Multifunction daq

[MikhailK]

Hi Imran,

To change the PCI slot of your DAQ card, you need to shutdown your PC, disconnect it from the outlet, take the cover off your PC and pull out the DAQ from one PCI slot and place it into another PCI slot. You can then close your PC cover, connect it back to an outlet and turn it back on.

[Emran]

Hi,

 Sir in this pc there are four pci slots all of those are same and sir the thing you are advising me,i have done lot of time but it did'nt solve the problem.

Sir after having so many experiments to solve the problem,now the problem become clear to me sir and can be described in 2 points.

1.The main problem is that,as it is tried to generate sinewave of frequency more than100Hz(when data transfer mechanism is  set to dma),it can't generate.(mean while when it is not generating the wave but it successfully reads the wave of >100Hz).

2.When data transfer mechanism is being changed from dma to intrupt,it generates successfully the wave but meanwhile if it is tried to read the wave at any of analog inputs,it reads properly only for a few seconds and than it fails to read properly and shows the wave as garbge.

Sir the reason that i think is: !

When transfer mechanism is set to inturrupt,than it is required for cpu to servise those interupts to handle the data,as cpu goes to service those inturrupts(to generate wave at output),meanwhile the the data which is coming at input can not be handelled properly and looks like garbage(because cpu is busy in servicing the interrupt for output)(i think sir.)

Regards

Imran.

[C-Dav]

Hello Imran,

I have a few more things I'd like you to try if possible...

Can you set a DC value at the same rates as you were using in your second tests (125kHz) and see if you get a constant level, or if the value still jumps towards zero periodically?

Also, try running the AI and AO until you see it turn to garbage data, then noise stop the AO task and restart, what happens?  Does it look normal for a few more seconds, or does the garbage immediately resume?

If you have access to an external function generator, it would be great if you can just test the analog input of your daq card to see if the fact that both the AI and AO are running at the same time is causing problems.  This way we can isolate the problem to just the AI or just the AO.

Setting the data transfer mechanism on the AO to interrupts should not effect the data transfer mechanism of the AI, so that shouldn't necessarily explain why we are seeing this behavior.

Regards,

[Emran]

i'll tell you the results soon.

[Emran]

Hi,

sir 3 things u asked me to do

1) To set dc value at the same sampling rate as used for 125hz.

Sir in case of dc voltages sampling rate set option is disabaled at measurements and exp software ,well! it is generating and reading dc voltages accurately nothing is wrong with dc.

2)To  "try running the AI and AO until you see it turn to garbage data, then noise stop the AO task and restart, what happens?  Does it look normal for a few more seconds, or does the garbage immediately resume?"

Sir answer is yes!i mean when when restarted than it look normal for a few more seconds,garbage immediately not resumed.And i restarted again and again its behaviour was same i mean normal for few seconds than garbage.

3) Sir third u asked me to  test the analog input of  daq card  with an external function generator to see if the fact that both the AI and AO are running at the same time is causing problems.

Sir when i applied signal from external function generator,behaviour was the same as above, i mean:

(1)When ai and ao was enabled at the same time(analog output with interrupt data transfer mechanism ),the input waveform(which was applied from function generator) turned into garbage after few seconds.

(2).When ao was disablled and ai was enabled it was reading properly input wave(applied from function generator).

Additionally!

Sir i  observed that when ao was disabled and ai was enabaled than all the things were working well.But as ao was enabled (i mean ao was generating some ac voltages of frequency 125hz and with interupt transfer mechanism) the problem appeared again.

Thanks.

Imran.

[C-Dav]

Imran,

Thanks for doing that testing.  I'm going to take your information to some colleagues and try to determine what's going on here.  In the meantime, could you post here the part number of your card?  This should be available in the right pane when you select your device in MAX, you can attach a screenshot if you prefer.

Regards,

[C-Dav]

Also, for displaying the 2k sine wave, I believe the only problem is the sampling rate (at least in the screenshots you provided) was too low and the samples per channel was too high.

If you set the input as shown here:

It should work fine (at least it does on my end)

[Emran]

Helo,

Sir part number of my device is NI PCI-6251,well i'll reply lator  for other things you advised me in the last post.

Imran.

[C-Dav]

Imran,

Could I also get the serial number?  This should be available in MAX as well:

Thanks,

[Emran]

Hi sir,

Serial number 0X14EAF26.

Sir i did as you recommended and my daq is  writing and reading as well without any problem (in measuremints and automation sofrware ) by your recommended sampling rate and number of samples but when i tried this in my application than the data at analog input of my interest was still looking a disturbed sine wave,sir actualy in my application in that callback function where i was trying to read the sine wave,some other analog inputs were also being read in that callback all those inputs i left floating (no signal was connected).When i commented(disabale) the code related those inputs,input sine wave at the input of my interest became exact and readable sine wave.But sir why one input could be  disturbed by other inputs sir(in my actual application i have to read all those inputs under same callback but for constant magnitude value will be conected to those but every time voltage  may not be paresent at those input,than they can disturb my input used for sine wave).

Sir to demonstrate you now i made a small application for you in which firstly i read only at single input than i read both inputs simmulataneously,when both inputs were read and one of which was left floating(as my real application) than it disturbed other one.I attached the application and screen shots herewith.

Thanks sir for your kind help with the help of your kind advises problem is almost solved ,please carefully look screen shots and give me the soloution why one analog input can be disturbed by other inputs and how can be avoided from.

Thanks Imran.