LabVIEW
averaging
Solved!
Hi Soran,
Do you have a VI which I can take a look at? One way to start is to use a combination of shift registers and compound arithmetic.
For the example below, I'll be using a random number as my data acquisition signal value:
,
So then the code runs at the first time, I would like to initialize the value with the first value received from the random number. After that I'll divide them by 5. Noticed that I have connected the random number value inside the while loop to the right side of the shift register. This is to replace the one of the stack of the stacked shift registers with the updated value (everything outside the while loop runs once). I would like to think of stacked shift register almost like a FIFO buffer.
Shift registers: http://www.ni.com/gettingstarted/labviewbasics/shiftregisters.htm
Else, you can do somethink like below:
Where I'm running the For loop 50 times to store the value from the signal into an array of 50 elements. Sum up all the elements and average them.
Or you can you queues to make something like a producer consumer architecture: http://www.ni.com/white-paper/3023/en/
Hope that helps
Warmest regards,
Lennard.C
@Soran wrote:
But it did not work as the all the Xis get exactly the same numbers and it means that the data that second Structure gets is exactly the same one that 1st, 3rd, 4th, and 5th one get. Do you know what the problem is here and why this idea does not work?
This is normal dataflow. All your indicators will get the same value, because they are reading the same wire. There will only be new data on the wire after the outer while loop has advanced to the next iteration and the data source has been read again.
You really should do a few basic LabVIEW tutorials first.
Hi Soran,
I believe the problem is that when the time has elapsed, you stopped the program and plot the thing at the XY graph. Problem is that when you stop the code, the graph clears (of course there is that uninitialized shift registers which holds the value of your latest past run results). The easiest way is to use queues via Producer Consumer architecture (http://www.ni.com/white-paper/3023/en/).
From the block diagram below, you can see that I have 2 while loops. One is the producer where I store the values from DAQ assistant in a queue while the lower loop is my consumer which I extract the data stored in the queue. So for every 100ms, Elapsed Time will send a True value to the case structure which stores the value to the queue (you'll need to play around with the DAQ Assistant settings). If not, the producer while loop runs the false case shown in the second screenshot. At the consumer while loop, there is a Get Queue Status.vi which checks for the status of the queues. Once there is 10 elements in the queue, I flush them out (true case structure runs) which gives you an array of 10 elements. I sum the array of 10 elements and divide them by their array size (should be 10) and plot it to a waveform chart. Else, the consumer while loop runs the false case (meaning no elements is flushed out and let the data to be buffered).
Just take the above screenshots as for your own reference. I'll leave the rest to you on how you want to adapt that concept in your code.
Hope that helps
Warmest regards,
Lennard.C
