CAN Implementation and Performance for Raman Laser Spectrometer (RLS) Instrument on Exomars 2020 Mission

Abstract

The use of CAN bus in space applications has increased during the last fifteen years. The need of standardizing not only the physical and link layers but also the higher layers protocol to meet spacecraft specific constraints or requirements, such as bus redundancy management, node monitoring and synchronization, has aroused. Therefore, a Working Group on CAN bus was stablished by ESA in collaboration with European Industry and Space Agencies, whose effort gave as result the publication of ECSS-E-ST-50-15C in 2015. This standard defines CAN protocol extensions for space use and specifies the optional use of the CANopen standard as higher layer to be used over CAN bus. The ExoMars Mission was chosen as spreadhead for the application of this standard. The present paper provides an experience report on this novel standardized use of CAN/CANopen in Space, in particular in the Raman Laser Spectrometer (RLS) that will be boarded into the Rover of ExoMars 2020. Even though RLS makes use of considerably long science telemetries (up to around 2Mbytes) CAN has been designated as its only data interface. We report on software, hardware and data transmission performances, as well as brief description on redundancy and synchronisation of this CAN implementation.