Hi,
I am a beginner in using Labview. As a part of my project I need to do some measurement of vibrations. I have NI cRIO 9074 control board and module card NI 9239 (2 pieces). On input channels NI 9239 I receive input from acceleration sensors (SILICON DESIGNS). I need to make an application in Labview, which would do the acquisition of data from these sensors (sampling of analog signal from the input) with frequency of minimum 1 kHz, and which would then write this measured data to the disk.
I managed to connect the hardware and start the system. I wrote the whole application for acquisition in RT mode, but the problem occurs in achieving the desired frequency. In order to achieve sampling frequency of 1 kHz I need to have a loop which takes no longer than 1ms to complete each iteration. But due to the complexity of the task and number of operations, my program needs 3-4 ms for one iteration, and therefore my sampling frequency falls to 250-333 Hz. I already analyzed my program, and I have simplified it to the maximum. I concluded that the biggest time loss is in writing the data to the file. I used Shift Registers and writing to an Array (in the link below there is an example, its for logging only 4 channels but the principle is the same). I have also tried writing the data with TDMS but I don’t get better results.
I thought that FPGA programming will make it possible to achieve what I want, so I tried it also. But I didn’t succeed. I used hybrid approach (target to hots), and FPGA provides very fast reading of data from the sensors. But since the data saving operation is done in host, on RT, again it needs too much time to write this data to the disk. I thought about making a FIFO buffer and to log the complete measurements into it, and to write to the disk after the measuring is over. But I don’t know if it’s even possible due to the big amount of data, or if it is possible to do something like that with FIFO...
So if you could please help me, I’m out of ideas?
Has anyone done some similar applications?
Is my approach to the problem good, do you have any suggestions?
Should I use RT or FPGA module?
If you have any example, suggestion, any help is welcome.
Thanks,
s.m.
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