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Fault tolerance in the Tricon is achieved by means of a Triple-Modular Redundant (TMR) architecture. The Tricon provides error-free, uninterrupted control in the presence of either hard failures of components, or transient faults from internal or external sources.

The Tricon is designed with a fully triplicated architecture throughout, from the input modules through the main processors to the output modules. Every I/O module houses the circuitry for three independent channels, which are also referred to as legs.

Each channel on the input modules reads the process data and passes that information to its respective
main processor. The three main processors communicate with each other using a proprietary high-speed bus system called the TriBus. Once per scan, the three main processors synchronize and communicate with their two neighbors over the TriBus. The Tricon votes digital input data, compares output data, and sends copies of analog input data to each main processor.

The main processors execute the control program and send outputs generated by the control program to the output modules. The output data is voted on the output modules as close to the field as possible, which enables the Tricon to detect and compensate for any errors that might occur between the
voting and the final output driven to the field.

For each I/O module, the system can support an optional hot-spare module which takes control if a fault is detected on the primary module during operation. The hot-spare position can also be used for online system repairs.