Timestamp PXI-5152 waveforms in GPS time
Hello,
I am trying to collect waveforms with a PXI-5152 and correlate them with other data which is collected in GPS time. I have a GPS receiver that can output a PPS pulse. The PPS pulse is the only signal that the two systems can share.
NI support recommended the following.
Split my PPS signal and send one copy into a spare channel on the 5152. Prior to my data acquisition, I would collect one waveform of the PPS pulse. The timestamp of this waveform would be used as my offset from the time counter on the 5152 to the GPS time (assuming I could figure out what second it was which I can)
The other PPS pulse would go to a 6682 time sync card. I was told the card could sync to the PPS and output a 10MHz clock to the 5152.
All measurements on the 5152 would then be converted to GPS time using the offset calculated earlier.
The problem I later found is that the 10MHz clock that is output by the 6682 is not disciplined by the PPS pulse. It is freerunning. Therefore, over time, there would be clock drift between the clock on the 5152 and my other data that is collected in GPS time. This is a problem as I must have 2.5usec accuracy on the time of the data collected on the 5152 card in order to be able to correlate it with the other data set.
Now the question is can this design be salvaged.? Is there a way to use the 6682? It would seem that the 6682 should be able to compute number out 10MHz clock cycles between each PPS pulse. For example if it output 10,000,010 clock cycles between PPS, then there would be a 1 micro second drift for that second. If I were able to read this error once per second then I could (in software) compute and update the error each second. This would allow me to esentially eliminate the clock drift over the long term.
If this is not possible then is there another card that can do something similar...I have been looking at the 6608 which may do something like this.
I appreciate any advice that is out there. Thanks!
Paul
Hi Paul,
You're right, the 6682 out of the box cannot discipline CLK10 to one of the supported Time References.
I think you have 2 high-level options. By leveraging a Trimble Thunderbolt's disciplined CLK10, you can create a system that samples synchronous to GPS. See this link for more information: http://zone.ni.com/devzone/cda/tut/p/id/6818
If you instead want to correlate your free-running 5152 samples to GPS, you're dead on with the approach although this would likely need to be supported with new features from NI-Sync. We currently support timestamping a signal directly which for CLK10 would amount to far too much data. I'd e-mail [email protected] to discuss the possibility of this further.
Thanks for the detailed e-mail
-Adam
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However, we need timestamp (UTC) the solar data at the beginning and end of each sample of 5 milliseconds, during all acquisition process, in order to have the UTC time information of recorded solar events. So, a time resolution of at least 1 ms is required.
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We know that GPS time synchronization with PXI-6608 can be used to precisely timestamp data acquisition, but we have to solve this problem with a lower cost. Also, we require a PCI interfacing instead of PXI.
Do we have to use a timer card? How do we use a timer, GPS and USB-6009 to timestamp data acquisition? Does the NI PCI-6602 solve the problem?
Obs:
The data acquisition software was developed in C++ Builder to run on a PC (Pentium III 2 GHz) under Windows XP environment. We used the NI-DAQmxBase driver to sample the signal from the NI USB-6009.
We are sure your expertise can help us on this matter.
Regards,I better explain my problem in the thread How to timestamp continuous analog data acquisition using USB-6009 and GPS timing board?
We are considering to use the PCI-1588 or a GPS timing board (low-profile slot too), but I´m not sure that the USB-6009 can be used to solve the problem.
How to syncronize the data acquisition and timestamps using USB-6009 and PCI-1588 with external GPS?
In other thread I would appreciate any suggestions for GPS timing board and PCI-1588 too.
Regards,
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Accurate timestamping 6608 counter intervals with gps irig-b
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cheers,
tom harrison
Solved!
Go to Solution.Hi, Tom Harrison.
There is a KnowledgeBase article that presents a solution to this exact issue: PXI-6608 Not Recognizing IRIG-B Signals For GPS Time
Things to check:
(1) Make sure your IRIG-B signal is the "DC Level" type.
