Input/Output 06/2005
Danaher
Motion
There is no explicit limit to the number of positions you can have in a PLS,
but the PLS positions must be increasing monotonic (Position2 must be
greater than Position1, Position3 must be greater than Position2, etc.).
10.3.3. Repetition
Interval
PLSREPEAT
allows you to repeat the same PLS after a fixed number of
counts. For example, the figure below shows a PLS that turns on at 0, off at
10 and has a
PLSREPEAT
value of 100:
10.3.4. Polarity
PLSPOLARITY
allows you to control the polarity of the PLS output. The
initial polarity may be specified as 1 or 0, indicating that the output is set to 1
or 0 after the PLS is enabled and when the axis is located between the first
and second PLS positions. If the axis position (when the PLS is enabled) is
not located within this segment, the output polarity is set to 0 or 1, according
to the current position so that when the axis reaches the first segment, the
output polarity is as indicated. The default value for polarity is
0
.
10.3.5. Hysteresis
The MC allows you to apply hysteresis around switch points. Hysteresis
provides a margin in the switching between PLS positions to accommodate
noise in the PLS axis. Set the hysteresis greater than the noise on the axis,
(typically, 5 or 10 counts of encoder is sufficient, less is required for resolver
systems). If you have a hysteresis of 0.01 position units, each transition of
PLS position is moved forward 0.005 units for positive motion and backward
0.005 units for negative motion. If the axis driving the PLS is stopped directly
on a PLS position and the inherent noise on the axis is less than the
hysteresis, the PLS state does not change due to this noise.
10.3.6. Enable and Disable
PLSENABLE
enables or disables the PLS(s). After being defined, a PLS is
disabled. The output is fixed when the PLS is enabled. The PLS output is set
to the defined initial state when the PLS is enabled.
152 Rev
E
M-SS-005-03l