PXI 6608 80 MHz timebase

I have a PXI system with a 6608 timer device in slot 2 and a 5122 digitizer in slot 3. I know that the 6608 has an internal 80 MHz timebase, and I would like to use this timebase as a clock source for the 5122 using LabVIEW. I would prefer to route the timebase internally through the PXI backplane or a RTSI line, but would accept routing the timebase to something like PFI 0 and wiring it externally to the digitizer CLK IN. I have not been able to learn how to route the timer's 80 MHz timebase to another line that the digitizer can use for a clock source, and I have not learned how to use any digitizer external clock source but CLK IN and PXI Star. Any help would be appreciated in learning any of these things.

Please see this post.
Regards,
Natasa

Similar Messages

6608 80 MHz timebase

I have a PXI system with a 6608 timer device in slot 2 and a 5122
digitizer in slot 3. I know that the 6608 has an internal 80 MHz
timebase, and I would like to use this timebase as a clock source for
the 5122 using LabVIEW. I would prefer to route the timebase
internally through the PXI backplane or a RTSI line, but would accept
routing the timebase to something like PFI 0 and wiring it externally
to the digitizer CLK IN. I have not been able to learn how to route
the timer's 80 MHz timebase to another line that the digitizer can use
for a clock source, and I have not learned how to use any digitizer
external clock source but CLK IN and PXI Star. Any help would be
appreciated in learning any of these things.
This has also been posted to the LabVIEW board, I'm posting here to cover my bases.

Hi Tim,
The 5122 digitizer can be synchronized with external sample clock only if this clock is routed on the CLK IN (front panel SMB connector) or the PXI_Star_Trigger of the card. In your scenario, it would be easiest to export the 80MHz timebase from the 6608 to the PXI_Star_Trigger line and then specify that the clock source for the 5122 is the PXI_Star_Trigger. Use the Daqmx_Connect_Terminals.vi to export the 80MHz timebase to the PXI_Star_Trigger line on the 5122. On the digitizer side, you will have to use a property node in order to specify the source clock. Please see the jpg attached below.
I hope this helps.
Regards,
Natasa
Attachments:
export_signal.JPG ‏11 KB

How Can I Driving the PXI Backplane Clock with a PXI-6608?

How Can I Driving the PXI Backplane Clock with a PXI-6608?
Is the PXI Backplane Clock the timebase of the PXI Trigger BUS?
How Can I use a PXI-6608 as the timebase of the PXI Trigger BUS?
Thanks!

Hi,
The 6608 must be in slot 2 of the chassis. Once you make a call to the DAQ driver, the OCXO on the 6608 will be routed to the PXI_Clk 10 line.
More information on the backplane and routing clock signals can be found in these Knowledge Bases:
http://digital.ni.com/public.nsf/websearch/5EC370419A5ECA7A86256CFC0061C528?OpenDocument
http://digital.ni.com/public.nsf/websearch/D5B8D4D3B67DF1E086256BF8007BBF93?OpenDocument
I hope this helps. Have a Great Day!
George

Can we lock 80 MHz timebase to PXI_CLK10 on PXI-6220 M Series DAQ?

I am using PXI-6220 to measure Frequency/Period of 32768 Hz clock signal, accuracy is very important. I have provided signal to measure on Gate input of Ctr 0 (PFI 9). I am using 80 Mhz Timebase. I want to Lock PLL to PXI back plane 10 MHz reference (PXI_CLK10) which in turn is locked onto the 10 MHz reference via PXI-5600 on Slot 2 (External 10 Mhz standard is connected). so far I don't see a way to lock PLL to PXI_CLK10. Is that possible at all? see the image attached to this message.
Attachments:
M Series DAQ Question.png ‏62 KB

Hello Abhatti,
Based on the diagram that you have attached, the M-Series card can PLL to a higher accuracy clock such as the PXI Clock_10. The way to configure this change using the DAQmx driver is route the signals using the DAQmx Timing RefClk.Src Timing property node. Once you place down this property node, and specify the RefClk.Src attribute, you select the PXI-Clk10 as your reference clock source. This will discipline the 80 MHz Timebase of the DAQ card to the 10 MHz reference clock of the PXI chassis. Which chassis are you using? Also, how have you PLL'ed the 10 MHz backplane clock to the PXI-5600 Downconverter?
Michael L.
Applications Engineer
National Instruments

PXI-6608 specifications

Hi,
I have a question about the performance verification of the PXI 6608.
This is what I was able to perceive from the manual.
We have two modules:
CTR0: referenced to an external clock that has a minimum uncertainty of 0.75 ppb and generates a 400 s pulse to CRT1.
CTR1: is referenced to the internal 10 MHz OCXO and counts the number of cycles in that 400 s window: 400 * 10 MHz=4*10^9 . Any result different from this means an error.
Now to my understanding the performance verification is comparing the 10 MHz OCXO with the external clock. So by looking at the manual we have a uncertainty of 75ppb when the 10 MHz OCXO is on the slot 2: 0.75ppb * 10 MHz = +/- 0.75 Hz. BUT the performance verification assumes a tolerance of 0.1 Hz (10,000,000.1 < Hz < 9,999,999.9 Hz)
The calibration execute has the same approach as the performance verification,
Why does the PXI 6608 have a tolerance different from the manual?
Are we not testing the 10 MHz OCXO?

