ADLINK USB-2405 - Manual (Page 44)

34 Operation
External Analog Trigger
The analog multiplexer can select one input channel as the analog
trigger source. That is, one of 4 input channels 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 24-bit. In external analog trigger mode, the first
acquired data starts with a delay time of 1/(sampling rate).
Below-Low Analog Triggering
As shown, the trigger signal is generated when the input ana-
log signal is less than the Low_Threshold voltage.
High_Threshold setting is not used in this triggering situation.
Figure 3-6: Below-Low Analog Triggering
Above-High Analog Triggering
As shown, the trigger signal is generated when the input ana-
log signal exceeds the High_Threshold voltage.
Low_Threshold setting is not used in this triggering situation