PXI-8196 Clock is drifting

[KDitlefsen]

I have two identical PXI set-ups each consisting of a PXI-8196 RT Embedded Controller (LabVIEW RT 8.21) and two PXI-7833 RIO boards in a PXI-1031 chassis. The systems have been up and running for a long time without any problems. Now, without any application modifications or software updates, it appears as though both the controllers have a problem with the clock source (clock/PLL?). The system clock is drifting by approximately 6% (running too slow). When in the BIOS, the clock seems to be running fine, but not when running my application. There also appear to be some high frequency jitter on the clock. I have attempted to format the hard drive, reinstall OS, drivers and LV application, as well as erasing and re-downloading bit code to flash of the RIO boards. All without any success. When running a small test-vi with a "Get Date/Time in seconds" block, it is evident that the clock runs too slow.Not so much just after a reboot, but after about a minute the clock starts to drift.

Please, what could be the cause of this problem?

Thanks,

Ken

[bogathc1]

A firend of mine had this exact same problem on his equipment, sounds very similar problem to yours. If I were you, I would check the temperature of your device as it appears that the PLL is not very stable if the clock gets to hot. Perhaps you need to clean the heatsinks on the contorller to improve the cooling, or install a bigger fan. 

[Marco_Ge]

I have experienced a similar problem.

I have two pxi'8104 controllers, connected with a laptop.

the  rt application must record analog and digital measures on both rt stations and then transfers it to laptop application.

it happens that the internal clock of the two controllers starts to derive after some minutes I have rebooted the systems.

I am getting some better result using "tic counts" instead of timedate .

I do not think, in my case, that there is a cooling problem.

it is terrible not having a real time clock on a real time unit...

sigh!

[Andrew McL]

Hi All,

Thank you for contacting National Instruments. This does sound like quite a serious issue and I would recommend that anybody who has experienced this problem should contact their local National Instruments office. I am not saying that this is a Hardware fault but it would be worth contacting your local office so that an Applications Engineer can eliminate this from the list of possibilities.

Most other cases that I have found have been related to customer's code so again, it would be worth discussing with an Applications Engineer so that we can help eliminate this as well.

I have included the UK office details below for UK based customers.

National Instruments UK & Ireland
Measurement House
Newbury Business Park
London Road
Newbury
Berkshire
RG14 2PS

Phone
01635 572414 UK

I shall continue to monitor this thread so please post back any additional details.

If you decide to contact the office (which I strongly recommend) it would be worth having the following available:

1. A list of all the hardware - ours and third party

2. A list of all drivers and versions

3. The code you are running

4. A description of how you are measuring this clock drift.

I hope this helps and that you manage to resolve this issues quickly.

Many thanks,