> ## Documentation Index > Fetch the complete documentation index at: https://documentation.kodelabs.com/llms.txt > Use this file to discover all available pages before exploring further. # What is Fault Detection and Diagnostics? > Understand how FDD uses events, incidents, and faults to monitor building equipment and detect operational issues in real time. FDD monitors building equipment in real time to detect operational faults, track events, and group related issues into incidents. The module organizes fault data across three levels so you can respond to immediate problems and analyze long-term patterns. Open FDD from the Cloud BMS portfolio or building sidebar. ## Core concepts A fault is a period of time in which a specified condition is true on a specific device. Each fault has a start time, an affected device, a condition, and a duration. Fault definition showing four components: Start Time at 8:00am, Device AHU-1, Condition could not maintain discharge temperature within setpoint, and Duration for 5 hours FDD structures fault information into three levels: events, incidents, and faults. Each level serves a different purpose, from real-time response to long-term trend analysis. ### Events Events check multiple inputs across one or more devices. Each event carries an importance level and can serve as both an instantaneous indicator and a data point for analysis over time. Events alone can produce excessive output. Combine events with incidents and faults for actionable insight. Events page showing Pause Streaming, Last 7 Days date range, Filters, priority cards for Total 297, Life-Safety 0, Critical 2, Warning 66, and Alert 229, and a Table View of active events with Name, Device, Device Type, Point Name, Point Value, Start Time, End Time, Duration, and Ack'ed columns Selecting an event opens the event report with automated device trend charts and a details sidebar for investigation. Event report for Discharge Fan Operation Failure showing a trend chart with Discharge Fan Status point, a red highlighted fault period, and a Details sidebar displaying Event State as Closed, Priority as Critical, Point Name, Point Value, Start Time, End Time, Duration of 9 minutes, Device FCU208, and Area Floor 2 | Example event | Description | | ---------------------------------------- | ---------------------------------------------------------------------- | | Heating Not Active when Heating Required | The heating system is not running despite a heating demand signal | | Discharge Air Flow Lower than Expected | Measured airflow falls below the expected value for current conditions | | Simultaneous Heating and Cooling | Both heating and cooling systems are active at the same time | ### Incidents Incidents sit at the highest level. FDD creates incidents by finding commonalities between event groups using Reference Based Grouping. This method looks along ontology relationships to identify related equipment. For example, if a VAV cannot meet its setpoint, FDD checks the upstream AHU and sibling VAVs to determine whether the issue is isolated or systemic. Grouping related events under a single incident reduces the number of individual issues you need to investigate. Incident report for 260512-89642 with 36 VAVs showing Number of Events 85, Average Event Duration about 6 hours, Affected Areas 15, a Status gauge chart at 100% Closed, an Areas bar chart with Count and Avg Duration by floor, Domains pie chart showing Air Quality, Cooling Issue, and Heating Issue, Device Types pie chart, and a Details sidebar with Incident State Closed, Priority Alert, Start Time, End Time, Duration about 12 hours, and Building The Overall Impact timeline shows which routines triggered events over the incident period. The table below lists all contributing events with their device, point data, duration, and priority. Incident report showing Overall Impact timeline with CO2 Near Max Setpoint, Damper Fully Open for Long Periods, and Flow Less Than Setpoint routines displayed as colored bars across the time axis, and a Table View listing events with columns for Name, Device, Device Type, Point Name, Point Value, Start Time, End Time, Duration, Priority, Work Order URL, SLA, Area, and Ack'ed Reference Based Grouping does not achieve a 100% catch rate. Some fault patterns may not group into incidents automatically. ### Faults Faults capture long-term or recurring issues across your equipment. Use faults to monitor trends, triage recurring problems, and prioritize maintenance over time. Faults are not designed for instant alerts or root-cause analysis. They complement events and incidents by providing a broader view of equipment health across days, weeks, or months. Fault report for Sensor Failure Out-of-Range Discharge Air Temperature showing a point trend chart for Discharge Air Temp over a two-week period with Combined, Lines, and Bars display options, and a Details sidebar displaying Description, Occurrences 1, Avg Duration 18 days, Daily Avg Occurrences 1, Last Comment, Last Activity, Last Work Order, Area Ground Floor, Device Report link, and Routine Report link ## Priority levels FDD assigns a priority level to each event, incident, and fault. The default configuration includes five levels: | Priority | Purpose | | --------------- | ---------------------------------------------------------- | | **Life Safety** | Conditions that pose an immediate safety risk | | **Critical** | Severe operational failures requiring urgent attention | | **Warning** | Conditions that may lead to equipment damage or discomfort | | **Alert** | Minor deviations from expected operation | | **Info** | Informational conditions for awareness only | Admins can customize priorities through the `Settings` page in the FDD module. You can configure between three and five priority levels with custom names, descriptions, colors, and SLA settings to match your organization's triage workflow. FDD Settings page showing the Priorities tab with Acknowledgment, Table Management, and Triage Rules tabs, listing five priority levels: Life-Safety with description Immediate action required to prevent serious harm, Critical with description Urgent issue affecting comfort energy or mechanical systems, Warning with description Prompt attention needed for potential risk, Alert with description System irregularity detected, and Info with description Non-urgent notification, each with No SLA status, a colored badge, Edit button, and visibility toggle ## Next steps Monitor and investigate real-time fault events across your building equipment. Set up monitoring rules and thresholds for your equipment. View building health at a glance with FDD dashboards.