2 Introduction

The topology discovery process is used to measure the time required for a signal to travel between two 10BASE‑T1S nodes on a network mixing segment. The physical distance between nodes is derived from a time-of-flight measurement on the physical medium transmission line. The process to make the necessary measurements and perform the calculation is defined in the OPEN Alliance 10BASE‑T1S Topology Discovery specification.

The topology discovery process requires the coordination of all nodes on the mixing segment. During the process, two nodes will have a designated function as either the reference or measured node. During the process, none of the other nodes on the mixing segment may transmit any signal, pulse, or message on the line. This application note details the role of each node and how to implement the measurement using standard registers. It does not suggest a particular management protocol.