Gnuplot is my friend...

[DamonHD]

I've been finally making friends with this (free) beast and my latest effort is a simple real-time graph of the battery voltage of my off-grid system, trivial I know, but I intend to spruce it up a little with time...

http://www.earth.org.uk/off-grid-stats.html

Lots of other data to write up and graph... http://www.earth.org.uk/note-on-data.html

Rgds

Damon

[Rover]

I Like it !

I  use ZedGraph, but requires programming and the proper OS.

[TomW]

HD;

Used it a LOT myself before the equipment I was using to log data with died.

Steep learning curve but very flexible.

Tom

[DamonHD]

I've added in a comparative line for the previous day.

Most of the complexity comes from the calendar stuff...  %-P

Rgds

Damon