Longer Data Acquisition with NI PXI 5142

[Phaysal]

Hi,

I've a NI PXI 5142. I have read that, with 100MS/s, the longest data it can record is just over 1s. Using the same sampling rate, I wanted to record data for over 10s. Is there anyway of doing it? Can I buy some more memory to do it?

Regards

[jschwartz]

Hi Phaysal,

You are correct - sampling at 100 MS/s with 2 bytes per sample means you are sampling at 200 MB/s so you could sample a little more than 1 second with the 264 MB option of the PXI 5124 (the largest memory option scope).  An option you should take a look at is streaming to disk.  For this, you should take a look at PXI Express and using a RAID array to stream your data directly to a hard drive.  With the NI 8260, our in-chassis RAID drive, you can stream to disk at rates of 200 MB/s.  For 10 seconds of data at 100 MS/s, you will need about 2 GB of space.  For your setup, you should take a look at the following equipment:

PXIe-1062Q

PXIe-5122

NI 8260

ni.com/streaming

The 1062Q, PXIe-8130, and PXIe-5122 will fit in one chassis and meet all of your specifications. 

[Phaysal]

Hi Jim,

I am trying to use 5142 using the example file "niScope EX Save to File - HWS Low Level - Single Channel.vi". I have checked that my device has a 256MB/ch option. By, using 100MS/sec and 8bit/sample, the device should allow me write over 2 seconds of data, but the longest I can record is only 40ms worth of data (40M samples). If I try any longer data recording, it informs of overwriting of data. Am I missing something here? Is there any other example that allows me to write longer data record? Can I use fewer than 8bits/sample to record longer data using 5142?

Regards

[jschwartz]

Hi Phaysal,

You should definitely be able to sample more than this.  What is the error number that you are getting?

[Phaysal]

Hi Jim,

Sorry for replying late, but I got stuck in something else. Anyway, the error number is 0xBFFA4018

Further details are:

Error occured at: niScope Fetch Binary 8.v:1 

"The requested data has been overwritten in memory so it is no longer available"

Status code: -200004

The settings I am using are:

Min Sample rate = 100M

Vertical Range = 4

Binary Sample Width = 8 bits

Is there anyway, I can do this with lesser bits, to get longer data.

Regards

[jschwartz]

Hi Phaysal,

8 bits will be the lowest resolution that you will be able to use with this scope. The attached example will allow you to configure your acquisition for 8 bits and you can set the record length to 200M.  This should get you close to two seconds worth of data. 

[Phaysal]

Thanks Jim....let me give it a try today.

regards

[Phaysal]

Hi Jim,

The example you sent me was for LabView 9, I have 8.5 Installed on my machine. I tried the niScope EX Binary Acquisition.VI file from the included examples folder and it gave me an error 0xBFFA2003 saying Maximum time exceeded before the operation completed.

Did the file you sent was a tweaked version of the original one. Can you re-send it to me for LabView8.5.

Regards

[jschwartz]

Hi Phaysal,

I have attached the VI as a LabVIEW 8.5 VI.

[Phaysal]

Hi Jim,

I tried this version as well, but it gives the same error.

Anyway... I tried the file I was using before (niScope EX Save to File - HWS Low Level - Single Channel.vi) with a lower sampling rate and I can record much longer data. This could be because the on-board memory does not get filled as the samples arrive slowly then the fetch cycle. With higher sampling rate, samples arrive much faster and the fetch cycle does not get enough time. This causes the on-board memory to fill up and over flow.

Now any workaround for this that I can record over 2 sec of data with 100M?

Regards