Programmatically find if Chassis is using external 10 MHz (1085)

[Colonel1013]

Hi all,

Is there any way for me to remotely determine if my PXIe chassis (1085) has locked on to the external reference I feed into its 10 MHz IN connection?

The manual states this is done automatically, but I'd like to make sure it is.

"You also can drive a 10 MHz clock on the 10 MHz REF IN connector on the front panel of the chassis. When a 10 MHz clock is detected on this connector, the backplane automatically phase-locks the PXI_CLK10, PXIe_CLK100, and PXIe_SYNC100 signals to this external clock and distributes these signals to the slots. Refer to Appendix A, Specifications, for the specification information for an external clock provided on the 10 MHz REF IN connector on the front panel of the chassis."

I am using LabVIEW, and couldn't find any drivers or VIs to do this.

Thanks

[AndyCandy]

Hi Colonel1013

I don't believe there is a way to programmatically determine this, though you could theoretically scope the clock coming out of your external source, and the clock from you backplane after having been PLL'd to that source to verify.  You would likely still see some skew, however, but could watch the clocks over time for drift.  If they are the same clock, you would not see any drift.

[jonnycodesalot]

Colonel,

PXI Platform Services 15.0 will expose the ability to confirm the source of the 10Mhz Clock in MAX, in the right pane attributes for PXI Express chassis.  The update should be available for download sometime in early August. 

Programmatic access will not yet be available, but is a good suggestion.  I will put this in our backlog to be added in a future release.  I hope that the ability to confirm it in MAX will be a suitable workaround until then.

[cyphish]

Hi,

Apologies for digging up this old thread, but this is exactly what I need.

Do you know if programmatic access will be implemented in the next version?

If yes, when can we expect a release?

If no, will it ever be included?

Thanks.

[jonnycodesalot]

Do you need access to the attribute in C or LabVIEW?  Access in C should be available in the next few releases.  Access in LabVIEW is planned, but I have no information on dates.

[cyphish]

We use LabVIEW but I suppose we could make a DLL call and use the C-functionality, correct?

[jonnycodesalot]

Yes, that should work.

As of 15.0, the attribute is accessible via the NI System Configuration API, but this is not yet apparent because a header has not yet been made available to publish the necessary attribute IDs and enums.  That header will be included in an upcoming release, but I will provide the necessary information here so you do not need to wait.

You can access the property via the function NISysCfgGetResourceProperty, with the following attributes:

- resourceHandle - refers to the chassis for which you want the attribute.  Refer to the documentation linked above understand how to search the system's hardware and obtain this handle.

- propertyId - the number 184635392 for PXI Clock 10 Source

The returned value will be a signed 32-bit integer, which can be interpreted as an enum with the following values:

-1 = Unknown, or undetectable

0 = Internal Oscillator

1 = External Clock Input

2 = System Timing Module

I hope this helps.

[cyphish]

That looks very promising. Will dust off my C knowledge and give it a try 🙂

Thanks!

[dietricb]

How can I access this status? Since we now have 2018 and I can not find it in NI MAX!

[jonnycodesalot]

Click the chassis item in the left-hand pane.  The CLK10 source should show up in the right-hand side under the "Settings" tab as "PXI Clock 10 Source"