How Do I Output an Arbitrary Waveform?

NI VirtualBench Help

Edition Date: January 2017

Part Number: 371526G-01

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1. On the FGEN panel, click on the ARB button.
2. Use the Browse button under Waveform Data File to open a data file.
3. Select an Output.
4. Adjust Gain and DC Offset if needed.

The following types of Waveform Data files are supported:

• Text (.txt) with one value per line. Values are in volts. Units are omitted. This type of file produces only one waveform. (sample.txt)
• CSV files (.csv) where each column has a value for each waveform. Values are in volts. Units are omitted. (sample.csv)
• CSV Pitch files (.csv) obtained from PhysioBank at physionet.org. (sample2.csv)

Why does the value of gain and offset change when I load a different data file or select a different output?

When you load a new data file, or select a different output, the gain and offset automatically reset to a gain of 1 and an offset of 0.

If the waveform has values outside the range ±12 V, the VirtualBench keeps offset at zero and uses the maximum gain possible to keep the output inside the range.

Why do gain and offset ranges vary from one data file to another?

The maximum output range supported by the device is ±12 V. In order to keep the output in range, VirtualBench considers the maximum and minimum values of the waveform loaded from the file. When deciding the range values for gain, VirtualBench considers the current value of the offset, and when deciding the range values for offset, VirtualBench considers the current value of the gain. A change in one affects the range of the other.