Hello,
In order to set the counter source to the timebase, you can use the the get/set/reset CI_CtrTimebaseSrc in order to set this in CVI. Please consult the DAQmx C reference Help for more information. Here are the functions if you can't find it in the help.
int32 __CFUNC DAQmxGetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[], char *data, uInt32 bufferSize);
int32 __CFUNC DAQmxSetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[], const char *data);
int32 __CFUNC DAQmxResetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[]);
As for performing a loopback test to test its accuracy, this isn't the best way to do this because the source is creating a signal with relatively the same accuracy as you are reading in back on the same device. Knowing that this signal is accurate down to .7ppm, we need to apply a source for the counter that is much more accurate than this. First way to do this is to change the timebase source to the 10MHz clock like I mentioned above. The other way is to place the PXI-6608 in slot 2 so that it overwrites the 10MHz clock on the backplane. This 10MHz clock is used with PLLing the 80MHz clock that is normally used in counter tasks. Which slot do you have the PXI-6608 in? Could it be placed in this slot?
Jim St
National Instruments
RF Product Support Engineer

PXI 6608 Measure Frequency 1Hz with accuracy 1ppm

I need to measure a frequency of 1 Hz with accuracy less than 1 ppm
icant do it with a PXI 6608 its normal ?
1 Hz is measured 1,000007 Hz by a PXI 6608
in this case, the error is 7ppm but i need less than 1ppm, i should measure 1,0000007 to have 0,7 ppm
please help its so urgent !!!!!!!!!

Hello,
In order to set the counter source to the timebase, you can use the the get/set/reset CI_CtrTimebaseSrc in order to set this in CVI. Please consult the DAQmx C reference Help for more information. Here are the functions if you can't find it in the help.
int32 __CFUNC DAQmxGetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[], char *data, uInt32 bufferSize);
int32 __CFUNC DAQmxSetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[], const char *data);
int32 __CFUNC DAQmxResetCICtrTimebaseSrc(TaskHandle taskHandle,
const char channel[]);
As for performing a loopback test to test its accuracy, this isn't the best way to do this because the source is creating a signal with relatively the same accuracy as you are reading in back on the same device. Knowing that this signal is accurate down to .7ppm, we need to apply a source for the counter that is much more accurate than this. First way to do this is to change the timebase source to the 10MHz clock like I mentioned above. The other way is to place the PXI-6608 in slot 2 so that it overwrites the 10MHz clock on the backplane. This 10MHz clock is used with PLLing the 80MHz clock that is normally used in counter tasks. Which slot do you have the PXI-6608 in? Could it be placed in this slot?
Jim St
National Instruments
RF Product Support Engineer

Performance verification PXI 6608

Hi,
I have a question about the performance verification of the PXI 6608.
This is what I was able to perceive from the manual.
We have two modules:
CTR0: referenced to an external clock that has a minimum uncertainty of 0.75 ppb and generates a 400 s pulse to CRT1.
CTR1: is referenced to the internal 10 MHz OCXO and counts the number of cycles in that 400 s window: 400 * 10 MHz=4*10^9 . Any result different from this means an error.
Now to my understanding the performance verification is comparing the 10 MHz OCXO with the external clock. So by looking at the manual we have a uncertainty of 75ppb when the 10 MHz OCXO is on the slot 2: 0.75ppb * 10 MHz = +/- 0.75 Hz. BUT the performance verification assumes a tolerance of 0.1 Hz (10,000,000.1 < Hz < 9,999,999.9 Hz)
The calibration execute has the same approach as the performance verification,
Why does the PXI 6608 have a tolerance different from the manual?
Are we not testing the 10 MHz OCXO?

Hi,
Thanks for your suggestion but my Qauestion is lillte bit different.
1) We have Equipment master in PM module.
2) Calibration scenario already mapped in PM with maintainance oreder with "14" inpsection type.
3) This is related to performance verification which is different from Calibration scenario.
4) i dont understand that what we have to do in QA05?
5) I want another inspection lot for "Performance verification" except "14".
6) We have defined frequency with test paramater. e.g. HPLC have PV frequency 3 month, 6 month & 12 month with different test parameter.
7) now i want that at each time point, i required auto generation of inpsetcion lot with defiened inspection plan in QA32. After testing will be completed, we will give UD and declare as this Equipment is Qaulified.
It is different from Calibration scenario.
Calibration actvity done by PM member but perfomance activity monitor by QA (QM) person.
Pls help me to design this scenario.
Thanks & Regards,
Ms. Kruti Shah

PXI-6608: Typical accuracy & stability for a 10 Hertz pulse-train output ?

