real time problems with 6534

[OZI]

Hi,

in our application we use a PXI-6534 card to aquire datas. With 20MHz we are aquiring 32 bit datas. We have several applications like this which run without problems. But now on the current project we have problem and we don't know why.

When we create test signals and read them in the 6534 we have several failures, that means bits which are not correctly read. Because we have 3,3 Volt signals and the 6534 is a 5V card we expected that the problem is there. But now we are thinking that it can be also that we broke the real time.

Parameters:

- Input data

- clock frequency 20MHz

- 32 bit

Does anyone know if the 6534 is able to aquire datas really up to 20MHz?

Thanks in advance 

Oliver

[Marco_Brauner]

Hi Oliver,

from my point of view, since the specs say that the maximum rate is 80 MHz, this should not be a problem.

But I´m sure that 3.3V logic on a TTL-card will not work reliably.

Marco Brauner NIG

[OZI]

Hello Marco,

About the 3,3 to 5V I agree with you, we are also thinking that this is a bigger problem.

Are you sure that the 6534 can work up to 80MHz with 32 Bit? I am not sure about that. In the specs I read it is only 20MHz at 32 Bits.

Which document do you have ?

 

Greetings

Oliver

[Marco_Brauner]

Hi Oliver,

I was refering to http://sine.ni.com/nips/cds/view/p/lang/de/nid/13505. 

But I saw that the Spec-PDF mentions a maximum internal samplerate of 20 MHz.

And even the 20 MHz are not always possible depending on the width of the words you are transferring.

Two 8-bit finite pattern I/O operations: 20 MHz
Two 16-bit finite pattern I/O operations: 10 MHz
One 8-bit finite pattern I/O, one 16-bit finite pattern I/O: 10 MHz

I think 32- bit should be 20 MHz

Marco

[OZI · Accepted solution]

Hi Marco,

meanwhile we made an independent test.

we created an independent pattern generator which sended a test signal with 3,5V and 20,8MHz and 32Bit to thePXI6534 and checked if the datas are complete. We found out, that there was absolutely no loss of data.

For us this means, that our problem is before the 6534 somewhere inside our electronic.

In general this means, that the 6534 can handle 3,3V signals at 20MHz.

Thanks for your help

Oliver