NI-DAQmx: Acquire Analog Input Data Using a Hardware Analog Trigger

I. Description:
This example demonstrates how to acquire a finite amount of data (waveform) using the DAQ device's internal clock when an analog trigger condition is met. It also gives the option to enable pretriggers and specify the number of pretrigger samples.

II. Instructions for Running:
1. Select the physical channel to correspond to where your signal is input on the DAQ device.
2. Enter the minimum and maximum voltage range.
Note: For better accuracy try to match the input range to the expected voltage level of the measured signal.
3. Set the number of samples to acquire per channel.
4. Set the rate of the acquisition
Note: The rate should be AT LEAST twice as fast as the maximum frequency component of the signal being acquired.
5. Set the source of the start trigger.
6. Set the slope and level of desired analog edge condition.
7. Set the number of pretrigger samples if necessary.

III. Block Diagram Steps:
1. Create an analog input voltage channel(s)
2. Set the rate for the sample clock. Additionally, define the sample mode to be finite and set the number of samples to be acquired per channel.
3. Define the parameters for an Analog Start or Reference Trigger.
4. Choose a Reference trigger type if pretrigger samples are necessary.
5. Start acquiring data
6. Use the Read VI to measure multiple samples from N Channels on the device. Set a timeout so an error is returned if the samples are not returned in the specified time limit
7. Stop the task.
8. Call the Clear Task VI to clear the Task after the acquisition is complete.
9. Use the popup dialog box to display an error if any.

IV. I/O Connections Overview:
Make sure your signal input terminal matches the Physical Channel I/O Control. In this case wire your signal to the ai0 pin on your DAQ Device.

Requirements

Filename: 204126b.vi

Software Requirements

Language(s): LabVIEW

Hardware Requirements

Driver: NI-DAQmx 7.5

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