CEO: Dr. Bernt Götz • phone +493641/66880 • fax +493641/668866 • www.piezosystem.com
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10.4. output of trigger signals
Trigger signals allow us to get an electrical signal when a position is reached or crossed. The
trigger points refer to the measured value (stroke or tilt). The trigger is low-active, i.e. a high/low
edge shows that you have reached a trigger point.
The active stroke/tilt-range for trigger
generation is given by “trgss” (start (lower) position) and
“trgse” (end (upper) position). The interval between the trigger points is given by “trgsi”. It is
possible to get trigger signals at the rising edge (trgedge,channel,1), the falling edge
(trgedge,channel,2) or both edges (trgedge,channel,3). To disable the trigger generation set
trgedge,channel,0.
The measurement unit for trgss, trgse, trgsi is the actuator specific unit (e.g. µm or mrad), the
length of a trigger signal can be set to multiples of 20 µs (standard is 1*20 µs).
Take care that is there no overlap between two trigger impulses. If this occurs, you must minimize
the length of the impulses (trglen,channel,1), or decrease the movement speed of the actuator.
Furthermore, you must be sure that the trigger range (between trgss and trgse) passes through
plus 0.2% of the total stroke, otherwise no trigger will be generated because no change between
the rising and falling edges will be detected.
Caution:
Do not activate trigger function in sweep mode.
Example (trgedge = 1 to 3):
An actuator with a closed loop stroke of 80 microns is used as follows: rising edge
(
trgedge,channel,1
), start point 10 microns (
trgss,channel,10
) end point (
trgse,channel,30
) and
interval 5 microns (
trgsi,channel,5
), i.e. trigger points are at 10, 15, 20, 25, 30 microns. After
reaching Position 10 microns (from a lower position; rising edge!) the trigger is set and the next
trigger point will be calculated (15 microns), the trigger output will be reset after n*20 µs
(
trglen,channel,n
) and the trigger function is waiting to reach the next trigger position (15 microns)
and so on. After reaching the 30 microns position, the next Trigger position is set to 10 microns,
the trigger impulse will be generated when the 10 microns position is reached from a lower position
than 10 microns (rising edge).
10.4.1. extended trigger functions
trgedge = 4 / 5 / 7:
trgedge,channel,4: put out a trigger at each reversal of motion
trgedge,channel,5: the output is related to trgedge,channel,4 inverted. No parameters are needed.
trgedge,channel,7: A short trigger signal of n * 20µs at each reversal motion is generated
(parameter n: trglen).
sketch 10: trgedge = 4
