DAQ output mode

[Jaywai]

Hi, are there any documentations that talks about the difference between the different output modes with DAQmx? I see there is analog out, digital out and counter pulse but don't know their differences.

[ZYOng]

See C:\Users\Public\Documents\National Instruments\NI-DAQ\Documentation\NI-DAQmx Help >> Measurement Fundamentals >> Signal Types

[Jaywai]

I understand analog and digital signal in general but I am looking for actual description of them for the DAQmx. The main reason I want to know this is that I want to generate a TTL to trigger external devices. It seems that digital, analog or counter can produce a square pulse so I want to know what is the difference and what is the most efficient/common to generate trigger pulse.

[ZYOng]

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@Jaywai wrote:

I understand analog and digital signal in general but I am looking for actual description of them for the DAQmx. The main reason I want to know this is that I want to generate a TTL to trigger external devices. It seems that digital, analog or counter can produce a square pulse so I want to know what is the difference and what is the most efficient/common to generate trigger pulse.

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The main difference is in the sampling rate for the x-axis and amplitude for the y-axis. Taking the low-cost DAQ USB-6001 as an example, from the USB-6001 Specifications:

When using analog, you can specify any amplitude between +/- 10V and the smallest pulse is 200 uSec.

For digital, most NI DAQ use 5VTTL and digital task can access the counter for a higher frequency pulse.

[Jaywai]

Thanks, I have a better idea now. Are there any documentations that talk about these in more details?