How to configure the two channels of NI5112 to sample with deferent sample rate?

[diaoxiumin]

Now I have some trouble with high speed digitizer NI5112:How to configure the two channels of NI5112 to sample with deferent sample rates?

[Josh H]

The NI 5112 will always use the same sampling clock for both channels, so you can't hardware configure two different sampling rates. You could, however, sample both channels at the larger sampling rate and decimate your data for the other channel. This would give you the same results as what you want, but would require some additional software programming on your part.

[diaoxiumin]

Hi,Josh H,
Thank you for your answer!I will try it.

[diaoxiumin]

Hi,Josh H,
I have two pulse signals with the frequency of 10Hz.The width of one of the pulse signal is 100ns,and that of the other is 200us.I am just interested in pulse information.Now I employ one NI5112 to sample the two signals at the same time with a sample rate of 100MHz.So I get about 40000 sample points with one triger.However,I find that NI5112 can't recieve 10 trigers in 1s.That is to say,some of the pulses are lost.
Can one NI5112 sample my two signals at the same time? Could you give me some suggestion? Thank you in advance.

[Josh H]

One thing to keep in mind when you are using the NI 5112 is that you can only trigger off of one signal. Therefore, if you want to see two different pulses, you will have to trigger off of one of the pulses and then take the data for both channels. In your case, you could trigger off of the 200us pulse and take enough data to see the entire pulse (~20k samples at 100MS/s). If you want to see more data than that and you're worried about missing triggers, just increase the number of samples that you want to acquire. Each channel on the 5112 has at least 16MSamples available on board.

[diaoxiumin]

Hi,Josh H,
Now I am using digitizer NI5102 and I get the sample points with the function niScope_Fetch.However,I can't get the triger time because the value of absoluteInitialX ,which is one of the elements of niScope_Fetch's last parameter,is always 0.When it comes to NI5112,all work well.NI5102 doesn't support this function,does it?Thank you!

[Josh H]

The feature that you are referring to is know as "timestamping" and it is not supported on the NI 5102. That is why you see 0 every time for the absoluteInitialX. This feature, of course, is supported on the NI 5112.