ADLINK Technology USB-1901, User Manual

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42 Operation
4.3.2 External Analog Triggering
The analog multiplexer can select one input channel as the analog
trigger source. That is, one of 16 input channels in single-end
mode (or 8 input channels in pseudo-differential mode) can be
selected as the analog trigger source. An external analog trigger
occurs when the analog trigger signal crosses above (above high)
or below (below low) the pre-defined voltage level. The range of
trigger level is the full-scale range of the selected input channel
and the resolution is 16-bit. In external analog trigger mode, the
first acquired data starts with a delay of 4 microseconds.
Below-Low Analog Triggering
In below-low analog triggering, as shown, the trigger signal is
generated when the input analog signal is less than the
Low_Threshold voltage. High_Threshold setting is not used in
this triggering situation.
Figure 4-4: Below-Low Analog Triggering
Above-High Analog Triggering
In above-high analog triggering, as shown, the trigger signal is
generated when the input analog signal exceeds the
High_Threshold voltage. Low_Threshold setting is not used in
this triggering situation