User Manual
E727T0005, valid for E-727
BRO, 2019-06-28
Physik Instrumente (PI) GmbH & Co. KG, Auf der Roemerstrasse 1, 76228 Karlsruhe, Germany Page 76 / 240
Phone +49 721 4846-0, Fax +49 721 4846-1019, Email info@pi.ws, www.pi.ws
Example 3: A pulse on the digital output line 1 is to be generated whenever axis 1 of the stage has
covered a distance of 0.1 µm, as long as axis 1 moves in negative direction in the range of 0.55 µm
to 0.2 µm (start threshold > stop threshold). For reliable activation and deactivation of the trigger
output, the axis motion should start at 0.6 µm and end at 0.15 µm. Send:
CTO 1 2 1 1 3 0 1 1 0.1 1 8 0.55 1 9 0.2
Figure 21: "Position Distance" Trigger Mode with threshold settings for negative direction of motion; here,
the trigger output is not yet disabled reliably at the end of the curve
Filtering for reduction of false triggers
If the peak-to-peak level of the sensor position noise is greater than one fifth of the TriggerStep
value set, this can lead to unwanted generation of multiple trigger pulses at the same position in
"Position Distance" trigger mode. The occurrence of these false triggers can be reduced with the
following parameters:
Only allow the trigger output in one direction within the start/stop threshold values:
Pos. Distance Trig. Single Direction parameter (ID 0x18000300)
To prevent false triggering within the start threshold range also:
Pos. Distance Trig. Filter Time parameter (ID 0x18000301)
or
Pos. Distance Trig. Filter Level parameter (ID 0x18000302)
However, the position precision cannot be retrieved by using the parameters to reduce the trigger
impact of the sensor position noise.
Switch to command level 1 with CCL to have write access to the parameters. To set the
parameters, use SPA or SEP. Furthermore, you can use WPA to copy the current values from
volatile memory to non-volatile memory, where they become the power-on defaults. To read the
parameter values, you can query with the SPA? or SEP? commands.
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