ADLINK DAQe-2006 - Manual (Page 79)

Operation Theory 67
Low-Hysteresis analog trigger condition
Figure 4-36 shows the low-hysteresis analog trigger condition,
the trigger signal is generated when the input analog signal
level is less than the Low_Threshold voltage, and the
High_Threshold voltage determines the hysteresis duration.
Note the High_Threshold setting should be always higher then
the Low_Threshold voltage setting.
Figure 4-36: Low-Hysteresis Analog Trigger Condition
External Digital Trigger
An external digital trigger occurs when a rising edge or a falling
edge is detected on the digital signal connected to the EXT-
DTRIG or the EXTWFTRG of the 68-pin connector for external
digital trigger. The EXTDTRIG is dedicated for A/D process,
and the EXTWFTRG is used for D/A process. You can program
the trigger polarity using the software drivers. Note that the sig-
nal level of the external digital trigger signals should be TTL-
compatible and the minimum pulse is 20 ns.
Figure 4-37: External Digital Trigger