Synching and Triggering across multiple RT chassis with PXIe-6674T

[swatts]

Hi,

I'm struggling to untangle this but I start with the equipment and the requirement.

I have lots of PXIe-1085 chassis with 8135 RT controllers in them. They are packed with PXIe-5160 scope cards and each has a PXIe-6674T Timing card in it.

I want to set it up as a master/slave with the master setting the trigger for the slaves and synchronising the timings for the slaves too. Essentially a single triggered, synchronised hi-channel oscilloscope.

I'm getting a bit confused with the nomenclature of the various inputs/outputs and other options available to me here.

From what I can gather I want to output the OCXO from the 6674T and input it back into the master and slaves as the main clk. (I'm assuming this is source terminal Oscillator but am struggling to confirm it)

To do this I'm guessing I should take ClkIn and route it to PXI_Clk10_In (externally wired so that master and slaves all have the same lead length)

I have similar issues with the triggering, I have a nice reference trigger pulse output on PFI1 of the 6674T with the intention of using it on the slaves as my trigger input (on PFI0) which I then route on PXI_Trig0 along the backplane (this doesn't work)

For the individual chassis do I then use NI-TClk to route these lines along the entire 18 slot chassis? (I have 1 chassis working fine in this manner)

So state of play so far is that I have a nice 10Mhz signal on the ClkOut of the Master 6674T and a trigger pulse on PFI1, but the slaves are studiously ignoring me (I also suspect that the master is not using the OCXO clk but cannot confirm that)

Any help gratefully accepted, I've been at this a little while now

Love Steve

[edjones93]

Hello,

I am Ed at National Instruments Technical Support. I'm happy to assist you with your query today.

In my research I have found the following articles which describe synchronization with multiple chassis':

1. http://www.ni.com/white-paper/10014/en/

2. http://www.ni.com/white-paper/51922/en/

3. http://digital.ni.com/public.nsf/allkb/DF5949190F497AF486257B1A005B02CE?OpenDocument

4. http://www.ni.com/datasheet/pdf/en/ds-261

Is there a specific error code you are receiving or does the behaviour you require just not appear? Note: from the literature provided above ClkOut of the Master 6674T should also be wired to ClkIn for the Master 6674T as well as each Slave so you are correct in this assessment.

With regards to the triggering not working, is there a specific error for this also or a more detailed explanation for this missing behaviour? Reviewing Page 2 of link 4 above, this route should be possible so this. From link 2 this actually suggests to wire PFI1 on the Master 6674T to PFI1 on the slave 6674T PFI1 and also to wire PFI0 from the Master 6674T to the slave PFI0 6674T where PFI0 is the sync pulse.

I hope that this is helpful and you are successful in your application.

Best regards,

Ed

[swatts]

Hi Ed,

Thanks for replying.

I spent yesterday with a Systems Engineer and now have some code that works, I have to say the SE worked really, really hard (8 hours) to make it work and the code is quite involved. This is surprising to me as I would expect it to have been a lot easier, being a pretty basic requirement.

I'll post the solution and LabVIEW code after I have rebuilt the system in my office and tested it and made a few notes. The results are astonishingly good!

The help and support I got yesterday was exceptional so Kudos to NI (it's why we use your kit), but my feeling is that this shouldn't have been so difficult and I definitely wouldn't have been able to do it without leaning on you guys!

Many Thanks

Steve

[edjones93]

Hi Steve,

That's great to hear! Please do, even possibly add this to the community as an example if you wish.

Each application is different so we try to provide a core methodology which can be supported for as much use cases as possible, of course this can mean that for specific cases the approach can be quite complex.

I look forward to reviewing the solution, synchronization is quite an interesting and tricky subject.

Best regards,

Ed

[swatts]

Here you go Ed

https://decibel.ni.com/content/blogs/labviewramblings/2015/10/01/synchronizing-multiple-chassis

I've tested it using a digital trigger to free up all the scope channels too.

Hope it's useful to someone and many thanks to Sacha Emery for sorting it for me

Steve