The NI 408x family of DMMs fully supports continuous waveform acquisitions. To configure a DMM to acquire a waveform continuously call the niDMM Configure Waveform Acquisition VI with a 0 wired to the Waveform Points input terminal, as seen below.
Continuous acquisitions cannot be performed with an NI 407x DMM in Waveform Mode. For the 407x family continuous acquisition can only be done when the Operation Mode is set to DMM Mode. Refer to the topic "Continuous Acquisitions" in the NI Digital Multimeters Help, linked below, for more information on how a continuous acquisition is performed with a 407x DMM in DMM mode.
It is possible to take large acquisitions on an NI 407x in waveform mode, but only for a finite time. The LabVIEW shipping example Fetch & Graph Waveform.vi allows the you to perform a finite acquisition that can be aborted by pressing the stop button. To view this example, open the NI Example Finder by selecting Find Examples on the Help menu in LabVIEW. In the NI Example Finder, this example is located in the folder Hardware Input and Output » Modular Instruments » NI-DMM » Acquiring Waveforms.
The maximum length of the acquisition will be
t = Number of Samples / Sample Rate.
Where t is the acquisition length and has a maximum of 149 seconds. For example, if a sample rate of 1.8 MS/s is used then you will be able to acquire 268.2 MSamples (149 seconds * 1.8 MS/s = 268.2 MS). If a sample rate of 500 kS/s is used, you can acquire 74.5 MS (149 seconds * 500 kS/s = 74.5 MS).
If this does not allow you to acquire for a long enough period of time, consider taking a multipoint acquisition with your NI 407x device in DMM mode instead of Waveform mode.
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