Temp/time waveform chart jumps (zig zags) to initial value

[Quix_]

Hi all,

I am trying to use LabVIEW to measure the temperature of a few sensors while actively cooling a chamber. When measuring the temperature as it changes, the waveform chart fluctuates and jumps between the current value and the initial value, forming a weird zig zag pattern (png file). The saved txt file does not have this jumping, only the new temperature. Does anyone know why this might be happening and/or how to get it to show a continuous decline instead of the zig zag pattern? 

I am using LabVIEW to call a Python function which returns an array with the current temperature, so maybe that is the reason? The VI that I attached is a subVI.

Thanks

[altenbach]

Ah, where to start!

A chart has it's own internal buffer, so don't wire it to an ever-growing 2D array! All it needs it the data before you are building it into a 2D array. (you could also replace your chart with a graph)

Also:

• Please don't maximize the front panel and diagram to the screen. That is supper annoying!
• Please eliminate the property value nodes ("datalog"). Just branch from the wire going to the indicator. (ANd why would you read the property twice in parallel? seems redundant!). Once you eliminate the proerty nodes, you can remove the sequence structure. It is pointless.
• Use "built array" instead of "insert into array"
• Please use a reasonable connector pane!
• Use "high resolution relative second" for relative times. No need for timestamp datatypes.
• Your wait control has the wrong representation.

[altenbach · Accepted solution]

See if this can give you some ideas.... 

(I replaced the python with a simulation and replaced the file IO with a simple string indicator for simplicity).

[Quix_]

Thank you! 

I figured it was something I missed about making things. 

Sorry that the VI was a mess! I threw together a bunch of different components and took out others to try and eliminate some of the clutter. I definitely also have a bad habit of making everything much more convoluted and confusing for no reason, a problem I always have when doing any kind of programming. 

Thank you for the assistance and tips on making everything smoother and run better! I appreciate it a ton.