OpenMarine

I'm playing around with NodeRed and probably a little out of my depth

By cutting and pasting JSON strings, I have configured a few gauges from the SignalK stream
In the process of doing this I seem to have messed up the "out of the box" function nodes provided with OP0.9
eg Lat, Long COG etc

How can I restore those nodes?

How do I create the code for a new function node eg to display data like DTW


Can someone proved an idiots guide to editing the edit node - JSON path box as I dont understand it at all.

Thanks
Steve

OK so I installed a fresh OP 0.9 Noobs on a spare SDCard and it seems I didnt screw up the nodes ... they didnt work in the firstplace 
Only one that works out of the box is SOG
Frustrating