The following sections describe how standard and device alarms are configured. For information on how to create a custom alarm, refer to the Custom Alarms topic. For information on alarm fields, refer to Events and Alarms Reference topic.
The following sections detail calculation and detection for the DeltaV standard alarm set.
Standard alarms use alarm calculations that are predefined in the DeltaV function blocks. You can select which of the alarm calculations you want the module to detect and present to the operator. For example, if you want only HI and LO alarms, select only those two. The module does not detect the other potential alarms.
Examples of Function Blocks with Standard Alarms
Function Block |
Standard Alarms |
| AI, Pulse Input, and Manual Loader function blocks | HI, HIHI, LO, LOLO |
| DI function block | DISC |
| PID, Fuzzy Logic Control, Alarm, and Ratio function blocks | HI, HIHI, LO, LOLO, DV_HI, DV_LO |
An example of a predefined alarm calculation is the HI alarm on the AI (analog input) function block. The HI alarm compares the PV to a limit value as follows:
HI alarm is true if PV > Alarm Limit (HI_LIM)To create a standard alarm, select the function block on the diagram in Control Studio, click the right mouse button and then click Assign Alarm. On the Block Alarms dialog, select the alarms you want to use. The system provides default information, including the name of the alarm, the alarm limit, and the alarm priority.
Assigning an Alarm Dialog Window
After you select the alarm, you can rename it. You can use any name that makes sense for your application, such as FLOW_HI. When the alarm is active, the system displays this name in DeltaV Operate and includes it in the Event Chronicle. Because FLOW_HI is a module parameter, it is displayed with a bell icon in the alarm window of Control Studio and in the DeltaV Explorer hierarchy.
You can also modify the default alarm limit and alarm priority. The alarm limit is the value above which you want FLOW_HI to activate an alarm. The alarm priority determines the color, sound, and importance to the operator. You must decide how important the FLOW_HI alarm is to your plant operation, as compared to the other possible alarms that could be occurring. Refer to the System Alarm Management topic for more details on alarm priority.
Finally, you can make each standard alarm conditional by selecting the Conditional alarming box. The Conditional alarming box extends the block alarm parameters, enabling you to use time delays or additional process conditions to avoid unnecessary alarms. Selecting this box makes all of the standard alarms conditional. The Conditional Alarming topic provides more detailed information.
Each standard process alarm (except for fail) uses two parameters with the following name relationship:
For example, the HI alarm shown in the preceding check box has the following parameters:
All standard alarms use a calculation according to the following form:
HI_ACT is true if PV > Alarm LimitThe system sends the alarm to DeltaV Operate when the HI_ACT parameter becomes true (HI_ACT is true when HI_LIM exceeds the limit value). All alarm calculations (that is, *_ACT) are basically true/false conditions, where the true condition indicates that the alarm is active. All alarms (for example, HI_ACT in the preceding discussion) display the configured alarm word (for example, High) in DeltaV Operate when there is an alarm.
The conditional alarming feature enables you to easily add alarm time delays and enable/disable alarms to minimize nuisance alarms.
For example, when an upstream pump is turned off, the downstream low flow alarm is temporarily not meaningful. The low flow alarm becomes a nuisance alarm when the pump is off and should be disabled. The LO_ENAB parameter can be used to dynamically enable/disable the alarm. When this pump is turned back on, it may be best for the low flow alarm to remain disabled for a short period of time, allowing the flow rate time to rise above the low flow alarm limit. The LO_ENAB_DELAY parameter causes a delay in setting an alarm immediately after the alarm has been enabled using the LO_ENAB parameter.
Function blocks and extended function blocks that have built-in standard alarms also support conditional alarming. Conditional alarming for a function block is enabled by selecting the context choice Assign Alarm and then checking the Conditional alarming check box. When conditional alarming is enabled, five new parameters are added to the block for each available ACT parameter (HI_ACT, HI_HI_ACT, LO_ACT, LO_LO_ACT, DV_HI_ACT, DV_LO_ACT and DISC_ACT). In the descriptions that follow, the term alarm_ is used to represent either HI, HI_HI, LO, LO_LO, DV_HI, DV_LO, OR DISC, depending to the particular alarm being configured. The ACT parameter indicates the current status of its alarm condition, with 1 (true) representing an alarm condition. The five additional parameters are:
alarm_ENAB – This parameter enables /disables conditional alarm processing for a single alarm. The default value for this parameter is enabled (1), when conditional alarming for a function block is enabled. You can write to the alarm_ENAB parameter to dynamically enable/disable the alarm based on external process conditions.
