You XY plotting works well.
For people following this post the supplied demo code uses serial strings like #plotsweep~-177.4400~177.00~88.00~44.00~35.00 to represent 5 current analog values which are then plotted and replotted as each #plotsweep string is received. All great stuff.
From an arduino programming perspective you would need to build the serial character string as you read the analog inputs or any calculated variables which would be integers.
Obviously character strings may need to be built up from integers so the itoa function will be required maybe in format itoa (analog1,analog1_txt,10). The raw Analog would be stored into an array before processing.
Alan I like your future consideration of " User defined visualizers from definition files allowing layout of controls (like dials and gauges, sliders and buttons, graphs etc)"