Serial communications protocol for safety critical systems

Abstract

A method and system of establishing communications between at least two independent software modules in a safety critical system, such as a medical system, is provided. The design comprises providing a media connection between software modules, wherein the software modules employ a communications protocol and participate in a bi-directional master-slave relationship between a master module and a slave module. The design further comprises sending an arbitrary length of data between the master and slave modules, wherein the arbitrary length of data is used by the master module to control and obtain status from the slave module, and sending arbitrary data further enables the slave module to return data and status information to the master module. The design also employs a safety critical communications watchdog between the master and slave modules, wherein the safety critical communications watchdog monitors communications quality between the master and slave modules. The protocol comprises bytes transmitted using a packet consisting of a start indication, a message identifier, an optional service identifier, a class identifier, an arbitrary length of data pertinent to the medical device comprising optional data, a checksum, and a checksum complement.