When alarm_ENAB is disabled (0):
alarm_DELAY_ON – This parameter delays the time (in seconds) that it takes for alarm_ACT to be true (1) after the alarm condition is detected. If the alarm condition clears before the delay time is reached, the alarm_ACT parameter remains false (0) and the timer is reset. Every time the alarm condition clears, the timer resets.
alarm_DELAY_OFF – This parameter delays the time (in seconds) that it takes for alarm_ACT to be set to 0 (false) after the alarm condition clears. If the alarm condition reoccurs before the delay time is reached, the alarm_ACT parameter remains true (1) and the timer is reset. Every time the alarm condition is detected, the timer resets.
alarm_ENAB_DELAY – This parameter delays the time (in seconds) before alarm processing begins immediately after the alarm is enabled (alarm_ENAB becomes true). The alarm_ACT parameter is forced to 0 for the time specified (in seconds). The timer resets whenever alarm_ENAB goes from zero to 1.
alarm_HYS - This parameter is used as a deadband when resetting base alarm conditions for analog values. The block uses the value of alarm_HYS instead of the standard ALARM_HYS. When conditional alarm detection is enabled, the block uses ALARM_HYS as the deadband for deviation alarm conditions only.
Example
Conditional alarm behavior is influenced by the module and block execution scan rates. For example, if a module executes at a five second scan rate and a block in the module executes every 10 module scans, then the block runs every 50 seconds. If any conditional alarming delay is set to 50 seconds or less, the delay condition is met the next time the block runs. So if the alarm condition is met, the alarm becomes active between 0 and 50 seconds after the alarm condition was met. If the delay condition was set to 51 seconds, the alarm would become active between 51 and 100 seconds after the alarm condition was met.
PID, FLC, ALM and RTO are designed to minimize nuisance deviation alarms due to SP changes. The DV_HI_ACT or DV_LO_ACT parameters available in these blocks are forced to false for a period of time after a setpoint change is made that is large enough to (without the suppression) cause the deviation alarm condition to become active immediately. Changes in SP when the block is in Cas or RCas mode do not impact the calculation.
The ACT parameter is forced to False until the deviation alarm condition would normally be reset (if it had not been suppressed).
For example, if the deviation limit is 2 and a SP change of 3 is made, a deviation alarm would typically occur. However, since this deviation is due to a user SP change, the deviation alarm is disabled until the error (SP-PV) is less than 2.
DeltaV Operate is the alarm presentation vehicle in the DeltaV system. The presentation is based on the alarm properties and the alarm type. Refer to the System Alarm Management and Alarm Presentation topics for more details on configuring the alarm presentation.
All the alarms you add to a module, whether custom or standard, appear in the Alarms window in Control Studio.
To modify a standard or custom alarm:
Fieldbus and HART devices support as many as four device alarms:
Certain fieldbus devices may have only two device alarms: Not Communicating (COMM_ALM) and abnormal (ABNORM_ALM). The meaning of an abnormal alarm function depends on the device type.
Refer to the device documentation for a more specific description of the parameters.
The interface shows the individual alarms for a fieldbus device in the right pane of the DeltaV Explorer along with their configurable parameters. The interface for HART devices in the Explorer hierarchy is similar.
For HART devices and HART device templates, the system also provides a dialog that enables you to assign HART device conditions to one of the four device alarms. HART device definitions support the Alarm Conditions dialog in read-only mode so that you can see the factory-defined relationships between conditions and alarms. Note that if you change a FAILED condition to MAINTENANCE or ADVISORY, or if you change a MAINTENANCE or ADVISORY condition to FAILED, the device itself does not change its behavior in terms of how it sets its output. Only alarming behavior is affected. Launch the Alarms Conditions dialog from the Alarms & Events tab of the device properties.
You can assign the HART status conditions and DeltaV subsystem alarm conditions to one of the four alarms for all HART devices as shown in the graphic below (SIS tab is also visible when the device is connected to a Logic Solver).
For certain Emerson PlantWeb HART devices, you can also assign device-specific conditions (from standard HART command 48) to one of the four device alarms:
Device alarms can be enabled to participate in the DeltaV alarm interface tools such as the alarm banner and the alarm summary. Refer to Device Alarm Requirements for more information.
In order for the device alarms to participate in the DeltaV system, make sure that:
Also:
Fieldbus and HART device alarms are enabled by default when you add a new device to the control network from the Explorer library.
