead of Isx94. Having separate
slew parameters for normal time-base control and for feed hold commands allows both responsive ongoing
time-base control (Isx94 relatively high) and well-controlled holds (Isx95 relatively low).
Note:
The default Isx95 value of 1644, when used on a card set up with the default servo
cycle time of 442
cycle time of 442
sec, provides a transition time between %100 and %0 (feed
hold) of one second.
Isx96 Coordinate System x Circle Error Limit
Range:
Positive floating-point
Units:
User length units
Default:
0 (function disabled)
In a circular arc move, a move distance that is more than twice the specified radius will cause a
computation error because a proper path cannot be found. Sometimes, due to round-off errors, a distance
computation error because a proper path cannot be found. Sometimes, due to round-off errors, a distance