Acquire N Scans doesn't work

[Giulia]

Acquire N Scans VI (it is an example VI) does't work to collect noise ( no input connected)

[shoneill]

I'm not quite sure what you mean. If you mean that the A/D card delivers no values when there's nothing connected, then I'd contact whoever sells the card. If you mean that the LabVIEW function doesn't work without wiring channels to it, then I agree it doesn't work.

You need to wire a channel to the function to let it know from which hardware channel of your A/d board to read. If there's nothing physically connected to the card, you'll measure noise.

Hope this helps

Shane

[Giulia]

The problem is: I don't measure noise, but I measured it before. So, the problem is not the device (it is a PXI-4472) but it is in Labview. Nothing has been modified. Yesterday it worked, today it doesn't work.
Look at the VIs: they are extremely simple. Cont Daq and Acquire N Scans are the same as those in the Example Fider. Only ACQ&Wite has been little modified. They acquire only if signal is more than 0.465 V pk-pk.

[shoneill]

I only have the evaluation version of LV 7 on my computer, and I don't have any DAQ installed for it. Therefore, I can't test the program. I have seen, however, that you send "0" to the parameter for "number of scans" for the AI Start function. Is this correct for continuous scans, or should this not be "-1". This should have absolutely nothing to do with 0.465V as a threshold though..... sorry if I can't help more, but I don't have the VIs on my computer, and therefore don't have any help for them either.

Some functions also default to device 2 instead of device 1. Is this intentional?

Shane.

[Giulia]

The question is: have you ever heard that some DAQ VI don't work if input signal is too low? It seems quite strange.

[shoneill]

The only thing I can imagine is if the input range is set too high (The gain too low) so that the resolution is too low to detect any better then +- 0.465V. +-0.465 V is a HUGE threshold if this has anything to do with resolution! Are you sure it's Volt, and not Millivolt?

Shane.