A Tricon system must have a main chassis and may have up to14 expansion or remote expansion (RXM) chassis. The following configuration guidelines apply. Main Chassis Configuration Guidelines • There is one main chassis with a chassis address of 1. • The main chassis must contain three model 3008 Main Processors for Tricon v9.6 and later systems. • The main chassis must house two power modules. • The main chassis provides six logical slots for user-selected modules and one COM slot. • A v9 low-density configuration includes a v5–v8 chassis with v9 main processors, communication, and I/O modules. Expansion Chassis Configuration Guidelines • Expansion chassis are used when the total I/O bus cable length for the system is less than 100 feet (30 meters) for each channel. • Each expansion chassis must have a unique address between 2 and 15. This address must not be used by any other chassis. • Each expansion chassis must house two power modules. • One set of triplicated I/O bus cables is used to interconnect channels A, B and C between expansion chassis. • Each expansion chassis provides eight logical slots.