triggering DAQ write to file

[Bentz]

I'm having trouble getting my DAQ to write data to a file based on an external analog input.  The challenge is that the input analog signal is only about 1ms long and I'm using an old cDAQ NI 9172.  The analog input is active low, so I want the program to write to the file when the voltage falls from 5V to <3V.

I can see the trigger fire when I run the program continuously, but it does not write to the file.

Any help would be greatly appreciated 🙂

[Dennis_Knutson]

You don't understand what you are doing with the dynamic data. You have 5000 samples and with the conversion to a scalar, taking the very last sample and doing your comparison to that. Really need to search through all your samples.

[Bentz]

Thank you for the quick reply 🙂

You are probably right that I don't understand the dynamic data type.  I am pretty new to LabVIEW.  How do I go about searching through all of my samples?  I am confused by this because the numeric indicator I attached at the output of the converter changes continuously with the dynamic data.  It doesn't just show the final value of the 5000 samples. 

I was following this post when I was doing this:

http://forums.ni.com/t5/LabVIEW/boolean-troubleshooting/m-p/725593#M332053

http://forums.ni.com/ni/attachments/ni/170/332053/1/ConvertSingleScalar.png

Thank you for the help

[Bentz]

Hmm my last post was incorrect.  I was going off of memory.  The numeric indicator does indeed only update every half second.

[Bentz · Accepted solution]

I think I figured it out.  Or at least I did something that works now.  I added the "Array Max and Min" function which lets me read only the min of the data and then compare for the write enable.