Acquire mA continuously and average only when the "average" button is pressed.

[Ayoob]

I want to acquire 4-20mA from flow meters continuously and show as "live values" and average the live values for a particular period decided by the press of a button. Every time I press the start/stop averaging buttons, the mean value should update to the new mean value.

I did the program using queue and 2 loops and averaging works fine. But once I stop averaging, start averaging won't work again unless I rerun the whole program.

Can someone look into the vi.

[GerdW]

Hi Ayoob,

unfortunately you attached your VI in LV2019. Using an older LabVIEW version might get you more audience. (I would like LV2017…)

Basic concept:

• the producer sends DAQ data into a queue when you want to do averaging.
• the consumer reads the DAQ data and calculates the average. In case of "TimeOut" (while reading the queue) the average calculation is reset…

[Ayoob]

Thanks GerdW

Updated the file to LV2016. Can you check now.

[GerdW · Accepted solution]

Hi Ayoob,

use less DDT wires…

When reading multiple channels with multiple samples you should get a 2D array after the DAQAssistent (instead of your 1D array)!

[Henrik_Volkers]

I would always compute the mean, show both in a chart with legend and the operator can select what he wants to see.

(Hint: Make the mean the first channel, looks better 😉 )

[Ayoob]

Thanks GerdW,

I was trying to show the number of samples averaged (or tie of averaging). I implemented it using 2 feedback node. It works.

[GerdW]

Hi Ayoob,

again you attached your VI just for LV2019…

I implemented it using 2 feedback node.

Wow, that looks complicated!

Why not simply use ArraySize (or MatrixSize) to read the number of samples and add them up using a (read: "one") shift register?

[Ayoob]

Hi GerdW,

Sorry i forget to change the version.

I knew there will be a better way, but still i tried to find a solution of my own. I tried the array/matrix method also but did not use shift register. I will try that.

[GerdW]

Hi Ayoob,

one shift register is enough:

[Ayoob]

Hi GerdW,

Im facing a problem using this method. It looks like the mean I am getting is a moving average. But what I need is a single average of all values between pressing start and stop the same like what happens in the attached program. Is there any solution for that. I tried many ways but data flow makes the program freeze at different places.

Attached is the first version I made. averaging in this version is good, but in this one when I press the stop button the live reading also stops.