How to synchronize PCI4474 and PCI6601

[yuanjia]

I am a new user of DAQmx. I use 4474 to acquire virbration singal and use 6601 to acquire tacho signal.I heard that PCI 4474 and PCI 6601 can be synchronized by RTSI,but I really don't know how to  do it in details. I used the example in labview,but it can't work . Because it is used for PXI. The settings of PXI and PCI are different. Is there anyone can give me some examples. Thank you!

[Jack_A.]

You can share the start trigger and the AI sample clock from the PCI-4472 with the PCI-6602.  The major difference between the PCI and PXI versions is that the PCI 4472 and 6602 are not able to share the SampleClockTimebase.  This is becasue it is exported only on RTSI 7, which is not accessible by the PCI-6602.

Here's a link to an example which shows how to manually export signals from a DSA device. 

Manually Exporting Timing Signals from a DSA Device

Once you've exported the signals to RTSI, you can import them on the PCI-6602 in a similar fashion.

Hope this helps.

-Jack

[MiamiVipul]

Hi yuanjia:

I'm a new user and just started using OAT toolkit with very-similar setup to your DAQ system. I have NI 4472 and NI 6601 and trying to get few examples running; I have difficulty in connecting these two cards and running the examples.

My system has two displacement sensors and an optical encoder. I need to run the "even-angle refenence signal processing" example since it will give very much I'm looking for.

Do you have any example code that I can try and understand the process of getting these two cards together? I would highly appreciate any help in this regard. I'm using Labview 7.1.

Thanks a lot.

Vipul

[preston_johnson]

There is an example in the Order Analysis Tools Example Library....  I have attached it here.  These show the use of a 4472 and a counter board in PXI.  The RTSI lines may be slightly different if you are in PCI.

[SH.Billy]

As Jack have said, you can share the start trigger and the AI sample clock from the PCI-4472 with the PCI-6602(6601), but the PCI 4472 and 6602(6601) are not able to share the SampleClockTimebase. So the synchronization is not strict for the PCI 4472 and 6602(6601), because both of the boards are using their onboard SampleClockTimebases, which are not synchronized. But since the frequency of the onboard SampleClockTimebases is so high (20MHz), we may consider the AI and the counter synchronized within a deviation if we synchronize their start triggers by RTSI. Here's an example which shows how to sync a PCI-4472 with a PCI-6602. For PCI-6601, it should be quite the same.

Message Edited by SH.Billy on 09-12-2006 10:21 PM

[MiamiVipul]

Billy:

Thank you for your valuable input. I was able to run your Log Data VI and I could see the correct RPM !!!! 

I was trying to use your code together with other OAT examples; especially, one that I received from NI technical support personal after modifying to accomodte PCI instead of PXI. I found that your modified version of oax_Sync DSA and TIO (DAQmx).vi (in your case ,it was named as oax_Sync DSA and TIO (PCI, DAQmx).vi ) and one I got from NI are quite different. I have attached the entire set of Labview files I got from NI. Since your one is correct, I wanted to use it instead of one I got from NI (oax_Sync DSA and TIO (DAQmx) 4472.vi). When I simply used your "oax_Sync DSA and TIO (PCI, DAQmx).vi" in place of "oax_Sync DSA and TIO (DAQmx) 4472.vi", I did not get any results.

What I'm not quite following is this synchronization thing. As I'm new to Labview, I could not completely understand how my 6601 and 4472 are synchrinized through VI's (well, I understand that why we need to synchronize). Would you please let me know what's wrong with what I got from NI directly? I would highly appreciate if you can make the one I got from NI to work.

Again, thanks a lot fro your valuable time.

Vipul.

[SH.Billy]

Hi Vipul,

Please try to replace the "Even Angle Reference Signal Processing (Digital Tacho, DAQmx) 4472m.vi" with my attachment.  And you also have to replace the "oax_Sync DSA and TIO (DAQmx) 4472.vi" with the "oax_Sync DSA and TIO (PCI, DAQmx).vi" manually. I can not do it for you because I do not know in which folder do you place the sub VIs. Make sure you have connected the 4472 with 6601 with a RSTI cable provided by NI as well as register it in the MAX. Make sure in the properties configuration of both 4472 and 6601 in the MAX, you have selected the same RSTI cable. Try again after finish this revision.

The revision I made to the "Even Angle Reference Signal Processing (Digital Tacho, DAQmx) 4472m.vi " is quite simple, just set the "synchronization type" input of the "OAT Build Digital Tacho Info.vi" to "by using reference clock". This would require the sub VI to use 20MHz as a sampleclocktimebase while calculating the digital tachometer signal.

The examples of OAT is prepared mainly for the PXI platform. In the PXI platform, there are many methods could be used for synchronization. In the OAT examples, to synchronize the AI and TIO, there are two different methods. For 447x, the sampleclocktimebase of AI is exported to the TIO. For 446x, the 20M timebase is connected to the AI as a RefClock. But for the PCI platform, both methods do not work, because the PCI slot and the RSTI do not support these routings. So we have to use a workaround here. The AI uses its own timebase while the TIO uses the 20MHz timebase. And then, use the AI start trigger to start the TIO. This method is not as accurate as the methods we use for PXI platform. But since the 20MHz time base is fast enough in most cases, we can just ignore the variance. Does it make sense for you? Hope this would help.

regards,

Billy

[MiamiVipul]

Hi Billy:

I could not open the VI as I'm using Labview 7.1. Will you please be able to post the same VI in 7.1.

Thanks a lot for the instructions. I think your VI will definitely help me to fix the problem.

Thanks a lot.

Vipul.

[SH.Billy]

Hi Vipul,

There is a LV8.0 folder in your ZIP file, so I thought you have upgraded to LV8.0. That's why I modified it with LV8.0. I have revised the VI with LV7.1 and tested it on my PCI platform with 4471&6602, it should be runnable, so please have a try. If there is any other problem, please feel free to let me know.  🙂

regards,

Billy