The present invention relates to systems and method for safely distributing software for electronic controllers in the refrigeration container industry. The present invention also concerns communication systems primarily for electronic controllers related to refrigeration containers. Tt is the object of this invention to achieve fast software distribution in container controllers. The object can be fulfilled by introducing a buffer memory in the communication system, which buffer memory comprises new container controller software version, which communication system distributes the new container controller software version by the communication means, towards receiving communication systems where the new software version is placed in the buffer memory. Hereby it can be achieved that software distribution starts automatically as soon as only one communication system comprises the new software version, this software version will in a very short period be spread into all container controllers e.g. on board a ship or in a container yard.