Various systems for measurement of a specimen are provided. Specifically, embodiments of the present invention relate to defining a trace using process data, the trace comprising a collection of events, analyzing the trace to detect nodes and arcs between the nodes using relationships between the collection of events, and detecting interleaving in the arcs by analyzing relationships between the collection of events and the detected nodes and arcs. When shutters for shutting out light from the optical connectors are collided with each other, the shutters move to positions where they do not shut out the light. by using at least two network nodes in parallel.