Looking for a graphic tool for configurable and/or design

Hello,
I'm new to the forum and I looking for a graphical tool to create and or logic based on states, alarms and maybe measures of my system.
I would like to be able to create my "own" library of input sources, then the user can build up it's logic using the inputs and and, or or ">", .. blocks and the program should be able to output me a text file I can parse to do the "logic" defined by the user.
Can you suggest me an opensource project to do that, if any is available?
Thanks
Michele