# Limitations of Using DAQ Cards for Absolute Vibration Measurement in Hydraulic Machines
## 5 Measurement of Absolute Vibrations of Hydraulics Machines Using DAQ Cards, Measurement Setup
### NI 9232  
The following parameters characterize the NI 9232 (produced by National Instruments Inc., Austin, TX, USA) measurement card:  
* resolution: 24 bits;
* number of analog inputs (multiplexed): 3 (pseudo-differential inputs);
* maximum sampling rate: 102.4 kHz;
* measurement ranges: \(\pm\)30 V.  
The test results of the NI 6289 card are presented in Table 7 and Figure 11.  
The value of vibration velocity determined in the test does not exceed 0.1 mm/s at a cut-off frequency of 0.1 Hz. Vibration displacements exceed 200 \(\upmu\)m at a filter frequency of 0.1 Hz. At a cut-off frequency of 2 Hz, the vibration velocity is 0.023 mm/s and vibration displacements do not exceed 5 \(\upmu\)m.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**2 Hz**} & \multicolumn{2}{c}{**1.5 Hz**} & \multicolumn{2}{c}{**1 Hz**} & \multicolumn{2}{c}{**0.5 Hz**} & \multicolumn{2}{c}{**0.25 Hz**} & \multicolumn{2}{c}{**0.1 Hz**} \\ \hline
**Range** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** \\
**(V)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** \\ \hline \(\pm\)10 & 0.016 & 2.74 & 0.018 & 3.85 & 0.024 & 7.45 & 0.031 & 15.85 & 0.039 & 42.85 & 0.041 & 69.66 \\ \(\pm\)5 & 0.009 & 1.60 & 0.011 & 2.34 & 0.013 & 3.75 & 0.019 & 10.58 & 0.022 & 18.84 & 0.024 & 46.06 \\ \(\pm\)2 & 0.004 & 0.73 & 0.005 & 1.00 & 0.006 & 1.88 & 0.008 & 3.99 & 0.010 & 8.97 & 0.011 & 18.08 \\ \(\pm\)1 & 0.002 & 0.39 & 0.003 & 0.56 & 0.003 & 0.97 & 0.005 & 2.93 & 0.006 & 7.29 & 0.007 & 12.31 \\ \(\pm\)0.5 & 0.002 & 0.33 & 0.002 & 0.46 & 0.002 & 0.81 & 0.004 & 2.33 & 0.006 & 5.77 & 0.007 & 13.09 \\ \(\pm\)0.2 & 0.001 & 0.23 & 0.002 & 0.37 & 0.002 & 0.72 & 0.004 & 2.18 & 0.005 & 6.42 & 0.006 & 15.76 \\ \(\pm\)0.1 & 0.001 & 0.23 & 0.002 & 0.38 & 0.002 & 0.75 & 0.004 & 2.02 & 0.005 & 6.3 & 0.006 & 12.05 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Vibration measurement results using the NI 6289 card for different cut-off frequencies of high-pass filters.  
Figure 10: Vibration measurements using the NI 6289 card (National Instruments Inc., Austin, TX, USA) depending on the cut-off frequency of the high-pass filter: vibration velocity (**a**) and vibration displacement (**b**).  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**2 Hz**} & \multicolumn{2}{c}{**1.5 Hz**} & \multicolumn{2}{c}{**1 Hz**} & \multicolumn{2}{c}{**0.5 Hz**} & \multicolumn{2}{c}{**0.25 Hz**} & \multicolumn{2}{c}{**0.1 Hz**} \\ \hline
**Range** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** & **vrms** & **s-p-p** \\
**(V)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** & **(mm/s)** & **(\(\upmu\)m)** \\ \hline \(\pm\)30 & 0.023 & 4.38 & 0.029 & 7.07 & 0.037 & 12.13 & 0.068 & 45.17 & 0.084 & 90.00 & 0.098 & 211.61 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Vibration measurement results using the NI 9232 card for different cut-off frequencies of high-pass filters.