System Alarm Management

Plant areas, alarm priorities, alarm types, and alarm states all affect the way the system manages individual alarms. Understanding these concepts is key to developing a good system alarm strategy. This section describes these system-wide concepts. For more information on events and alarms, refer to the Events and Alarms Reference topic.

Plant Areas

Each module is associated with a single plant area. Even if the module appears in the DeltaV Explorer under a unit module and the unit module is under a process cell, they are all under a plant area and, therefore, are associated with that plant area.

Devices and Area Association

Fieldbus and HART devices are also associated with areas. If the device is not associated with a control strategy its area defaults to the area of its associated controller or Logic Solver.

HART Device Area Association - HART device alerts default to the associated controller's alarm area (in the case of Logic Solvers, this is the Logic Solver's alarm area.). If you configure and saved an I/O block in a module that references the DST for the HART Device, the module's area becomes the alarm area for the device alerts. This area remains the associated alarm area until the reference or the module is deleted. If you delete the module, the area returns to the default controller area. If you rename the module, the new name is reflected as the associated module name for the device alerts. Also, if a second module is created with an I/O block referencing the same DST, the area remains assigned to the first module.

To change the area assignment, you must first delete the existing I/O reference in the existing module and then configure and save the different module with a new I/O reference.

You can find the area and module that the HART device alarms are currently associated with from the Alarms & Displays tab of the device properties dialog as shown below.

Fieldbus Device Area Association - When you assign a module's function block to the primary function block in a fieldbus device, the device is associated with the plant area (and unit) that contains the referencing module. The primary function block of a device is the function block with the lowest block index number. This block normally appears as the first block under the device in the DeltaV Explorer. For fieldbus devices, if the module is deleted or if the module function block associated with the primary function block in a fieldbus device is deleted, the device defaults to the area associated with its controller.

Workstations and Areas

Workstations can read and write parameters from anywhere in the system (unless restricted in the workstation properties dialog) and they can monitor events and maintain a list of active alarms in plant areas that have been assigned to the workstation's Alarms and Events subsystem.

Workstations also generate their own hardware alarms. The ability to report hardware alarms must be enabled in the workstation's properties dialog.  Hardware alarms can be displayed in the alarm banner and the alarm summary control. From the alarm summary control and DeltaV Diagnostics, you can run the Condition Summary application. This application lists the conditions that are causing the hardware alarms. The condition can be suppressed or made active from the Condition Summary.

Any module or device that has an alarm reports it to all workstations to which the module's area is assigned, as long as the workstations' Alarms and Events subsystems have been enabled. A workstation monitors (logs to the Event Chronicle) all events in the system that are associated with the plant areas assigned to it.

When you assign an area to a workstation and download it, you must log off the workstation and log on again before you can see the associated alarms in the Alarm List.

You can add as many as 99 plant areas and assign the plant areas to specific workstations. Make these changes through the DeltaV Explorer. To assign an area to the Alarms and Events subsystem for a workstation, select the area and drag and drop it to the workstation's Alarms and Events subsystem. To view the areas assigned to a workstation, click Alarms and Events (under the workstation name).

Note A module must also be assigned to the node where it is to execute (a controller or an Application Station is acceptable for some modules). This is done by assigning (dragging and dropping) the module to the Assigned Modules subsystem under the desired execution node.

If you do not want an operator to have the authority to control an area (that is, have write parameters in associated modules), you can configure your system so that the operator has no parameter writing privileges (security write keys) in that area. Subsequently, when that operator is logged on, alarms from that area are not displayed in the Alarm Banner or the Alarm List pictures. This way, you can control which alarms are seen by a particular operator. To define which areas a user is responsible for, define parameter security write keys for specific areas in the DeltaV User Manager. For information on how to lock alarm parameters, refer to the Parameter and Function Security topic.

Additionally, you can configure the workstation to restrict control to only the areas assigned to the workstation through the workstation's properties dialog. Therefore, when a user that has sitewide privileges logs on to the workstation, that user can only affect control to the areas assigned to the workstation. This prevents a user from controlling an area when the alarms cannot be displayed on the workstation. This is the default configuration when you create a workstation.

