Slow data acquistion

[JRTritsch]

Disclaimer - I am new to labview

I can't seem to speed up the data acquisition and I am not sure where the bottleneck is. It is (what I think) a fairly simple VI created to read two voltages and output another. I am only able to get recordings at maybe 2-3Hz; which is not very good. Previously the same system was operating on Labview 3 on a apple II taking data at something like 40Khz and signal averaging - which is where I would like to eventually get.

[Francois Normandin]

QUOTE (JRTritsch @ Jul 7 2008, 10:26 AM)

Disclaimer - I am new to labview

I can't seem to speed up the data acquisition and I am not sure where the bottleneck is. It is (what I think) a fairly simple VI created to read two voltages and output another. I am only able to get recordings at maybe 2-3Hz; which is not very good. Previously the same system was operating on Labview 3 on a apple II taking data at something like 40Khz and signal averaging - which is where I would like to eventually get.

Which hardware are you using?

[LAVA 1.0 Content]

My advice:

Start over from scratch, have a look at the examples in the help file. Look for simultanious IO. The express VIs you use are not suitable for hardware clocked timing.

Good luck,

Ton

PS Forget all the express VIs you use except the XY graph.

[sand of time]

Hi

You used too many Express VIs and writing *.lvm file is also very slow. I think you need to programm your software with DAQmx VIs and save data to binary file. When you use the while loop structure, you need to place a time delay. If you don't do that, the CPU usage will be 100%.

Vern Wu

[Neville D]

QUOTE (JRTritsch @ Jul 7 2008, 07:26 AM)

Disclaimer - I am new to labview

I can't seem to speed up the data acquisition and I am not sure where the bottleneck is. It is (what I think) a fairly simple VI created to read two voltages and output another. I am only able to get recordings at maybe 2-3Hz; which is not very good. Previously the same system was operating on Labview 3 on a apple II taking data at something like 40Khz and signal averaging - which is where I would like to eventually get.

Check the sample rate, and whether you are waiting to acquire all the samples before displaying.. (I don't have LV at the moment to look at your example).

Neville.