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x8 PXIe Carrier Card decimating down to x1 rates on PXIe chassis

Currently , our setup is a  PXIe-1071 chassis with a PXIe-8821 controller and x8 PXIe carrier card from Elma electronics with a custom XMC mezzanine frame grabber card. My hope was to validate that our custom XMC framer grabber worked on NI PXIe hardware. The issue we are running into is the received image data is decimated down to 250 mb/s which is PXIe 1x rates. The data should be coming in at double that rate but there seems to be bottle neck somewhere. I know it is not he mezzanine card because we have validated it works on a PCIe carrier card . The techs from ELMA state it must be the PXIe chassis but it supposed to support  PCIe 4x. Is there any way i can force the chassis to output PCIE x4 ? Or do you possibly know where the bottleneck can be?   

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You're correct in saying that the PXIe-1071 does support up to x4 PCIe between the controller slot and each of the three individual card slots. Does the PXIe card from ELMA scale down to support x4 as well as x8? Where are you reading this data back from the frame grabber? Let me know, and we can continue investigating here.





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Hello and thanks for your response.


Yes, the Elma carrier card datasheet states is should scale down to x4 if supported by the mezzanine and chassis. I am using our frame grabber software test tool on the PXIe system to verify the rates. I can also verify the systems is outputting PCIe x1 from the XMC Mezzanine LED lights and the BIOS of the PXIe system. Is there another way to validate the chassis supports PCIe x4 without another PXIe card which supports PCIe  x4? Can i run a internal test somehow? 

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