A top-down approach for realtime industrial-Ethernet networks using edge-colouring of conflict-multigraphs

This paper presents a top-down approach to design switched Ethernet networks based upon tree topologies for realtime automation systems. The approach considers each port of a switch as an exclusive networking resource and thus permits concurrent communication over different ports. We firstly focus on a class of special cases with unitary packet-sizes and transmission of each request in every production cycle-time. We point out that an off-line schedule can be generated independently for each switch with half-duplex connections. With the networking infrastructure and communication requirements as inputs, we present a scheduling method, which is based on the creation of a conflict-multigraph for each switch. The schedules are then realized by using a greedy edge-coloring. We also present first results of the coloring-process. Finally, we discuss various ways to implement the computed schedules with their assets and drawbacks