Overloading PCI bus bandwidth with 4 daq cards?

[creagle]

I am attempting to acquire data using one relatively new PC.  I have 4 DAQ Cards.. NI PCIe-6323 (x3) and NI PCIe-6353

Each one is sampling data at 800Hz, the first card is reading 32 channels, the second 32 channels, the third 24 channels, and the fourth 4 channels.

I'm also using VISA to communicate with a USB device

I can simultaneously acquire data from 3 daq cards and operate the usb device

I can simultaneously acquire data from all 4 daq cards without the usb device

However, I can't acquire data from all 4 cards and operate the usb device simultaneously.  In this configuration all the data is acquired from the daq cards before the operate signals are sent to the usb device.  Also, when I acquire from 4 daq cards at the same time my status bar/wait timer does not update in real time.

Have I hit the limit of the hardware of the computer?  Any suggestions about how to fix or debug this issue would be much appreciated

[afrowizard]

Hello,

What USB device are you using? Also, when you say that the USB works with 3 pcie cards, are those all the 6323's or does it also work with 2 6323's and 1 6353?  

This sounds like you might be overloading your PC's power supply What wattage is it?  Have you been able to test it on a different machine?

-Mason

Applications Engineer

National Instruments

[creagle]

Thank you very much for the suggestion.  The USB device is a serial to usb adapter for a stepper motor controller (the motor has a separate power supply).  I've attached the specs for the power supply.  Swapping the power supply would probably be an easier switch than trying another computer because of all of the setup we have involved in this one (Labview and DAQmx).  If this looks woefully inadequate, can you suggest some specs for our setup?  Thank you again

[afrowizard]

After a bit of research, the usb and pci power sources are independent, so if you can run 4 pci cards then you should also be able to add a usb device.  Is this the only device that causes the error?  This might simply be a driver issue--when this happens what do you see in MAX and in Windows Device Manager?

[creagle]

The USB device works fine with only 3 daq cards (doesn't matter which ones), this is our work around right now.  We switch the daq cards and have to run the tests twice to get all of the information.

I have no issues in the device manager.  MAX is also not showing any errors, is there a way to troubleshoot running all of these devices in MAX that would supply some more information? 

[afrowizard]

Could you give us the specs on your system?  OS, LabVIEW version, DAQmx version, MAX version etc.  Sometimes not having the correct DAQmx driver can cause unexpected behavior 

[creagle]

We are running Windows 7, Labview 2011 (11.0), MAX v5.3.1f0

DAQmx version appears to be 9.5.5 however I'm not 100% on this.  I found this through MAX.  Is there a better way to check this?

NI Visa appears to be version 5.2

[afrowizard]

MAX is the best way to check!  You should download the latest DAQmx driver and give that a shot:

http://joule.ni.com/nidu/cds/view/p/id/4240/lang/en

[xband]

Did you ever solve this?  I had a similar issue and it was the PC power supply.  

[wwalton13]

What power was your old supply, and what kind of power did it end up taking to drive all the devices?