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10MHz Ref Out only 11Hz on NI-5820

I have a PXIe-1075 chassis with a NI-5820 VST in a slot. I have configured the onboard 10 MHz synchronization clock to be exported to the Ref Out port on the NI-5820 front panel using the "niRFSG Export Signal.vi". When I look at the output on a bench scope the frequency is ~11Hz not 10MHz. Per the example "niRFSG Export Signal VI" I have set the signal input to Ref Clock and the output terminal to RefOut. The next VI block in my LabView code is "niRFSG Initiate.vi". Why is the RefOut not 10MHz?

ThanksExportSignal_vi.JPG

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Message 1 of 7
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**** UPDATE ****

I just checked my 10MHz RefOut port on the back of the NI PXIe-1075 chassis. It is only generating ~52Hz, not 10MHz.

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Message 2 of 7
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When you export the ref clock from the chassis to the card, you should be probing "Ref Out" of the 5820, not the port on the back of the PXIe-1075. That's the information I gleaned from the second message. Can you confirm where you are probing for the 10MHz ref clock? If you're exporting using the RFSG VI, you should not be checking the back of the chassis for that signal.

 

Do you have screenshots?

Aulia V.
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Message 3 of 7
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Thanks for responding. I added the second comment to note that I do not seem to be getting a 10MHz reference signal from either of those ports. I re-measured both ports after re-booting the chassis and controller and both ports are showing 52Hz square wave as measured by my bench scope. It is interesting that both ports have the wrong frequency output. I am seeing the same frequency from the RefOut at the back of the PXI 1075 chassis as I am seeing at the RefOut port on the NI PXIe5820 front panel. Even if the NI PXIe5820 RefOut isn't right, the NI 1075 chassis should be, shouldn't it? Also, I think a 10MHz reference output should be +/- 1.75V sinusoidal.

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Message 4 of 7
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Ohhhhh, yeah okay. Something's wrong here if your 1075 chassis is also not showing it. Makes me believe that the internal clock is busted. Not only that, but 50/60 Hz is just ambient noise frequency. I was able to test with a PXIe-1075 chassis and a scope just to make sure that don't have to manually configure something in software and was able to see the 10M clock properly:

 

forum.PNG

 

1. How are you measuring these? I know you're measuring with a bench scope but the back of the 1075 is BNC. Are you using an adapter or any sort to the scope? 

2. Do you have another chassis to test it's REFCLK Out?

Aulia V.
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Message 5 of 7
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I have a cable that is terminated with BNC on both ends. Bench scope is set to 50ohm. Amplitude looks right, just the frequency is off. I'm not sure if there is some setting to enable the RefOut or not. No other chassis available to compare.

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When I took the screenshot, I was able to confirm that there is no setting to enable the RefOut of the PXI chassis. Is there another card that you can either check the RefOut through exporting a signal or even a card that is able to generate a 10MHz clock on its own? 

 

Sounds like it's broken :/

Aulia V.
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