© National Instruments Corporation 31 NI cDAQ-9178/9174 User Guide and Specifications
Figure 19. do/PauseTrigger with Other Signal Source
Using a Digital Source
To use do/PauseTrigger, specify a source and a polarity. The source can be a PFI signal or one of several
other internal signals on the NI cDAQ-9178/9174 chassis.
You also can specify whether the samples are paused when do/PauseTrigger is at a logic high or low
level. Refer to the Device Routing in MAX topic in the NI-DAQmx Help or the LabVIEW Help for more
information.
The NI-DAQmx Help is available after installation from Start»All Programs»National Instruments»
NI-DAQ»NI-DAQmx Help. To view the LabVIEW Help, select Help»Search the LabVIEW Help in
LabVIEW. Alternately, to download the LabVIEW Help, go to ni.com/manuals.
Using an Analog Source
Some C Series I/O modules can generate a trigger based on an analog signal. In NI-DAQmx, this is
called the Analog Comparison Event, depending on the trigger properties.
When you use an analog trigger source, the samples are paused when the Analog Comparison Event
signal is at a high or low level, depending on the trigger properties. The analog trigger circuit must be
configured by a simultaneously running analog input task.
Getting Started with DO Applications in Software
You can use the NI cDAQ-9178/9174 chassis in the following digital output applications:
• Single-Point (On-Demand) Generation
• Finite Generation
• Continuous Generation
For more information about programming digital output applications and triggers in software, refer the
LabVIEW Help or to the NI-DAQmx Help.
The NI-DAQmx Help is available after installation from Start»All Programs»National Instruments»
NI-DAQ»NI-DAQmx Help. To view the LabVIEW Help, select Help»Search the LabVIEW Help in
LabVIEW. Alternately, to download the LabVIEW Help, go to
ni.com/manuals.
Digital Input/Output Configuration for NI 9401
When you change the configuration of lines on a NI 9401 digital I/O module between input and output,
NI-DAQmx temporarily reserves all of the lines on the module for communication to send the module
a line configuration command. If another task or route is actively using the module, to avoid interfering
with the other task, NI-DAQmx generates an error instead of sending the line configuration command.
During the line configuration command, the output lines are maintained without glitching.
Pause Trigger
Sample Clock
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