The DT-9837 and DT-9826 modules include a tachometer input channel. When this device is selected for input, the tach channel will be labeled as "Tachometer Input Channel" on the Input Device dialog.
Enabling this channel will automatically set the calibration to "RPM" and the time series plot will show RPM versus Time. Although the other plot types (Spectrum, Spectrogram, 3-D Surface, Phase) are available, they are not meaningful for the tachometer channel.
A resizeable RPM utility window is also available - click the <Utilities><Tachometer RPM> menu to open this window. It shows the current RPM value.
The RPM value is also available for data logging in the list of output data items.
Refer to the hardware documentation for tachometer signal requirements.
The Tachometer data can be recorded and post processed. It is stored in a wave file as an integer value equal to the actual RPM * 100. The maximum RPM than can be detected is 83,886.