In order to run FusionDebug 3 (or higher) against Railo on the Caucho Resin platform, Resin must be configured to allow debugging connections.
This is configured in RESIN_HOME\conf\resin.conf
to the list.
If debugging has been configured, you will see:
Listening for transport dt_socket at address: 8000
as the first line of the Resin startup.