I need to generate a very accurate and stable
10 Hertz continuous pulse-train for a test system.
What typical frequency accuracy & stability
can expect to achieve from the PXI-6608 for
a generated 10 Hertz continuous pulse-train.
I have read the specs ... just want to make
certain I am interpreting them correctly.
Thanks!

Hello there!
Though this was long time ago already I need confirmation on the same kind of calculations.
(However, in my case, I am measuring frequency, not reading, also with the 6608)
I thought the stability of 6608 OCXO was 75ppb per year (or 45ppb as stated in the OCXO notes). So therefore 11.25ppb/day. Not 0.45ppb/day.
In any case, if the stability of the OCXO is 75ppb :
- Stability on the 10Mhz clock: 10,000,000*75/1,000,000,000 = 0.75Hz
The question is, if you measure a 10Hz signal with this device, will you have a 0.75Hz accuracy? Or would you have the accuracy of the clock that you use to MEASURE (using a 100Khz timebase):
- Stability on time base: 100,000*75/100,000,0000 = 0.0075Hz
So apart from my measurement error (according to http://zone.ni.com/devzone/cda/tut/p/id/3619) I have to add up this error like this:
TOTAL ERROR = MEASUREMENT ERROR + CLOCK ERROR = X + 0.0075hZ
Being XX the calculated error made by the frequency estimation algorithm.

How to reset the Terminal Count indicator on the PXI-6608

Dear Community,
Is there any way to reset the terminal count indicator on the PXI-6608? When I Use Get Attribute.vi I get the correct value the first time, but unfortunately (unlike DAQmx) reading the value doesn't reset it...
I'd like to keep track of how many times it has rolled over. And I don't want to use another counter to do that because I'd like to keep them free for other things.
Thanks!
Cas
Solved!
Go to Solution.

Traditional daq does not have a means to reset the terminal count indicator, as far as I know. One thing you might be able to do is change the "output mode" to "toggle" and then read the "output state" to determine rollovers by determining when the output state has changed during your application.
I hope this helps!
gus....

Auto switch to BNC ref-in to replace backplane 10MHz if detected clock signal there with PXI-6608 on Slot2

Hi,
I m using chassis PXI-1045. The priority of backplane frequency is Slot 2 => Ref-In => Origin Backplane 10MHz.
But I wanted the backplane frequency to be in the priority order of Ref-In => Slot 2 => Origin Backplane 10MHz.
So,
It is possible to change the priority ? maybe by edit the config file somewhere else ?
If the priority is uneditable, is there any function/VI to disable the Slot 2 PXI-6608 from replace the backplane 10MHz ? (from LabVIEW interface) Let say disable the device without access to MAX ?
Thanks a loottt
BR,
engwei

Hi Eng Wei,
I've checked with R&D, and the priority of the clock selection is embedded in the firmware on the backplane. So unfortunately it is not possible to change the priority via software.
As far as the DAQmx functions are concerned, I did a check but was also not able to find any function that can disable the NI 6608 clock from being used to override the PXI backplane clock.
Is it a must that the NI 6608 be placed in slot 2, if it is not used to drive the backplane?
Best regards,
Victor
NI ASEAN

How To output the PXI-6608 OCXO to PXI_CLK10_IN

Hi!
I am trying to make high accuracy measurements with the PXI-6608.
I am using a 3rd party PXI backplane which has no StarTrigger slot that would override the PXI_CLK10 automatically with the PXI-6608 OCXO output PXI_CLK10_IN.
It appears that the PXI-6608's OCXO has no direct link to the time source of the counters but that instead the time source can "only" be PLL-synced to PXI_CLK10 signal of the backplane. Is this correct?
I tried to measure the high accuracy OCXO output on PXI_CLK10_IN but got nothing. What needs to have the PXI-6608 output its OCXO clock to PXI_CLK10_IN?
ThanXs for your help, Hezapeter

By connecting the OCXO to the PXI_CLK10_IN, you are overriding the PXI clock to make a more accurate reference clock. So anything that is using the PXI clock at a reference will become more accurate. I believe you have to set the source reference clock for the DAQmx tasks to the PXI clock in order to get this benefit.
But here's how you connect the OCXO to the PXI clock.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Attachments:
Connect Clock.png ‏9 KB

