I have installed EM 12c.
In it I added two nodes of a RAC cluster I have.
My problem is, that I cannot discover the databases on the nodes.
The listeners and database are up and running on the nodes, I can connect (with SQLPLUS) to the databases on the nodes from the OEM server.
Please direct me step by step if you can, or ask me for additional info that I may have neglected.
Not sure what you mean by "not being able to discover databases". Are you seeing an error? By default the discovered targets are in the unpromoted status. Have you looked at the list of unpromoted targets (setup --> add target --> auto-discovery results, non-host targets tab)?