Export sample clock during acquisition session

[EganM]

Hi,

I am using LabView 2012 to acquire digital data, I am using a PXIe-6556 HSDIO in a PXIe-1062Q chassis.

I need to supply my DUT with a clock and acquire data from it, I have tried many HSDIO acquisition examples but all seem to present the same problem:

When the acquisition begins the sample clock that I am exporting is stopped so all I get back is an array of the same data repeated because my DUT is not being clocked during the acquisition.

The basic procedure I follow is:

1. Open a generation session and configure and export a sample clock on DDC CLK OUT, this works fine and I can see my DUT clocking out Data on a scope in response to the sample clock

2. I open and configure an acquisition session, which when committed (or initiated) stops the exported sample clock.

The particular example I am following is "AC Characterisitics of ADC.vi" 

http://www.ni.com/white-paper/8319/en

Is it not possible to export an onboard generated clock during an acquisition session ?

I'm sure it is a simple task to achieve, the fact that this happens in the LabView examples puzzles me,

Any help appreciated,

Thanks.

[hicksc]

Hi Maurice

What other cards do you have in the chassis? (What are you reading the response using?)

I wonder if this problem is caused by the fact that the 6556 only has one onboard clock, which probably can't be both output and used to clock your inputs at the same time?

I may have overlooked something/misunderstood your problem though.

Kind Regards

[EganM]

Hi Chris,

I also have an 8360 remote contoller, 5422 AWG and 4110 DC PSU cards in the chassis.

My DUT is an ADC, Which I power from the 4110, I apply a sine wave input to the DUT from the 5422 AWG and I clock and acquire the data from the DUT using the 6556 HSDIO card.

I have since discovered that a sample clock can only be exported on the DDC CLK OUT line during an acquisition session, if I export the sample clock on the CLK OUT front panel SMA connector it all works fine. I am happy to use this SMA connector so I am now up and running :).

In reference to the 6556 HSDIO card is it possible to program the high voltage level of the clock exported on the CLK OUT SMA connector ?

The specification states that the minimum High voltage level is 3.1V.

I haven't been able to find any means by which the level can be programmed.

It seems strange to me that such a flexible unit cannot allow the voltage level to be programmed. ?

Thanks,

Maurice.

[hicksc]

Hi Maurice

I think that should be possible using the 'niHSDIO Configure Voltage VI'.

Kind Regards

[EganM]

Hi Chris, I can program the levels of the lines on the DDC connector using the  'niHSDIO Configure Voltage VI', but it doesn't work for the front panel CLK OUT SMA connector, the voltage level here remains at 3.3V.

See code below that sets the voltage levels.

I configure the clock and export it to the CLK OUT sma connector later in the code.

Thanks,

Maurice.

[CheckBenchLTD]

Hi Maurice,

I need for my project to configure the clock out (CLK OUT SMA) voltage (with a PXIe 6556).

Have you succeeded to change the voltage of the output clock?

Thanks

Shimon Zerbib

[MauriceJ]

Hi Shimon,

No, I was unable to change the voltage so I had to reduce the voltage with a voltage divider on my circuit board.

Regards,

Maurice.