How to plot multichannel graph taking data from a queue (i.e. points of random channels one by one)?

[m@NI_forum]

Hello,

I am scanning 10 resistors (measuring resistance) using a multiplexer card PXI-2503 and a soursemeter Keithley 2400. As I'm reading data one by one and from each reading create a cluster containing a channel, time, resistance value. Then every cluster is sent to a queue.

Queue is used to write data to a TDMS file and also I would like to plot resistances of all channels on a graph vs time. The question is how to plot multichannel graph taking data from a queue (i.e. points of random channels one by one)?

[Gregory]

Hi m@NI_forum,

You can use an XY Graph. In a shift register, you will hold an array of XY graph data, which itself is a cluster of x-array and y-array. When you receive a new point, index to the correct XY data (using the channel #), add your new X and Y points to corresponding arrays, and reassemble your data.

You can use a nested "in place element structure" to access the array element and the cluster elements.

[m@NI_forum]

For some reason, I cannot find Build XY Graph VI in my palette. Is there a way to plot without using Build XY Graph VI? By the way, can I download Build XY Graph VI anywhere?

[Gregory · Accepted solution]

You can create an XY graph without the express VI, in fact I'd prefer if you did!

Here is an example of building the plot one point at a time. Note that it is not an example of good programming practice (no errors, typedefs, queue release, loop stopping) it is just meant to get you up and running.

[m@NI_forum]

Thank you. Could you please write me the name of the  tool? I cannot find it. Unfortunately, I cannot open your VI as I use an older version of LabVIEW.

[Bob_Schor]

The function is called "Build Array".  It exhibits "polymorphism", changing its appearance (and behavior) depending on what is wired to its input(s).  Drop one down on a Block Diagram and read its Help entry.

Bob Schor

[Gregory · Accepted solution]

Here it is for LV 2012

[m@NI_forum]

 gregoryj &  Bob_Schor, thank you both for answers. They are helpful. The VI works now.