10 us pulse

[Ali84]

Hello everyone. I have a NI USB DAQ6501 which I'm trying to use to generate 10us width pulses. The frequency doesn't need to be too high (100 Hz would be enough) but the pulse cannot be any wider. So far, I have succeeded in generating a series of pulses, but unfortunately, a lot wider than I need. I 'm not sure if this DAQ is capable of such feat?

Also, I'd like to point out that the width of the pulses I generate is not the same, it keeps varying from pulse to pulse. Whiy would this be happening?

Thank you in advance for any help you can provide.

Ali

[BeCeGa]

Hello Ali, the problem you are having with the smaller size you can create and the difference in pulse width are both because you are using software timing for the output. This means that you send the pulse every time your while loop executes. Software timing in a Computer with Windows is limited to a minimum loop of 1 ms, that is why you can’t really shorten the pulse. Also as the difference between one write and the other is given by software it gives a larger jitter and that is why you don’t send the same with.

Here you need a Hardware Timed Digital Output (Correleted DIO) or a RT system (with your current card) you could use M Series Multifunctional Daq Cards, HighSpeed DIO, some S Series, the R Series or a CDAQ.

If you requiere to use a USB port the CDAQ is a great option.

What Devices Other Than M Series Can Perform Correlated Digital I/O?

Digital Input and Output Benchmarks for USB-625X and Compact DAQ

Can I Use Different Sample Clocks for Correlated DI and DO?

http://sine.ni.com/devzone/cda/epd/p/id/1566

M Series Frequently Asked Questions

The final option is need to use your card, you need a computer Running Real time. With this you could make deterministic programs (which will make jitter smaller) and  run up to 1us so you could instead of changing the card change the OS

Best Regards