Towards an experimental assessment of the slave elementary cycle synchronization in the Flexible Time-Triggered Replicated Star for Ethernet

The communication subsystem of distributed embedded systems (DES) that must operate continuously and satisfy unpredictable requirement changes must be reliable and flexible. Recently the Flexible Time-Triggered Replicated Star for Ethernet (FTTRS) has been proposed as a communication subsystem that satisfies these two attributes. It is based on the master/multi-slave Flexible-Time Triggered (FTT) communication paradigm and relies on two custom switches, each with its own embedded FTT master. Both masters are active simultaneously and provide the same service. Specifically, they simultaneously and periodically broadcast so-called trigger messages (TMs) in a redundant manner to make them robust to transient channel faults. One of the functions of these TMs is to divide the communication time into rounds called elementary cycles (ECs). For the correct operation of FTTRS, it is important that all slaves agree when each EC starts and ends. A mechanism to achieve this has been recently proposed. This paper presents a first implementation of this mechanism and a series of experimental tests that constitute a first step towards building a prototype of an FTTRS network.