Mr
Jacques Busseuil
(Thales Alenia Space)
The objective of this activity is the development of a ‘CAN solution’ to be used in platform and payload avionics of telecom satellites. The proposed CAN solution has to cover all the aspects related to the introduction of the CAN bus in telecom satellites, from the physical and protocol layer definition up to the test and validation procedure definition.
A breadboard system fully representative of the electrical architecture proposed for CAN, with both RS-485 and ISO transceivers, representative redundancy, data traffic, noise and faults injection capability will be developed allowing pre-qualification of the CAN solution proposed.
At the end of this study, the achieved results will represent the technical proof that a CAN SAT COM solution is feasible and it will be able to lead to money and time savings, bringing benefits in all engineering steps of the DH system development from design, integration up to verification.
This study will also provide a set of lessons learnt and recommendation that can be used to update the ECSS-E-ST-50-15 standard.
Summary
The SATCOM communication protocol is based on the following assumptions:
Bus rate: 512kbps
Number of nodes: 1 OBC with 1 CAN controller connected to two transceivers (selective bus architecture) + 120 Payload units, each with 1 CAN controller connected to two transceivers (selective bus architecture).
Every payload unit produces a 8-bytes TM every 32 s
4 Payload units are able to produce also a 8-bytes TM every 100 ms for AIT and test purposes.
OBC can issue at maximum 1 TC per sec
Due to the fact that in a CAN-RS485 network no more than 32 nodes can be accommodated, whereas a CAN-ISO network can be composed of up to 128 nodes, two different HW configurations are necessary, but the two proposed CAN solutions try to maintain commonalities in order to limit the number of tests to be performed specifically for each network topology.
