fun with sdaq and plotdat

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fun with sdaq and plotdat

Postby Doug Coulter » Mon Jul 30, 2012 12:52 pm

I've been working on a new thing to eventually be made available thought DJ's. This is a data aq device, USB interface, and some PC software to log data and then plot it with various mappings. All that, along with most of the details of the hardware design are already posted up here in appropriate threads for embedded and PC software, but without seeing what it does, it doesn't mean much. So, here's what it does for me.

Sdaq allows our standard counter uP board to have two counter and 4 a/d inputs, all sampled on the second, time aligned and time-stamped. The sdaq software shows real time 2d plots of counts and a/d inputs, scaled so that you can see if you're getting good data - not to the final units involved, but to make sure you're in range of the a/d or counter limits. Once a log file is acquired, we can really start having some fun with plotdat, which currently allows up to 4 dimensional scatter plots (x,y,z, color) and might later be extended to another couple dimensions - shape and size come to mind there. It uses gnuplot to do the plotting, but saves you from having to learn yet another very arcane command language for that - the dox are there, but...let me tell you, it took lots of tries to get what I wanted despite reading them closely, and only in hindsight did much of it make any sense whatever. Plotdat allows you to define mapping onto each axis from any of the input data - or, and importantly - any combination of the input data on any axis using any math and scaling that is supported by the language in question - perl - which means pretty much everything is there for you. Here's a screen shot of the two instances of plotdat that produced the movie I will embed as soon as it finishes uploading (1920p gets real big even for short movies).
Screenshot-49.png
Screen shot of plotdat gui's. Note the math in the axes edit boxes - you can do anything!


And, nothing beats a movie if there's motion in what you wanna show:
http://youtu.be/J-B8Cq6MaSo
http://www.youtube.com/watch?v=J-B8Cq6MaSo


Future capabilities, other than more dimensions, might include some pretty nifty stuff if I add database support. Should be possible to combine plot data from more than one run for example, either with different or identical conditions (other than that it had a chance to cool down between short runs - something that DOES affect Q and output in my setup). Imagine seeing 5 runs, mapped onto different shape points, for example so you can still pick them apart visually, but see them all together. And so on and so forth. Ideas appreciated! This is going to be relatively inexpensive once we make a product of it, so I expect a few here and elsewhere will want into this tool - it's really nice, despite a few minor limitations (sample rate at the moment is 1/second, fixed, for example, since counts over shorter times are hard to make mean much unless you have super high count rates).
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Doug Coulter
 
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