The workstation shows the alarms it processes to DeltaV Operate only if the current user has any parameter security write keys for the area that contains the alarm. For example:

Additionally, this user can only write to parameters in Areas C & D when logged on to this workstation (providing the user has the key for the lock to which the parameter is assigned).

Alarm Priorities

Alarm priorities indicate to the operator the importance of an alarm. The priority affects the order in which alarms appear in the Alarm Banner and the Alarm List pictures in DeltaV Operate.

The system presents all alarms that you configure with the same alarm priority the same way throughout the system. If you modify the definition of a particular alarm priority, all alarms configured using that alarm priority will use the new definition.

There are 12 possible alarm priority levels: numeric values 4 through 15 plus a special log only priority level (value 3). The highest priority value is 15 (it is used for the most important alarms).  The lowest priority value is 4.

DeltaV systems prior to release 5.x used a priority system with three alarm priority levels plus the special log only priority level (value 3):

For backward compatibility, version 5.x no longer uses priority levels 0,1 and 2 in new configurations but will automatically convert those old priority levels into one of the new levels (4-15).

Events with Log priority (level value 3) are not considered alarms. Use the Log priority to designate an event that is important enough to be recorded in the Event Chronicle but is not something the operator needs to be aware of. Events with Log priority are not displayed in the Alarm Banner and the Alarm List links and do not turn on the alarm horn.

By default, only four of the 12 (plus Log) priority levels are available for configuring alarm parameters in the system:

Default Alarm Priority Definitions

You can define up to eight additional priorities using the DeltaV Explorer. You can also modify the alarm priority names to better describe your alarm prioritizing system. Priority levels that are not explicitly configured are given the same properties as the next higher configured priority level.

The acknowledged status of the alarm, the current alarm state, the priority value, and the time stamp on the alarm determine the alarm's importance in the system. Alarms with the larger priority values have the higher importance. Refer to the Alarm Importance topic for more information.

The following figure shows the dialog in the Explorer for an alarm priority.

Setting Alarm Priority Properties Window

The alarm priority properties include the following:

Value - Determines the priority value of the alarm priority. The higher the number, the greater the importance of the alarm.

Auto Acknowledge New Alarms - Determines if alarms of this priority are automatically acknowledged at the time of alarm detection. The acknowledgment state of an alarm can affect flashing and the order in which alarms are presented in DeltaV Operate.

Auto Acknowledge when Inactive - Determines if alarms of this priority are automatically acknowledged when the condition causing the alarm clears. This means that the alarm would no longer be shown in the Alarm Banner or Alarm List pictures even if the operator never acknowledged the alarm.

Alarm Banner shows - Determines when alarms of this priority are displayed in the Alarm Banner. The choices are Not Hidden, Unit, and Module. Not Hidden specifies that active alarms of this priority are always shown in the Alarm Banner identified by its module (or device) name. The Module selection specifies that alarms of this priority should be identified by their module names and are not shown in the Alarm Banner if there is a more important alarm in Alarm Banner already showing this module name (the module would be identified at most once in the Alarm Banner). The Unit selection specifies that alarms of this priority should be identified by the name of the unit associated with this module, and these alarms are not shown in the Alarm Banner if there is a more important alarm in Alarm Banner already showing this the name of this unit (the unit would be identified, at most, once in the Alarm Banner).

Wave file - Determines the sound associated with active alarms of this priority. The DeltaV system includes several WAV format files. When you download the system, these files are copied to \DeltaV\data\sounds. When an alarm goes into the active state, the system plays a WAV file in a loop-back mode so that it sounds until the operator acknowledges the horn. You can disable the sound for alarms of a certain priority by deleting the WAV file reference. Alarms that are auto-acknowledged still play their wave files.

Alarm States

In the DeltaV system, alarms have six potential states, determined by the values of the fields of the alarm parameter. The following table shows the relationship between the alarm states and values of the alarm parameter fields:

Any time the state of an alarm changes, the system updates the alarm's information in DeltaV Operate and generates an alarm state change event that can be recorded in the Event Chronicles.

