How do I use the PXI_clk10 backplane clock? It's not there!

[einarsto]

Hi, folks!

This might seem a trivial question, but I'm completely at a loss here. I have made an RT-project in LV8 which (among other things) samples data continuously from two cards located in a PXI-system. All 32 (16+16) differential channels are used and one task for each card is configured in MAX. Since signal phase is an issue, I need to synchronize both tasks accurately. The lv8 code examples have a couple of VIs that should have been directly applicable to my situation, and I have studied them (and lots of others) in detail.

 I have attached one example below that seemed to be spot on, and it makes use of the external PXI_Clk10 clock located in the pxi backplane. Here the confusion starts. When you attach a constant to the "source" input of the "sample clock" VI you get a drop-down list of possible sources. In the example code, PXI_Clk10 is chosen in this list, but when I try to do the same I discover that this option is simply not present. Only internal timing sources (located on the cards) can be chosen. If I configure the timing of the tasks directly in MAX, the PXI_Clk10 is an available option, but this leads to a vague error message when I start the tasks saying roughly that "it might be that you did not specify a name for the external sample clock...".

I have tried everything. My PXI-settings in MAX, routing signals via PFI-pins (didn't work at all), etc etc.

What is going on? Also: when routing a signal through a pfi-port, does this necessitate connecting the pfi-connectors physically or is the signal routed internally through the backplane? It doesn't help that I use BNC-2110 connector blocks. How can I be sure that the connectors on these blocks actually correspond to the terminals on the cards? I can't find a wiring diagram anywhere on the web.

Some facts: PXI-1031 chassis with PXI-8184 controller (dual boot) and two cards PXI-6229 / PXI-6259. These cards are located in slot 3-4.

Regards, Einar

[Jimmie_A.]

Hello Einar!

Seems like everything is in order and works like it should based on the test I asked you to do using on of the shipping examples. Just use the example VI and then modify it so it fits your needs!

[Lila K]

So what was the solution?  I am having the same difficulty - trying to use the shipped examples for synchronization of multiple devices, and I can only select internal timing sources for the constant connected to the RefClk.Src property.

I'm using a PXI-1044 Chassis with a PXI-8196 controller, 2 PXI-4462's (in slots 2-3) and 6 PXI-4461's (in slots 4-9)

Thanks!

-Lila

[VdG]

Hello,

i've the same problem...Does the PXI chassis generate this clock by itself or does it need a PXI controler ?

PXI-1033 chassis
6143 & 6133 S series
LabVIEW 8.2.1

[EBL]

All PXI chassis produce PXI_CLK10 on the backplane (from an on-board 10 MHz oscillator), and most of them can also receive a 10 MHz clock from Slot 2 and broadcast that on the backplane. Some models can receive 10 MHz from a BNC connector on the back. Similarly, both 10 MHz and 100 MHz clocks are always available on PXI Express chassis.

Unfortunately, the 6143 and 6133 have no provision to connect to PXI_CLK10. This is likely because the master clock on those boards is 20 MHz, and there may not have been board space or room in the cost budget for a PLL to lock it to 10 MHz. Many other PXI products can use PXI_CLK10, such as the 6120. There is a list of products which use CLK10 and other PXI features here:

https://www.ni.com/en/support/documentation/supplemental/17/how-do-national-instruments-pxi-boards-m...

I suspect this list is a little outdated; perhaps someone reading this knows where a more updated version is.

Hope this helps,
Ed

[VdG]

Yes, it helps ! very interesting link.

Thanks,

[jxjimmy]

I'm trying to find out how to get PXI_clk10 as well, it does not show up as one of the choice.

[steel_city]

Jimmy - I had the same problem and I haven't gotten a formal answer to this. I just typed in pxi_Clk10 into the dource constant. Alternatively, you can copy from the example VI. You may have already done this. It worked when I tried it.

[steel_city]

Jimmy - I had the same problem and I haven't gotten a formal answer to this. I just typed in pxi_Clk10 into the dource constant. Alternatively, you can copy from the example VI. You may have already done this. It worked when I tried it.

[mpelc]

Old thread, but I had the same problem recently. See

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000001DcYzSAK&l=en-US

Not sure why it's an "advanced terminal" though.