The System provides diagnostic information in the form of LEDs on its CPU and other modules. Also, any faults that have occurred in the system can be viewed via the configuration tool, or these could also be transferred to the remote master station.
Faults like I/O module failure, communications failure (with local devices), are recorded by the DCS and stored in its persistent memory. If any fault which is critical to the functioning of the DCS occurs, the DCS enters FAULT mode and stops functioning.