#$%^&*AU2011254043A120120119.pdf#####ABSTRACT A bandwidth efficient communications protocol for communicating between software modules in a medical device, the communications protocol comprising bytes transmitted using a packet including: a start indication, a message identifier, an optional service identifier a class identifier an optional length of data pertinent to the medical device a checksum and a checksum complement. C:\NRPornb[\DCC\JXA\4008956I DOC - 22/11/11