DIfference FlexRIO 7976R & 7975R

[SteClaKUL]

I can't find any difference between the FlexRIO 7975R and FlexRIO 7976R.

[Sam_Sharp]

I would give my local NI sales office a call to be sure, but it looks like the 7976R has a Host streaming rate of 3.2GB/s whereas the 7975R has a rate of 1.7GB/s. This information was only on the product pages and I couldn't see any difference in the PDF manuals/specifications - so I suspect one of them might be incorrect (hence the suggestion to call NI sales).

[SteClaKUL]

Thanks for the fast response !! I also couldn't see any difference in the manuals/specs, hence my question.

[Michael_NIUK]

Hi there,

The 7975R has an x4 PXI express connection, whereas the 7976R has an x8 connection, allowing for higher bandwidth to the host.

You can see this on page 4 of the specifications for the two cards, beyond this, i cannot see any differences;

NI PXIe-7975R Specifications

NI PXIe-7976R Specifications

If you would like to discuss these cards in more detail, give us a call on (+44) 1635 523 545

I hope this has helped!

-Michael

[SteClaKUL]

Hi Michael, thanks a lot for your answer! I didn't notice this when reading the specs.
The difference in connection that you mention, this is a hardware difference?

[Michael_NIUK]

Hi,

Yes this is a physical difference in the two cards, the x4 or x8 refers to the number of lanes that exist for your data to travel down, this is explained quite well here;

PXI Express FAQ

Specifically this section;

What does x1, x4, and x16 mean?

With PCI Express, data is sent serially through pairs of transmit and receive connections called lanes, which give data the ability transfer at 250 MB/s per direction. Multiple lanes can be grouped together into x1 (“by-one”), x2, x4, x8, x12, x16, and x32 links to increase bandwidth to the slot. For example, a x16 slot would have bandwidth of 4 GB/s per direction (250 MB/s * 16).

Let me know if you have any more questions!

-Michael

[SteClaKUL]

Michael,

You stated:

The 7975R has an x4 PXI express connection, whereas the 7976R has an x8 connection, allowing for higher bandwidth to the host

The fact that you mention 'host' confuses me. The bandwidth to which you refer is that of the connection between FlexRIO and whatever the FlexRIO is connected to? In my case the FlexRIO is connected in a slot to a chassis (1085). Hence, in this case we are talking about the connection between FlexRIO and the switch in the backplane, correct?

[Michael_NIUK]

Hi, 

Yes, in the same way that the "host" would be the PC for a PCIe card, in this case, the "host" for a PXIe card is the controller and backplane.

-Michael