•Cont Acq & Graph (buffered) VI—Is similar to the Cont Acq & Chart (buffered) VI, except this VI displays data in a waveform graph.

•Cont Acq to File (binary) VI—Acquires data through circular-buffered analog input and stores it in a specified file as binary data. This process is more commonly called streaming to disk.

•Cont Acq to File (scaled) VI— Is similar to the previous binary VI, with the exception that this VI writes the acquired data to a file as scaled voltage readings rather than binary values.

•Cont Acq to Spreadsheet File VI—Continuously reads data that LabVIEW acquires in the circular buffer and stores this data to a specified file in spreadsheet format. You can view the data stored in a spreadsheet file by this VI in any spreadsheet application.

Simultaneous Buffered Waveform Acquisition

and Waveform Generation

You might discover that along with your analog input acquisition, you also want to output analog data. If so, refer to the Simultaneous Buffered Waveform Acquisition and Generation section in Chapter 7, Analog Output, for more information about simultaneous buffered waveform acquisition and generation.

Controlling Your Acquisition with Triggers

The single-point and waveform acquisitions described in the previous chapters start at random times relative to the data. However, there are times when you need to be able to set your analog acquisition to start at a certain time. One example is if you want to test the response of a circuit board to a pulse input. The pulse input also can be used to tell the DAQ device to start acquiring data. Without this input, you must start acquiring before applying the test pulse. This is an inefficient use of computer memory and disk space because you must allocate and use more than is necessary. Sometimes the data you need might be closer to the front of the buffer and other times it might be closer to the end of the buffer.

You can start an acquisition based on the condition or state of an analog or digital signal using a technique called triggering. Generally, a trigger is any event that starts data capture. There are two basic types of triggering—hardware and software triggering. In LabVIEW, you can use software triggering to start acquisitions or use it with an external device to perform hardware triggering.