Aerotech UNIDEX 600 Series, Руководство пользователя

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Parameters U600 User’s Guide
C-116
Aerotech, Inc.
Version 1.4
C.5.4.4. Non Modal G2 / G3 Commands
The example CNC program below illustrates the modal/non-modal nature of the G2 / G3
commands.
G91 G1
G2 I1 ; Generate circular motion
X1 ; Current versions generate the error: “No Offsets in G2/G3
CompatibiltyMode = CompatibiltyMode BOR 0x1 ; set old style active
G2 I1 ; Generate circular motion
X1 ; Old style executes this CNC block as a G1 command
C.5.4.5. Old Style Contouring
The old style contouring mode refers to small changes made in the manner in which G1,
G2 and G3 contours are generated. Both styles are virtually identical. The old style is
maintained only for compatibility with internal Aerotech testing. The user should never
use the old style. Old style is:
1. “Slice lookahead” during decel phase changed from 3 to 2
2. “Slice lookahead” in constant phase suppressed for arcs
C.5.5. Enable1KHzServo
This Global parameter defines the servo-loop update rate for all axes, as either 1 kHz or 4
kHz. Setting this parameter to 1, activates the 1 kHz mode (1 millisecond) while a 0
activates the 4 kHz mode(4 millisecond). This setting reduces the AvgPollTimeSec. This
setting also has no effect on activities run off the interrupt unrelated to the servo loop.
This mode may also be toggled by the G130 / G131 G codes.
Normally, a 4KHz servo-loop update rate is desirable, to give the fastest possible rate of
position error correction, resulting in the highest degree of accuracy to the commanded
motion. This is almost a necessity for systems with one or more axes having a system
resolution of 1 micron or less.
However, if the controller is over-loaded and having difficulty in completing tasks other
than closing the servo loop, then a 1KHz servo-loop interrupt should be considered. This
will be obvious if “CNC Profile Queue Starvation” error message is displayed or motion
is discontinuous. The trade-off is that a 1Khz loop will result in a lower rate of servo loop
update. The AvgPollTimeSec task parameter is an excellent indicator of how much time
is left for operations other than the servo loop.
Conditions that may indicate difficulty in completing tasks other than closing the servo
loop (indicating the need for a 1KHz interrupt) include:
1. Motion Queue Starvation
2. Motion is discontinuous.
3. “Locking up” or slow response of the UNIDEX 600 MMI during motion.
Another use for the 1KHz setting is to reduce noise in low-resolution encoder systems.
When the servo-loop is updated at 4 kHz, and the feedback is of low resolution (greater
than 1 micron step size), the resulting corrections may contain a audible high frequency
oscillation. Selecting the 1 kHz update rate slows done the rate of correction, thus
removing this oscillation.