Measuring Period <392ns (minimum period measurement capability)

[ADI_Tony]

I am trying to measure a period less than 392ns and I get the error :

Error -200141 occurred at DAQmx Wait Until Don.vi:3580001

Possible reason(s):

Data was overwritten before it could be read by the system.

If Data Transfer Mechanism is Interrupts, try using DMA or USB Bulk.  Otherwise, divide the input signal before taking measurement.

Task Name: _unnamedTask<E85>

 I have attached a screenshot of my VI

[JayJayHella]

Hi ADI_Tony,

What hardware are you currently using to take this measurement? Depending on the hardware you are using this may be the issue. 

[ADI_Tony]

I am using the PXI-6289.  It has an 80MHz counter which should still be able to "count" measure a period this fast. 

[JayJayHella]

Hi ADI_Tony,

What do you have your Number of Samples control set to? According to the specification sheet for the PXI-6289, the FIFO for the Counter is only 2 samples.

NI 6289

http://www.ni.com/pdf/manuals/375222b.pdf

If your number of samples, was greater than 2 it would make sense that you received the buffer overflow. Have you looked at the "Counter-Read Pulse Width and Frequency (Continous)" example in the NI Example Finder. Are you able to run this code without getting an error? 

So, if there are more 

[ADI_Tony]

I have been taking 500 samples.  For slower frequencies there is not problem.  The only time I have an issue is trying to measure a period <392ns.  Greater than 392ns works no problem

[JayJayHella · Accepted solution]

Hi ADI_Tony, 

From the screenshot in your original post, it looks like you are using only 1 counter, which is fine for low frequencies. Have you tried using a two counter method that works better for high frequency measurements? An example for which can be found below.

Continuously Measure Digital Periods (High Frequency, 2 Counter Method)

https://decibel.ni.com/content/docs/DOC-11424

Let me know if this works!

[Henrik_Volkers]

Or use some  external FF  ->  frequency divider

But the two counter method (see excamples) should do it.

[ADI_Tony]

I used the 2 counter method and was able to measure period down to 112ns now.  Works great.  Will have to play with the divisor option as well to see how that works.  Thank you for the help!