You can change the enabled/disabled status of the alarms for the device as a whole and for each individual alarm. The enable/disable setting for the device is on the Alarms & Displays tab of the device properties dialog. To access the setting:
The Enable Device Alarms property determines whether the alarms are available within the DeltaV system. If this box is not checked, the alarms will not be available through parameter browsers. In addition, the individual alarms do not appear in the Explorer and device alarm communications will not be attempted with the device. If you disable device alarms for a device, any configurable properties of the individual alarms (alarm enable and priority) are discarded. If the device alarms for a device are subsequently enabled again, the configurable properties are set to their default values.
You enable or disable individual alarms as follows:
The enabled/disabled property for the individual alarms corresponds to the .ENAB field for the alarm. Control modules, OPC client applications and Operators using displays can change the .ENAB field for the alarm.
Note For fieldbus devices, changing the .ENAB field for a device alarm does not change the corresponding alarm enable status in the field device. Also note that when you download the field device (along with the device alarms), the corresponding enable is set to be consistent with the setting in the field device.
In general, it is possible to read and write the parameter fields of device alarms from control modules that run in the same node. This type of reading and writing is typically limited to enabling or disabling certain device alarms based on the operating state of the module. For example, you might want to disable advisory alarms, which depend on the process to be active to work properly, when the unit is idle.
Hardware alarms appear as a subsystem under the node in DeltaV Explorer. This subsystem must be enabled for the system to detect the alarm condition and categorize it into one of the four hardware alarms. The Hardware Alarms subsystem is enabled from the node's properties dialog by selecting the "Enable System Hardware Alarms" option. Hardware alarms for I/O cards are enabled with the controller under which they reside. Once enabled, the hierarchy view displays the hardware alarm subsystem.
Once enabled, you can select the Hardware Alarms subsystem and configure the hardware alarm's properties.
Note Hardware alarms are not supported on remote workstations.
Each alarm can be enabled (or disabled), the default priority can be changed (this changes how operators see the alarm in the alarm banner, refer to Alarm Presentation) and the alarm suppression timeout can be configured (except on COMM_ALM). To get to the alarm's properties dialog, expand the node, select Hardware Alarms and in the right pane, select the alarm (ADVISE_ALM, for example). Right click and select Properties from the context menu.
Hardware Alarm state is retained through most partial downloads to the node. Condition state is reset on total downloads to the node; thus, after a total download, all hardware conditions become unsuppressed and the active timestamps are re-established (if the conditions are re-detected).
Note There are exceptions to what is retained during a partial download to the node. For example, I/O cards undergoing major changes (number of channels, card type changes and so on) will have the hardware condition reset. Cards not undergoing such changes will have their condition preserved during the partial download.
The alarm's properties settings are downloaded to the node when performing a total download, setup data download, or changed setup data download. The hardware alarm can be enabled/disabled by writing to the alarm's PRI field (that is, <node>/FAILED_ALM.PRI). This value cannot be uploaded.
Hardware Alarm condition suppression state survives redundant node switchovers; that is, all suppressed conditions do not unsuppress themselves because of a switchover.
External mechanical assets such as turbines, engines, pumps, and motors, and external optimization assets report alerts in one of the following alarms:
Use the DeltaV Explorer to configure asset alarms (after you enable Asset Optimization Alarms in System Preferences). Configuration involves adding an External Asset Server to an Application Station, configuring the server properties, synchronizing the server configuration with the DeltaV system, and configuring properties for the plant hierarchy, asset folders, and assets. The connection with the External Asset Server is made through the server connection URL and the server access credentials (user name and password). The server connection URL and server access credentials are configured in the Server Properties dialog box. Be sure to download the workstation after configuring asset alarms.
Refer to the Getting Started with Your DeltaV Digital Automation System manual for information on adding an Application station to the DeltaV Explorer. From the Application station, click External Asset Interfaces/New External Server to add an External Interface Server to the configuration. Once an External Asset Server has been added to the DeltaV system, you can delete it, rename it, configure its properties and synchronize its configuration with the DeltaV system. Use the What's This help for information on the fields in the Properties dialog. Here are a few things to keep in mind when configuring the server properties:
The Synchronize Configuration command synchronizes the configuration of the DeltaV system with the asset server. Any differences between the DeltaV system and the asset server are changed on the DeltaV system. Synchronization does not affect the configuration of the external asset system. Select the Asset Server, right click and select Synchronize Configuration to open the Synchronize Configuration Wizard. Use this Wizard to make decisions about new assets that have not been added to the DeltaV system and old assets that no longer exist on the External Asset Server. Be sure to read the help text in the left pane of every screen. Successfully completing the Wizard builds the Plant Hierarchy structure. Refer to Configuring Asset Properties for helpful information about using the Wizard to customize multiple asset properties.
