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A basic requirement of vibration measurements is measuring the level of the signal that an accelerometer returns. The level of the accelerometer signal generally is expressed in root mean square acceleration (g_rms).

Single-Shot Buffered Acquisition

The following block diagram illustrates a VI designed to perform a single-shot acquisition and compute the RMS levels.

The sampling frequency is 10 kS/s. The DAQmx Read (Analog 1D Wfm NChan NSamp) VI returns a buffer containing 1 s of data.

Continuous Signal Acquisition

You can use the block diagram in the previous section with a While Loop to continuously acquire signals from an accelerometer and display the vibration level in a chart. The following block diagram illustrates how to measure the RMS value once every 100 ms and display the results in a strip chart.

Note  Set the restart averaging control on the SVL RMS Level VI to TRUE. Otherwise, the SVL RMS Level VI accumulates intermediate results to compute the RMS vibration level over the entire data acquisition instead of just over the last block of data.

In the previous block diagram, the RMS value is computed based on the last 100 ms of acquired data.