2 different USB DAQ boards in parallel

[mikeporter]

Sorry blokk,

I'm working on my phone and missed the a couple significant details in your code. Yes, your last diagram should do what I was describing. The only change is that because you have an external trigger you don't need the sequence structure. Likewise two loops will work, but it doesn't give you any advantage.

Mike...

[Blokk]

I see. Actually I just modified the example code from the NI YouTube video. Yes, I guess the sequence frame not needed, I could use error wire to ensure the proper execution order of the two DAQmx Start functions. I think the two loops were only used in the video for demonstration purpose, in real application we could use a single while loop I guess...

[mikeporter]

The big point is that there is no proper execution order for the two starts because all the start does in this case is tell the box to start looking for a trigger. No acquisition takes place until the trigger occurs.

Having two loops complicates things in (at least) two ways: First you have two loops to stop. Second, it complicates combining the data from the two sources.

Mike...

[dsasorin]

Thank tou very much, blokk and mikeporter for your advices.

Now I understand the principle of hardware synchronisation, and I followed the advices.

The exemple from "Analog Input - Synchronization.vi" doesn't work for my USB cards.

I make the .vi with hardware synchronisation (with cables for digital input and digital output) recommended by blokk, modified from youtube video.

The program is working, but for the DAQ USB 6210 to work, it is necessary to change the PFI lines properly.

Master board: sample clock out PFI4  and trigger out PFI5.

Slave board: sample clock in PFI0 and trigger in PFI1.

So this version is working fine, with this aspect: It is necessary to fizically connect the two boards with cables (mine are not BNC type, just simple twisted cables)

For my task, those cables betweeen DAQ boards, bother me. Because, initially i wanted to have two boards totally independent, at aprox. 5 meters one another. More, i wanted to be wireleslly connected to my laptop.

So now I am looking for a pure software synchronisation without cables between boards.

I made a schematic, see in attachement (V1 and V2).

What parts do you recommend for it to work, in each case  ?

Thankyou once again.

[dsasorin]

Of course, V2  with USB cables is totally covered by NI USB 6210,

but i was thinking at other boards, smaller, with minimum 1 AI voltage and 1 DI.

In principle, I want small boards, wireless with the possibility to attach battery. (5 - 9 Vcc)

OEM ar very good because of the lack of plastic case.