How can I acquire the data from 3 separate Channels of SCXI1300 simultaneously?

[RavensFan]

And please don't post bitmap images!  The file size is too large.

Changing the extension from .bmp to .jpg doesn't magically change the file format.

[jingrui]

the SCXI1300 is in a SCXI1000 model, and a big white cord was connected the model and the PCI-6024, when I chose the channels, I chose the ai0:ai2 in the SC1mod3. Is this the answer to your question?

[Dennis_Knutson]

The SCXI-1000 is just the chassis. You've provided the dumb terminal block and the chassis. Do have an actual SCXI signal conditioning module plugged into the chassis?

[jingrui]

I took apart the terminal block and the chassis, and I found a SCXI-1100 multi-channel amplifier bewteen the terminal and the chassis, is that what you want?

[Dennis_Knutson]

YES!

I wish though, that I could understand the error. I don't have an SCXI chassis so I simulated one with an SCXI-1100 and did not get any error when I ran your VI. The SCXI-1100 has either a 166kS/s or 6.6 kS/s max sample rate (depending on whether you are using the filter or not) so the message of a max sample rate of .952 is not something I understand. Sorry, maybe someone with more experience with SCXI can explain.

[Kristen_K.]

Hi jingrui!

I located another thread discussing the same issue with the same module!  I think it may be very helpful.  Post back if you still have questions!

http://forums.ni.com/ni/board/message?board.id=170&message.id=210878&requireLogin=False

Kristen H.

[jingrui]

Hi, Kristen

Thanks for your help. I just went through the information you gave me and  checked the setting for the filter of SCXI-1100, and the jumper stays at the position W2, according to the  manual, this means SCXI has the full bandwidth; and I also tried to move the jumper to W3, it means the filter is a 10kHz lowpass filter, but my program still can not run in this mode, the warning window kept telling me that the maximum sampling frequency is around 1 Hz. 

So I am wondering if there is other possibilities to cause this problem.  

Thanks 

Jingrui

[Brad_K]

Hi jingrui,

The SCXI-1100 has three filter settings: full bandwidth,10 kHz lowpass, and 4 Hz lowpass. In 4 Hz lowpass mode, the filter takes 0.35 seconds to settle, and it has to settle every time the multiplexer switches channels. If you're acquiring from three channels, then your maximum sample rate is going to be 1 / (3 ch * 0.35 S/ch), which is approximately 0.952 S/s.

Why does NI-DAQmx think you are using the 4 Hz lowpass filter setting when in reality you have the jumper set to the full bandwidth or 10 kHz lowpass filter setting? This is because the SCXI-1100 hardware is rather old and doesn't provide software with a mechanism to read the jumper setting. (If it did, it might as well allow software to control the setting using a switch instead of using a jumper.) So you need to run Measurement & Automation Explorer, right-click on the SCXI-1100 module, and select "Properties" to tell NI-DAQmx what jumper setting you are using. Once you do that, you should be able to use higher sample clock rates.

Hope this helps,

Brad

Message Edited by Brad K on 03-27-2009 04:14 PM