(2) Make sure your IRIG-B signal is compatible with the PXI-6608.
(3) Make sure to attach the synchronization signal to the synchronization line of the real-time clock.
For more information on GPS-based synchronization with the 6008, read through this KnowledgeBase.
I hope you're having a great day!
Regards,
Sara Lewandroski
Applications Engineer | National Instruments
http://www.ni.com/support -
PXI gurus,
I am running a particularly noise sensitive experiment and it seems that the PXI-5152 itself is generating noise whenever the active LED turns from green/yellow to off (temporarily). I wanted to understand, if the "active" button is off, that means the PXI isn't triggering, but I have a laser constantly firing, so hypothetically it should always be triggering (10 Hz), but it seems that sometimes it stops for ~500 mS and then continues.
Is it possible that when the active button is on that it is generating some sort of transient noise? (noise width 10%-90% rise time is approximately 250-750 nS and the noise is around 150 mV when my baseline is 50 mV after amplifying my electrical signal 100X with a Tegam 4040B amplifier.) If so, is there a way I can mitigate this?Hello bravedonxiote,
The transition from Green/Amber to off in the active LED indicates that the module is not armed, triggered or acquiring a waveform.
Have you checked the Access LED to see if it is off as well?
Regards,
Luis C. -
How to access PXI 5152 from a Laptop via ethernet cable?
Hi, I have the following setup.
PXI 1002 chasis
PXI 8175 controller
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I have written a program that uses the counter timer for triggering an external circuit board and the scope for data acquisition. I need to run the vi on my laptop and get access to the PXI devices.
I have connected the Laptop to the PXI using a cross over LAN cable and configured manual IP addresses and identical subnet masks on both systems. If i run the Remote Device Access Server(RDA) on the PXI chasis, I can access the 6025E card and a portion of the 6602 card also. I can see them from MAX directly.But how can I access the scope, as the RDA server works only with DAQ devices.
What I want is a method to configure the PXI system as a remote device on my Laptop.so that I can see the PXI cards in NI MAX on my laptop.
I would like to see if I can do this without having to get a new express card.
Please help!! I am newbie with remote systems.
Thanks in advance!!Hi JJ,
Sorry for the delay. You are correct that using remote
front panels will still require the VI to run on your PXI system, and you will
not be able to do any configuration other than that allowed with the front
panel. If your controller is slow, is there a reason why the development can’t
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test? To help speed things up on your PXI system, you could create an exe on
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As far as the RT vs. Win 2000 – this can
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Hope this helps you out.
Message Edited by David L. on 06-10-2008 02:37 PM
David L.
Systems Engineering
National Instruments -
Hi am trying to save Data into a write to measurement file vi using a NI PXI 1042Q and DAQ NI PXI-6229 with a real time mode but it is not working but when i run it without uploading it into the PXI it save in to the file please find attached my vi
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PWMs.vi 130 KBother problem is that the channel DAQmx only works at real time mode not on stand alone vi using Labview 8.2 and Real time 8.2
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How to get PXI 5152 working in LabVIEW 7.0
Hi,..I recently purchased a PXI 5152 digitiser. The driver CD had NI Scope 3.4 which, when installed worked fine. But it also installed NI DAQ MX 8.5 (min. requirement) and removed my older version of DAQMx.. This new version DAQMx 8.5 does not support LV7.0. (My APE is LabVIEW 7.0.) So I can't get any DAQMx I/0 blocks from LabVIEW.
When I uninstalled DAQMx 8.5, NI Scope 3.4 also got removed. Then I rolled back to my old config of DAQ and Scope 2.5. But now my digitiser is not recognised.
