National Instruments DAQ M Series - Manual (Page 45)

Chapter 4 Analog Input
© National Instruments Corporation 4-21 NI 6236 User Manual
AI Start Trigger Signal
Use the AI Start Trigger (ai/StartTrigger) signal to begin a measurement
acquisition. A measurement acquisition consists of one or more samples. If
you do not use triggers, begin a measurement with a software command.
After the acquisition begins, configure the acquisition to stop:
• When a certain number of points are sampled (in finite mode)
• After a hardware reference trigger (in finite mode)
• With a software command (in continuous mode)
An acquisition that uses a start trigger (but not a reference trigger) is
sometimes referred to as a posttriggered acquisition.
Using a Digital Source
To use ai/StartTrigger with a digital source, specify a source and an edge.
The source can be any of the following signals:
• Input PFI <0..5>
• RTSI <0..7>
• Counter n Internal Output
• PXI_STAR
Note Refer to the NI 6236 Specifications for the minimum allowable pulse width and the
propagation delay of PFI <0..5>.
The source also can be one of several other internal signals on your DAQ
device. Refer to Device Routing in MAX in the NI-DAQmx Help or the
LabVIEW 8.x Help for more information.
You also can specify whether the measurement acquisition begins on the
rising edge or falling edge of ai/StartTrigger.
Routing AI Start Trigger to an Output Terminal
You can route ai/StartTrigger out to any output PFI <6..9> or RTSI <0..7>
terminal.
The output is an active high pulse.
The device also uses ai/StartTrigger to initiate pretriggered DAQ
operations. In most pretriggered applications, a software trigger generates
ai/StartTrigger. Refer to the
AI Reference Trigger Signal section for a