Advantech PCI-1714, Руководство пользователя

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PCI-1714 & 1714UL User Manual 34
Figure 4.5: PCI-1714 Sample Clock Sources
4.4 Trigger Sources
PCI-1714 cards support the following trigger sources for post-, delay-,
about- and pre-trigger acquisition modes:
• Software trigger
• External digital (TTL) trigger
• Analog threshold trigger.
You can define the type of trigger source as rising-edge or falling-edge.
These following sections describe these trigger sources in more detail.
4.4.1 Software Trigger
A software trigger event occurs when you start the analog input operation
(the computer issues a write to the board to begin acquisitions). When
you write the value to analog input trigger flag TRGF on Write
BASE+Eh to produce either a rising-edge or falling-edge trigger, depend-
ing upon the trigger source type you choose. This edge will then act as an
A/D trigger event. For detailed information, please refer to Appendix C.7
Trigger Mode and Source.
4.4.2 External Digital (TTL) Trigger
For analog input operations, an external digital trigger event occurs when
PCI-1714 cards detect either a rising or falling edge on the External A/D
TTL trigger input signal from screw terminal EXT_TRIG on the ADAM-
3909 screw terminal board. The trigger signal is TTL-compatible.