This paper introduces the architecture of the Fault Analysis Software Tool (FAST). The tool identifies analytical redundancies from a reduced process description and use them to provide fault detection and isolation (FDI). In this form, the automated supervision of industrial processes is simplified. FAST can operate either stand alone in simulation mode (off-line) by reading the measured values from data files, or on-line connected to the process plant through an OPC interface. The OPC interface allows the tool to be connected to almost any process which features a SCADA system for supervisory control. When running in on-line mode, each process is monitored by a software agent. In case of a fault, FAST will detect it and will indicate the faulty device to the SCADA. The SCADA can display and record the fault allowing the implementation of early countermeasures. For some faults, FAST can also automatically reconfigure the process to temporarily avoid an emergency stop. This functionality is specially useful in systems with high level of autonomy, difficult access or for which maintenance operations cannot be immediately implemented. The objective of FAST is to provide to the industry a tool which can be used with a moderate level of complexity to apply FDI on top of the traditional process supervision.