Using USB-6361 To Convert Sine to TLL

[Claxton]

I’ve recently acquired a USB-6361 with BNC connections. I’ve read many posts on the Community and looked through the documentation, but I’m confused on how to configure the DAQ for my application. What I want is this:

1. Read AC voltage (~ 300 kHz) at dev1/ai0
2. Convert to digital pulse train (TLL) with the same frequency
3. Route TLL through one of the BNC PFI ports to another device

I’ve been playing around with LABVIEW and DAQ assistant seems to be the easiest way to read the analog signal. But I can’t seem to convert this to a TLL using a Digital Output task. In addition, it’s still not clear to me how to route this signal through a PFI port?

I have some experience in LABVIEW but am very new to DAQmx, so any advice (however basic) would be greatly appreciated!

[Tepig]

I think implementing external circuit which has a comparator is the best way.

Sine Wave To TTL Converter

I also think we can develop the application on LabVIEW + DAQmx but, it should have phase delay.

I don't recommend.

[Claxton]

Hi Emboar,

Thanks for the advice. I’ve tried a comparator circuit but I could not get it to work.

I thought the DAQ board has the hardware to do this as well, since this is analog-to-digital conversion? I’m still interested in using a LabVIEW program. A phase difference between the sine & output is okay for my application. Do you think this would be relatively easy to achieve?

Best,

Clayton

[SteveD123]

Why not just use a 74LS14 Schmitt trigger?

[Tepig]

As Steve mentioned, using IC is more convenient.

But if you really want to achieve the feature in LabVIEW, just compare AI with threshold.

[SteveD123]

Thinking about your problem a bit more:

Are you sure you mean TTL, or do you mean +5V High logic? Actual original TTL levels are confusing.

Are you sure you have a simple sine-wave? No spikes or runt-pulses? These can seriously upset things if you get pulses where you do not expect them, and they can be very hard to find unless you set your oscilloscope up to specifically look for them. Most modern Tektronix instruments will have special modes for this.

Have a look at the CMOS 40106, this is more tolerant of different levels than TTL.

[Claxton]

Hi Emboar,

Thank you for the example program. I’m having a couple problems implementing my version however (see attached).

One thing I did not mention before is that I want this program to run continuously (thus my while loop). However, I run into a couple sampling problems. Namely, I get an error saying that the application cannot keep up with the hardware acquisition. I’m wondering if this is a problem with the software/bus itself, since I’m trying to read/output a 300 kHz signal.

Do you have any suggestions for this?

Best,

Clayton

[Tepig]

You should adopt "Producer/Consumer Design Pattern".