Where can I get a 5152 digitiser driver(NI SCOPE) that works for LV7.0 also.(I was unable to find one from NI website. They all needed LV7.1 or later)
I am using a PXi system with PXI - 8175 controller.Hi,
Sorry I did not realize you had a PXI-5152 and like it was posted by one of my co-workers the PXI-5152 will only be supported on NI-Scope 3.2 or later. The NI-Scope 3.2 requires LabVIEW 7.1 or later. In this case you options are like Sam said upgrading LabVIEW or getting a new digitizer.
From the list you posted on the previous thread you should be looking at: LabVIEW 8.5 Compatibility Information. For your timing and your DAQ device we can check the driver in this website: NI-DAQ Driver Support: PCI/PXI Devices .
Now for the PXI-8175 we need to take a look at the minimum requirements for LabVIEW 8.5 and the best place to search for this data would be here: Release Notes.
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How do i change 2 row of array into waveform with delta time and time
Hello,
How do i change 2 row of array into waveform with delta time and time
so the waveform graph will display two waveform,
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Here is an example VI, that do what You asked for.
Both requests.
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Reset waveform chart relative time
Hi all
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Thanks in advance,
Regards
Shady
Solved!
Go to Solution.
Attachments:
block diagram.jpg 48 KB
Chart with DataTime Beginning from zero.vi 21 KBshadyman wrote:
Ben
First of all thanks a lot of your reply.
I just want you to clarify how can i replace this tunnel with a shift register ,where will this sr take the data from ,coz the "Get current date and time" is actually placed outside the loop ,also how can i replace this value with a case structure ,shall i put the "get date and time" in a loop or in a case structure ? coz i actually tried ways that looks like that but it didn't work .
I will appreciate that a lot if you showed me what you mean by a diagram. or on the actuall vi that i attached to the post.
Thanks in advance
Regards
Shady
I reserve that type of service to my paying customers.
Let me turn it around and welcome YOU to post an image of what you have tried and let us comment based on your efforts.
I'll get you started with two suugestions and a question.
1) You can right-click the input tunnel and select "replace with Shift Register".
2) If you watch your code in execution highlighting mode, you can see were the data comes from and goes to when.
Now for your question!
After watching the code run where would there have to be another "Get time" node have to be located to get a new value WHILE the loop is running?
Like I said post images of what you are attempting to do and let us offer advise based on that.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction -
Log GPS time, position, velocity
Hi,
I'm using the read gps time, position, velocity.vi and now I want to log this data in a text or spreadsheet file. Is there a simple way to do this? I tried with write to measurement file, but this only handles dynamic data and no string or time stamp.
Thanks
Solved!
Go to Solution.a much different take, note the string constant format to anything...
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test.vi 8 KB -
How to synchronize the system time/date of a PXI controller with a GPS or time server?
Using a PXI system with a NI-PXI 8196 controller and LabVIEW RTOS, I am searching for a solution to set or reset the on board timeclock of the controller trough a external signal like a GPS or a time server (ntp).
Do an easy way exist to do this?
Any response will be greatly appreciated.
Philippe D.Hello Philippe,
combining those examples should resolve your request:
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=DB0882E37369122DE034080020E74861&p_...
and
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=EE349DC00D8D5E08E0340003BA7CCD71&p_...
or
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E23356A4E034080020E74861&p_...
Hope this helps,
Regards Thomas Bl. -
Hi..
I am using NAVILI>CK GPS for our work related to Laser radar data
aquisition. Through the simple code attached, I can read the time stamp
in the way 12:23:45 (say UTC, hh:mm:ss). But I want to have the time
stamp as 12:23:45.7653 (see change in the ss stamp). How to generate
this?
Pls post your reply
Regards
SandyHello Sandy,
as I can see in your programming, you retrieve the timestamp
information from your GPS device via the serial port. Can you configure
the device to send the millisecond information you need?
Otherwise you would have to generate your own timestamp in LabVIEW.
Maybe you can use the VI "Tick count (ms).vi" out of the
time&dialog palette to get the ms information. This VI is reading
out an internal timer and displaying the result in milliseconds. You
could calculate an offset from a starting point of the measurement and
add the information to the timestamp you get from your device.
