Hello!
I got fully configured Pi as profinet-master and some profinet slave connected to it. Now I need to change IP-addresses to migrate on other subnet. I don't want to update the project, but can I do it from program code?
So far, I can change IP of master using linux terminal (ifconfig), and IP with name of slave device by DCP_set functional block. Changing only the Master IP-address, all functioning fine, but when changing slave IP - topology is ruined and connection is lost.

OMG! I did it!
So:
1. You need to disable slave node and master by "NodeName.Enable := FALSE" and calling DED.Reconfigure functional block;
2. Call desired methods from IoDrvProfinetBase.ControllerConfigUtil functional block (e.g UpdateIPSettings, UpdateStationName, etc);
3. Enable back master and slave.
Thats how you can change IP of profinet slave node. Also you can update slave it-self by ProfinetCommon.DCP_Set.

I can't say, how much it safe enough, but it work's for me =)
Good luck!