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HA0373T Rev Ck May 2017
Chapter 6
TrigOut
-
Diff
- The state of the TRIG port is asserted depending on whether both
the XDIFF and the YDIFF signals coming from the position sensor are below the
Trig Diff Threshold
parameter. If both XDIFF and YDIFF are below the limit, the
state will be the logic state selected in
Triggering Polarity
and conversely if either
of them falls outside these limits, it will assume the opposite logic state. This mode
can be use d to signal whether or not the beam is close to the centre (bea m
aligned) position within a certain margin. In closed loop mode it also indicates that
the controller is capable of tracking the changes in the beam position and maintain
beam alignment. The
Diff Threshold
parameter is specified as a percentage of full
scale, in the range 1% to 99%.
Trig Out - SUM/Diff
- This output mode is a ‘logic AND’ combination of the "Inside
SUM range" and "Below Diff Threshold" conditions described above. Having to
meet both conditions provides a more reliable indication of the normal closed loop
operation when the beam is aligned and in the centre of the position sensor. In this
scenario the SUM signal is within the expected limits (there is sufficient amount of
light hitting the sensor) and both XDIFF and YDIFF are below a certain threshold
(the beam is centrali zed). The second part of the condition, XDIFF and YDIFF
below the threshold can also occur if the beam is blocked.
Polarity
The polarity of the trigger pulse is specified in the appropriate
Polarity
parameters as
follows:
Active is High
- The active state of the trigger port is logic HIGH 5V (trigger output
on a rising edge).
Active is Low
- The active state of the trigger port is logic LOW 0V (trigger output
on a falling edge).