Strange number from pxi 6608

We are using the PXI 6608 card with a six channel system
involving counters. When we run the program we get a very large count,
somewhere around 40million, and it the same number every time. The problem is
that there is no way that can be a real count. We do get other counts that seem
to be actual data but every couple of cycles this large number occurs .Our
counters our connected to a kill switch, programmed in LabVIEW that will cut
the power to the counters if they reach the maximum number of counts we have
set. We know the kill switch is working because we have measured counts that
cut the power. However, when this large number comes up nothing happens and the
counters remain on and our limit is set far below 40million. Has anyone seen
this or other instances like it?
Thanks

Hi,
At the moment I am not sure why your problem is occuring but am happy to look into the matter for you when I have a bit more information.
What version of LabVIEW are you using?
How is the PXI system set up? For example are you connecting remotely from a host PC using LabVIEW realtime or are you booting the system into windows?
Would you be able to provide an example VI and any project files that demonstrate the problem?
Tom Clark
Message Edited by ThomasC on 08-06-2008 11:01 AM
Applications Engineer
National Instruments UK & Ireland

PCI-6281 How to use80 mHZ timebase for A/d and D/A sample clocks

Does anyone know how to use the 80 mHZ internal clock as the timebase for my A/D and D/A sample clocks rather than the default 20 mHZ timebase?
I am using straight NI-DAQmx version 8.3 with C code. No Lab View, no Measurement Studio.
I have an application which uses the D/A to generate a sequence that is collected by the A/D. The D/A is clocked out at an integral multiple of the A/D clock. In order to maintain this integral relationship I can only use a limited set of Sample Clock Timebase Divisor pairs (as returned by DAQmxGetSampClkTimebaseDiv). This means that am further from my desired base frequency than normal. For example, using the degault 20 mHZ timebase, if I want a 2000 hz center fequency, the closest I can get is 2003.205 hz.
I cannot find anyway to use the 80 mHZ internal clock as the timebase for my A/D and D/A sample clocks. If I could, it would be possible to get closer to my desired center frequency.

Post is responded to in the multifunction DAQ forumn.
PCI-6281 How to use80 mHZ timebase for A/d and D/A sample clocks
Have a good one.
Michael D
Applications Engineering
National Instruments

PXI 8156 166 Mhz CPU upgrade?

I am looking at installing Win 2000 onto a PXI 8156 controller with a 166 Mhz CPU, so is there a CPU grade path from NI for this controller? Or will it just take a 233 Mhz Pentium or even a 333 AMD, or will the mother board need to be changed�? Has any one swapped the CPU successfully?

Hello,
We have newer controllers that ship with Windows 2000. The new family of controllers is NI 8171, and it comprises three (3) different controllers: PXI-8176, PXI-8175 and PXI-8174.
Each controller has different specifications. The processor speed ranges between 566MHz and 1.26GHz, and you have a minimum of 20Gb hard-drive. We fully support these controllers under Windows 2000, among other Operating Systems. If you are interested in using Windows 2000 for your PXI system, one of these controllers would be the best upgrade option.
You could try to upgrade the p
rocessor of your PXI-8156 controller from 166MHz to a higher frequency. However, because we do not support upgrading the processors or motherboards of our boards, we have not made any tests on this so there is not any information about it.
In the Applications Engineering department, we have installed Windows 2000 in a PXI-8156B controller, which has a 233MHz Processor. See KnowledgeBase 261E93YQ : How Do I Upgrade My PXI Controller to Windows 2000? for more information.
Hope this helps,
Claudia Lorente
Applications Engineer
National Instruments
http://www.ni.com/ask

Doing something the DAQmx way that doesn't fit? (Triggered counter on PXI 6608)

Hi,
I want to create a counter with my PXI6608 that is triggered with an external input, then counts up. I then want to be able to read the count in LabVIEW and hence determine the time since the trigger. I have achieved this before with old-style code, but it is not clear how to do it the DAQmx way. In particular, I can't create a task because what I'm looking to do doesn't seem to fit in with any of the pre-envisaged DAQmx task templates.
Can anyone help? I'm assuming there's some way to create an 'empty' DAQmx task so I can fill in the details with property nodes?
Cheers
Lee
Solved!
Go to Solution.

You'll want to make an edge count task and set the source to be one of the internal timebases using a DAQmx property node (set it before starting the task):
The trigging functionality you're looking for is called an "arm start trigger" in DAQmx. It's configured through a property node (also before starting the task):
I'm not sure what you're getting at with regards to the "empty" DAQmx Task. Typically you'll use the standard API to set typical properties and the property nodes for more advanced functionality so you'll end up with a combination of the two. In many cases you could replace the DAQmx API with property nodes (for a fun example of this, open up the DAQmx Timing VI), but odds are you might be forgetting something important so I would always suggest using the VIs and then tacking on property nodes for additional functionality when necessary.
If you're using LV 2012, this example should get you started (or if not, the picture still shows you what the task would look like).
Best Regards,
John Passiak

PXI 6608 80 MHz timebase

Similar Messages

Maybe you are looking for