09-08-2005 09:57 AM
09-08-2005 11:37 AM
09-08-2005 11:48 AM
09-08-2005 12:16 PM
Hello JTed:
Yes, some of our boards do acquire data simultaneously... Our S-series boards allow you to do this. Our M-series and E-series boards have one analog to digital converter(ADC) which each channel is multiplexed to, allowing inputs to be taken only in sequence though the delay is small. The S-series boards have a dedicated ADC for each channel allowing for measurements to be take simultaneously.
I hope this clarifies the issue for you.
Regards,
Matt Sweetland
NI Applications Engineer
09-08-2005 12:51 PM
09-08-2005 02:04 PM
Theo:
I think what you should attempt doing is grab data from one channel for debug purposes. From this channel use an indicator to display your data as it is grabbed from the buffer; is your data displayed as a 4 column array then? Diagnose the problem piece by piece to better understand whether it is either software or hardware related.
Are you using an example vi? If so can you reply with the exact name of the vi? Even better, can you attach a copy of your vi so I can take a look at it?
Thanks,
Matt
09-08-2005 03:22 PM
Hi matt,
Cheers for responding so quickly. Right, I'm away from the rig right now, but I think I can answer your questions from memory...
The same problem occurs when I use either the vi that I wrote, and any of the example vi's that work for this purpose, like the Acquire N scans ExtChanClck.vi and so on. I forget which exact one I'm thinking of, probably the above one, but it has a display that shows the output from the AI read on the front panel as a column vector, which you can toggle to show the various columns. Even with this example vi, scanning only one (and any one of the four) channel(s), I still get exact duplication of the single channel, four times over. So you can toggle through four identical vectors in the front panel display. I even took the vi that i wrote and pared it down to just the bare elements and "removed as much software" as I could, so it contained just the clock config, trigger config and ai read vi's, and it still gave the same problem. I can post the vi for you at a later date, but given all the above I just can't help thinking it's a deeper problem. As a matter of fact, I eventually removed and completely reinstalled the Labview software, DAQ board and DAQ software out of sheer frustration, and still I see this problem. I've checked the shaft encoder signal with a scope, and at any given engine speed the frequency of the pulse is perferctly aligned with the rotational frequency, so I'm pretty sure it's triggering ok. I'm beginning to run out of options!
Thanks
Theo