PCI 6534 problem with input samples

[Seyar]

Hi everyone, I'm using a PCI 6534 for some input and output applications in buffered mode.

I have a simple sampling application using the PCI 6534 board with a sampling rate of 20Ms/s. As you can see int the files below, I want to sample a clock signal generate from an external device. This clock signal is at 100kHz.

Sampling at 20MHz generats a bad spy file as you can see in the file file_bad.txt

Taking into account only one sample per two, I have a good spy file file_good.txt, but with that method I have only half of the samples, so like sampling at 10MhZ instead of 20MHz .

My clock signal is connected to DIOC0 and there is nothing connected to the others lines.

I don't know what is wrong.

Thanks for helping.

[Seyar]

it's better with the right files to understand, sorry.

[Seyar]

Nobody can or want to help me ?

please.......

[Mohamed H]

Hello,

Can you include in the zip file your VI and the method used to write in the two files.

Regards

[Seyar]

thanks for your interest. I use the PCI6534 with VB6, the files are in the "acquisition.zip".

[Seyar]

Hi, my problem seems to be more complicated !

I tried to sample the DIOC0 connected to GND : the samples are 01010101 in stead of 00000000...

More !

I noticed that this problem of having 0101010 in stead of 00000000 is not permanent.

When I start the PCI 6534, alone, with nothing connected to the card, but the GND in the DIOC0, it makes that sampling errors, and after a moment, without changing nothing, the problem dissapear, and the card samples are ok.

Is there a problem with my card ?

The card is a new one I buy since 3 weeks !

Does anyone met this problem ?

Help, please.................!!!

[Mohamed H]

Hello,

I do not have VB6 so I cannot look at your application. How did you configure your task (DIO task or counter task) and what is your source for the GND?

Regards.

[Seyar]

The two code used to make the sampling are in this picture :

the first sample at 20MHz with errors,and I keep only one sample per two.

the sample at 20MhZ also, 

The GND is given by an power supply, and at the oscilloscope the 0V is clean !

The pin 10 of the card (GND) is also connected to GND.

[Mohamed H]

Hello,

Did you try to do the same thing in Measurement & Automation Explorer by creating a task?

Regards.

[Seyar]

Well, well, well !

I tried with the port 0 :  DIOA0 connected to the 0V signal, sampling at  20MHz, and now it's seems to be okkkkkkkkk !

Actually, I realized that when I use the port 2 (DIOC0 connected to the 0V signal), the line IRQ2 outputs the sampling clock, which disturb all the signal that I want to sample, with a lot of spikes at the sampling instant, so giving me bad samples.

Strangely, when I use the port 0, the IRQ1 is not outputed for  that port, so I don't have spikes on the other signals.

Is it the normal working for that card, or I will have a bad surprise in few days ?....