How to debug nodes?

Is ther any way to debug nodetrees. I mean, read the imput and output of nodes while program is running.

Use the print node … the concat string node is also very useful to create explicit messages. Then in order to easily refind those nodes, I use a different color for them and encapsulate them into a frame with special color too.

Thanks a lot. That’s what I need.
Step by step I’m going trough my project…