Alarm Types

An alarm type defines a set of characteristics that determine how alarms appear on displays and in the Event Chronicle. Each standard alarm is associated with one of these alarm types. If you create a custom alarm, you select or create the alarm type associated with it. Device alarms do not require alarm types. The alarm words are defined by the device's definition data, and the information communicated from the device is automatically converted into device alarm messages.

Note that the alarm type does not define an alarm calculation for the alarm, you must define the alarm calculation for custom alarms. See Custom Alarm Calculation for more information. A single alarm type can be assigned to several alarms to give them the same display characteristics.

There are 19 predefined alarm types. You can use these alarm types as they are, modify them, or create additional ones. Alarm type names are case sensitive.

Alarm Type Properties

Note %P1 and %P2 represent the values of user-defined parameters. When configuring an alarm with Control Studio, check to see if the alarm message expects any user-defined parameters. If so, configure which parameter in that module should be read at the time of alarm detection to replace the %P1 (and %P2) in the alarm message. User-defined parameters typically capture the value that caused the alarm, the limit value that was in effect at the time the alarm was detected, and so on.

When the custom alarm requires a message that is different from the available Alarm Types messages, you must create a new alarm type. Before trying to use the alarm type in assigning an alarm to a module, you must create the new alarm type.

The following figure shows the dialog in the Explorer for an alarm type.

Setting Alarm Type Properties Window

An alarm type determines the following:

Alarm word - Appears in DeltaV Operate when the alarm is active or unacknowledged. The alarm word can appear in the Alarm Banner, the Alarm List picture, and in the detail and faceplate displays for the standard DeltaV modules. When you create a custom display or an Alarm List, you have the option to make the alarm word or the alarm name appear in the display.

Although device and hardware alarms do not have an alarm type, they do have one of the following alarm words: COMM, FAILED, MAINT, ADVISE, and ABNORM (device alarm only).

Alarm category - Appears in the Event Chronicle for every alarm state change (state changes are listed in the Alarm States topic). You can use the category for sorting and filtering alarm data inside Event Chronicle.

Alarm message - Appears in the standard Alarm List picture. The alarm message is defined as the Description field. The message is also logged in the Event Chronicle.

For process alarms, the alarm message is a combination of text strings and variables that you supply in the following form:

text string %P1 text string %P2

where %P1 and %P2 represent parameter values. You define the parameters in the Optional Alarm Message Parameters section of the System Alarm Type dialog through the Explorer.

For example, if you want the operator to see a message like the following for an alarm:

High Alarm 80 Alarm Limit 72

you would type the following in the alarm message box:

High Alarm %P1 Alarm Limit %P2

and use the following parameters for %P1 and %P2:

Parameter 1: PV

Parameter 2: HI_LIM

For process alarms, the alarm message affects all the alarms associated with the alarm type unless you override both the message and message parameters for a specific alarm in Control Studio.

For device alarms, the alarm message is determined by the information available from the device for the most recent condition that caused the alarm. A device can report multiple alarms (for example, Failed, Maintenance and Advisory) Fieldbus devices that support PlantWeb alerts and the reannunciation feature report subsequent condition changes associated with the same alarm (Failed, Maintenance, or Advisory). This results in an unacknowledged alarm state. All other fieldbus devices do not report a second condition until the first condition clears.

Device alerts are resynchronized when you download the device or when communication with the device is disrupted and then restored. When resynchronization occurs, the alert condition reported may not be the most recent because the reporting order is not available in the device.

Alarm Importance

The acknowledged status of the alarm, the current alarm state, the priority value, and the time stamp on the alarm determine the alarm's importance in the system:

• Unacknowledged alarms have a higher importance than acknowledged alarms.
• After the acknowledgement status is considered, alarms that are still active are considered more important than alarms that have already cleared but have not been acknowledged by the operator yet.
• When more than one alarm has the same acknowledgment status and active status, alarms with larger priority values have the highest importance.
• When more than one alarm has the same priority value, active status, and acknowledgment status, the newer alarm has a higher importance.

For example, the most recent, acknowledged, active alarm with a priority value of 15 is the most important alarm in the system. Then, a new alarm occurs that is unacknowledged and has a priority value of 4. This new alarm is of higher importance than an acknowledged alarm with a priority value of 15 because of the acknowledgement status of the alarms.