Generating a timestamp beyond the millisecond resolution is tricky on
windows systems, because 1ms is the smallest unit in software timing.
You would need a counter signal or some other kind of hardware you
could use to time your loop.
Ingo Schumacher
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240 bytes of overhead in PXI-5152
The manual for the PXI5152 states that for each recorded waveform the amount of memory required is the number of samples + 240 bytes rounded up to the nearest 128.
Does anyone know what is stoed in the 240 bytes? We are using the card to trigger 100's of thousands of small waveforms (<64 samples) per second and this large amount of overhead is haveing a huge impact on our overall performance.
I am wondering if there is anything that can be done to eliminate this overhead for applications where very small waveforms are needed.
Thanks for any feedback!
Paul
Solved!
Go to Solution.Hello Paul,
I have more information on the exact purpose and nature of the extra bytes per record fetched. First, this extra data is not the record metadata. This data is returned to the host computer asynchronously and is not stored in the board memory with the record.
Next, the actual amount of data stored in the record in excess of the actual samples is actually 400 bytes on the NI 5152 (This information was corrected in the September 2008 version of the NI PXI/PCI-5152 Specifications, page 15). These bytes are allocated to each record to allow for proper operation of the board. This is necessary to allow flushing of the datapath to retrieve all of the data and to protect the record from being overwritten.
Regards,
Dan King -
Synchroniz​e two waveforms with different time
Hi All,
Thank you again in advance for you help on this. I am trying to create a setup where a spectrum is generated over time (millisecond time range, this function works properly), and a maximum for a peak that I select (this also works correctly) plots over time (minute time scale). However, when I try to run this, the fast plot is operating at about 40 Hz, and I have a calculation to allow a resolution feature for the minute time graph (the fast experiment is averaged a given number of times to produce a spectrum which is then analyzed for the maximum peak, so for example, at 40 Hz, and a resolution of 0.5 seconds, it should need to average 20 spectra for each point), but in operation, the time does not work correctly. At 20 spectra averaged per point, I only get about one point per second, not 2. So, in an attempt to correct this, I cut the averages in half, and was able to get it to work at very nearly 2 spectra per second. However, the time is not exact when compared to an external clock, and I need to know then exact time. Thus, is there any way to have the minute time frame graph count time on its own, and just plot a Y value whenever it recieves one? I need to have it plot in real time, as is currently achieved in the attached vi. In th attached VI, I am working with the "chromatography mode" tab, the other tabs already work correctly. However, I am somewhat new at this, and my code is a bit messy, so I apologize for that in advance. Thank you,
<>< Eric
Attachments:
IMS Software v5.4.vi 158 KBHello Eric,
I see that you are creating a waveform using the Build Waveform VI and then wiring it to the outputs in the Chromatography Mode tab - namely 'Waveform Graph' and 'Waveform Graph 3'. Is the 'dt' value constant for every iteration of the while loop? If so, your output should have constant time spacing between plotted values in the waveform graph.
So, again I am not completely sure what you mean by the IMS not operating at the frequency you input :-(. Are you seeing the problem in 'Waveform Graph' or 'Waveform Graph 3' or both? An simple example VI would be great to describe your issue.
Vivek Nath
National Instruments
Applications Engineer
Machine Vision -
I would like to see the time in a waveform graph (real-time​)
i need the x-axis of the waveform graph to show real time (from the computer clock). I have made a program with all the example. He read and log data when the chosen time has elapsed. the program work's well...but i dont't know why the x-axis blink every time he draw a point
i can see two x-axis in the same time.
i give you a picture of one of a part of my program, i hope someone can help me
Attachments:
my_software.JPG 128 KBHi,
I tried to reproduce what you were getting by building a simple VI but I havent had much luck (I have attached the VI).
Could you post your code so that I can take a look at it?
Feroz P
National Instruments
Attachments:
Graph.vi 39 KB
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