User`s manual

Operation 43
USB-1900 Series
Figure 4-5: Above-High Analog Triggering
4.3.3 External Digital Triggering
An external digital trigger occurs when a rising or falling edge is
detected on the digital signal connected to the AITG (analog input
trigger) pin. Trigger polarity can be programmed using ADLINK
software drivers.
Figure 4-6: Digital Triggering
4.4 Trigger Modes
Analog input supports post, delay, gate, post trigger with retrigger,
and delay trigger with retrigger modes.
WARNING:
Signal level of the external digital trigger signals should be
TTL-compatible, with a minimum pulse of 20ns.
Positive-edge (rising)
t r i gger ev ent occur s
Negative-edge (f all i ng)
t r i gger ev ent occur s