Nightly builds of ProB 2 for Rodin 3 can be obtained from within Rodin using the update site http://nightly.cobra.cs.uni-duesseldorf.de/prob2/updates/nightly/. This version of ProB is deprecated. We recommend that you either use the standard plugin for Rodin (which still uses the old Java API) or use the new ProB2 UI based on Java FX which can also directly load machines from Rodin workspaces.