synchronisation different signals in my VI,

[suksunh]

Hi,

          Could anyone please have a look at my VI? Basically, I'm taking signals in from 2 different PCI cards (E-series and M-series) as noted in my VI. Ultimately, I would like to synchronise all those signals together. Although I know that the signals in my VI are not synchronised, could anyone please check if all the signals in my VI are sampled at more or less the same time (with acceptible time offset between signals, say 1 ms offset, not 1 second offset)? I would be even more appreciated if anyone could suggest me how to effectively synchronise all these signals together.

          The signals I was extra worried was the top 2 signals from M-series card. Both of them are sampled at 100 Hz, one with 10 buffer size, the other with 2 buffer size. Are both of these signals more or less taken at the same time (In other words, are they more or less synchronised, although not precisely)? 

          Please find my attached VI with this message.

          Thank you very much in advance.

     Warm Regards,

           Suksun

[Stuart_R]

I can't run the code, as you've forgotten to include some subVIs. Looking at the code, you haven't implemented anything in order to achieve synchronisation such as triggering and sharing of sample clocks. If this is for PCI daq devices, you will need to use a RTSI cable in order to route these signals between the PCI devices.

Depending on why you need synchronisation, you could carry out post analysis and align the signals, but this will require a lot of coding to get the array manipulation correct. Take a look at the LV shipping examples for synchronisation (Help>>Find examples>> hardware input/output>>DAQmx examples>>Synchronisation).

[suksunh]

Hi S R,

        Thank you for your answer. Actually, I have seen some examples in the path you've given me. However, I found it very tricky to incorporate those steps into my VI. I don't know how to verify whether Ctr and AI from the same card and different cards are synchronised (after trying to follow some ideas from the examples).

         You mentioned about "array manipulation". As you might have seen in my code, there are different sizes of arrays (Ctr and AI). I'm not too sure if the synchronisation of those signals are badly affectly by this (of course, I didn't use any trigger or share any clock source among different signals, but if my understanding is right, there shouldn't have big delays of time between different signals).  

         For my code, sorry, I didn't expect anyone to run my code. However, as my llb code is in different place, if you remove signals from the bottom part (E series card), you should be able to run it and if you could suggest me the way to synchronise only those remain signals and the way to verify if signals are synchronised, I will be very much appreciated.

    Thanks a lot,

        Suksun

[Stuart_R]

I would still recommend looking at the example I mentioned. If you don't trigger and sync the clocks, there is no way to ensure synchronisation.