Fieldbus and HART devices can report conditions directly to the DeltaV system.These conditions can range from potential problems such as hardware failures within the device, loop problems, and misconfigured parameters, to proactive reporting of upcoming maintenance needed.
Device condition functionality is dependent on the device. Fieldbus devices support either standard fieldbus alerts or PlantWeb alerts.
Standard fieldbus alerts - Devices report alerts in a single alarm: abnormal. This alarm is based on the standard Block Alarm definition.
PlantWeb alerts - Devices report alerts in one of three alarms: Failed, Maintenance, and Advisory. The first active alert condition is reported for its associated alarm. A device can report multiple alarms (Failed, Maintenance and Advisory) but only one alert condition at a time can drive the alarm. Fieldbus devices that support PlantWeb alerts and the reannunciation feature reannunciate alarms if another associated alert condition occurs for the alarm. For example, an acknowledged Maintenance alarm changes state to unacknowledged if a new Maintenance alert condition occurs.
Device alarms derived from PlantWeb alerts are visible through the operator alarm interface tools, such as the alarm banner and the alarm summary object. They are also visible in the DeltaV Explorer. Device alarms can be added to your DeltaV displays as well. They may also provide a recommended action based on alarms.
Although the alarm interface tools and operator displays give visibility to device alarms, the Diagnostics application remains the primary tool to find the cause of device integrity status problems.
Within DeltaV software, all fieldbus devices also have a communications failure (Not Communicating) alarm. This alarm is generated when DeltaV software recognizes that a device is no longer communicating on the H1 segment.
HART devices support either standard HART alarming or PlantWeb alerts:
Standard HART alarming - All HART devices connected to non-remote I/O report standard status information to a set of channel parameters. The DeltaV system assigns this information to three possible alarms: Failed, Maintenance, and Advisory.
PlantWeb alerts - Devices report status and specific diagnostic (command 48) information which the DeltaV system assigns to three possible alarms: Failed, Maintenance, and Advisory. Only the status values are also available as HART channel parameters.