The following figure shows a plant hierarchy that was built in the DeltaV Explorer under the Application Station after the server configuration was successfully synchronized with the DeltaV system.
The plant hierarchy name and asset folder names come directly from the Asset Server and cannot be renamed. They can be deleted. If you delete a plant hierarchy or asset folder from the hierarchy in the DeltaV Explorer, all subordinate objects are also deleted. Be aware that if an asset is deleted from the Explorer hierarchy but remains configured on the external asset server, it will show up again in the DeltaV Explorer when the configuration is resynchronized unless it is deleted during synchronization. Configuration options for the plant hierarchy and asset folders include adding a description and associating alarms and events with a DeltaV plant area. When alarms and events are associated with a plant area from the plant hierarchy or asset folders levels, all subordinate asset alarms are included in the association. This enables large groups of asset alarms to be easily assigned to a single area. However, an area can also be associated with a lower level asset folder. In addition, an individual asset can be associated with a control module for area association. Association at a lower level takes precedence over a higher level.
You can use the Wizard during the synchronize configuration operation to configure the properties of multiple assets. You can also configure individual asset properties after an asset has been added to a Plant Hierarchy in the DeltaV Explorer. Use Control/Select in the Wizard to select multiple assets and then click the Create button to customize the properties. Use the What's This help for information on the fields in the Property dialog boxes and use the help in the left pane of the Wizard. When assets are added to the DeltaV system, the system checks the names to ensure that no naming conflicts exist between the asset and other modules. The system automatically modifies an asset name during synchronization if a naming conflict occurs and includes the asset's original name in the asset's descriptor. If you customize an asset name through the Wizard, be sure that you observe DeltaV naming conventions. Otherwise, you will get an error message and the asset will not be added to the plant hierarchy. Refer to module naming conventions for information. Asset configuration options include adding a description, associating a primary control display and faceplate display with an asset, enabling and configuring asset alarms, and associating assets with a DeltaV plant area or module. Assets can be deleted from an asset folder and renamed. If an asset is deleted from the DeltaV system, but remains configured on the external asset system, the asset will reappear in an asset folder when the configuration is synchronized again unless the asset is deleted during synchronization.
Description
A default description is taken from the asset server. Because the
description appears in the DeltaV Operate Alarm Banner and Alarm Summary, it is
highly recommended that you ensure that the description is meaningful to
operators.
Primary Control and Faceplate Displays
Like other DeltaV device alarms, asset alarms can be associated with a faceplate
display that operators use to respond to alarms on the asset. The default asset
alarms faceplate is Asset_FP. Similarly, assets can be assigned to a primary
control display. Refer to Responding
to Alarms for information on the asset alarm faceplate and primary control
displays.
Area Associations
Assets can be associated with a plant area for alarm and event
reporting. Area associations can be made at the workstation, plant hierarchy,
and asset folder levels. All subordinate levels are included in the area
association of the parent level unless the subordinate level is associated with
a different area. Review plant
areas for more information.
Module Associations
Assets can be associated with modules. For example, the vibration alarms for
a pump can be detected and reported through an asset module while the pump is
monitored and operated through a control module. An asset associated with a
module is associated with the same plant area and, if applicable, the same
unit/equipment/control module as the associated module. The asset is also moved
if the associated module is moved to a different area. This ensures that all
alarms, both asset and control alarms for a single piece of equipment, are
always reported in the same area. If the associated module is deleted, the asset
alarm's area association is determined by the asset's parent level in the
hierarchy.
Enabling and Disabling Asset Alarms
Like other alarms, asset alarms must be enabled in order to be visible to
the DeltaV system. Alarms can be enabled/disabled for an individual asset
through the Alarm page of the Asset Property dialog and enabled/disabled for an
asset and all subordinate assets through the Disable/Enable All Asset Alarms
commands on the asset's context menu.
The presentation and response to asset alarms in the DeltaV system is similar to other device alarms. Review the following topics for information:
Use the DeltaV Diagnostics program to diagnose problems at the External Asset Interfaces Subsystem and server levels. Refer to Books Online and the DeltaV Diagnostics help for information on using DeltaV Diagnostics.
For asset alarms to participate in the DeltaV system, be sure that: