What is the maximum analog output frequency of USB-6259BNC?

[SSteve]

We need to generate four sine waves and control the phase between them. We're using a USB-6259BNC to collect data and I was hoping to use it for generating the output as well. So far in my testing, I can only get an output frequency of up to 1kHz. Anything higher and I get an error. (I'm controlling the 6259 with Igor through NI-DAQmx.)

Is 1kHz the practical limit for analog output or am I doing something wrong?

[Dennis_Knutson]

Since the specs say the max update rate is 2.86 MS/s, my guess is that you are doing something very wrong. My guess is that you are writing a single point at a time and of course, this is on-demand timing (or software timing) and your update rate is going to be highly variable and dependent on the pc, memory, os, etc.

[SSteve]

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Dennis Knutson wrote:
Since the specs say the max update rate is 2.86 MS/s, my guess is that you are doing something very wrong

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Ok, I guess my problem was that I had too many points in my wave. If I want to get a 26kHz wave, my output wave has to have 110 points or fewer in order to keep the update from exceeding 2.86MS/s. That makes sense now. Thanks.

[John_P1]

Hi SSteve,

Usually you explicitly specify the rate at which to generate then calculate the number of points to put in your waveform based on this.  Anyway, since it can often be confusing trying to figure out how many samples to write for certain frequencies etc, I would suggest looking into this example:

Generate Multiple Channels of Analog Output with Different Frequencies (take a look at the "Update Phase" version).

This also solves the problem if you want to generate a frequency that does not go into the sample clock evenly or if you have multiple channels of frequencies with no common multiple that is also an available sample clock rate.

Best Regards,

John

Message Edited by John P on 12-15-2009 11:53 AM