Reference Manual

PMAC 2 Software Reference
54 PMAC I-Variable Specifiation
I99 Backlash Hysteresis
Range
0 .. 8,388,607
Units
1/16 count
Default
64 (= 4 counts)
Remarks
This parameter controls the size of the direction reversal in motor commanded position
that must occur on any motor before PMAC starts to add the programmed backlash (Ix86)
in the direction of motion. The purpose of this variable is to allow the customer to ensure
that a very small direction reversal (e.g. from the dithering of a master encoder) does not
cause the backlash to “kick in”. I99 thus provides a hysteresis in the backlash function.
The units of I99 are 1/16 of a count. Therefore this parameter must hold a value 16 times
larger than the number of counts reversal at which backlash is introduced. For example, if
backlash is to be introduced after 5 counts of reversal, I99 should be set to 80.
Before I99 was implemented, the backlash hysteresis was fixed at 4 counts, equivalent to
the default I99 value of 64.
Example
With a system in which one count of the master encoder creates 10 counts of movement in
the slave motor, it is desired that a single count reversal of the master not trigger backlash
reversal. Therefore the backlash hysteresis is set to 15 counts, and I99 is set to
15*16=240.
See Also
Backlash Compensation (Setting Up a Motor)
I-Variables Ix85, Ix86
Motor x I-Variables
x = Motor Number (#x, x = 1 to 8)
Motor Definition I-Variables
Ix00 Motor x Activate
Range
0 .. 1
Units
none
Default
I100=1; I200 .. I800=0
Remarks
Ix00 determines whether the Motor x is de-activated (=0) or activated (=1). If activated,
position, servo, and trajectory calculations are done for the motor. An activated motor
may be enabled – either in open or closed loop – or disabled (killed), depending on
commands or events.
If Ix00 is 0, not even the position calculations for that motor are done, so a P command
would not reflect position changes. Any PMAC motor not used should be de-activated, so
PMAC does not waste time doing calculations for that motor. The fewer motors are
activated, the faster the servo update time can be.
Note:
Do not use Ix00 to kill a motor. Changing Ix00 from 1 to 0 leaves
the motor outputs in whatever state they happened to be in at that
moment.
See Also
On-line commands K, <CTRL-K>, A, <CTRL-A>, J/