thanks for your fast answer.
My robot is based on hFramework. I planned to to switch to Mbed, but this is not done until now and I want to do one step after the other. At the moment my RPI image is broken (roscore does not start anymore - cannot connect to ROS master) so I have to do a fresh install and want to use this for an upgrade.
Is there any other possibility to communicate from RPI with hFramework or to get ros-core-client to work on a RPI without using a provided image?