Digital tab

How do I access Digital Alarm properties?
  1. In
    Library Repositories
    , select a library object that includes Logix tags.
  2. In
    Library Content
    , expand the
    FTAE
     folder and the
    Digital Alarms
     folder.
  3. In the
    Digital Alarms
     folder, select the alarm object, the
    Properties
     pane displays the digital alarm properties.
A digital alarm monitors a tag for one of the following alarm conditions:
  • If the value of the tag is equal to zero.
  • If the value of the tag is not equal to zero.
When a digital alarm is selected, the
Properties
 column of
Library Object Manager
 displays three tabs—
Digital
,
Status Tags
, and
Control Tags
.
The ellipsis (...) buttons following the text entry settings provide additional dialog boxes to assist in specifying the property.
Click
Apply
 to apply changes made in these tabs.
This table describes the settings in the
Digital
 tab.
Name
Setting Type
Description
Name
Text entry or Expression
The name that will be applied to the digital alarm when the library object is instantiated. This name will appear in the
Application Code Manager
 screens. The setting is populated with a default name based on the Tag name and library object for the selected Tag.
In a typical application, the default name should be used. Alternatively, a name can be entered manually in the
Name
 setting.
To create an expression, click the ellipsis (...) button to open the
Expression Builder
.
Include Condition
Text entry or Expression
Sets the condition under which the current Digital Alarm is instantiated. The default is
Always
. A condition can be entered manually or generated by an expression.
To create an expression, click the ellipsis (...) button to open the
Expression Builder
.
Input Tag
Text entry or Tag
The
ItemID
 that will be applied to the Digital Alarm when the library object is instantiated. The setting is populated with a default name based on the Tag name and library object for the selected Tag.
To browse to an alarm trigger tag, click the ellipsis (...) button to open the
Tag Browser
.
Condition
Dropdown menu
The condition that triggers the digital alarm:
  • Source <> 0
     The alarm becomes active if the value of the input tag is not equal to zero.
  • Source = 0
     The alarm becomes active if the value of the input tag is equal to zero.
Latched
Checkbox
Determines whether the alarm remains in effect if the condition is no longer met.
When selected, the alarm remains In Alarm, even if its alarm condition returns to normal. To allow a latched alarm to return to normal after its alarm condition returns to normal, the operator must reset the alarm.
To allow the alarm to return to normal after its alarm condition returns to normal without requiring operator intervention, clear the checkbox.
Severity
Text entry or Tag
The severity required for the event to activate the alarm.
Assign a severity level to the alarm to indicate the urgency of the In Alarm condition. The severity value can be a controller tag value or an integer value. If the severity value is an integer value, the range of values is 1 through 1000, where 1 is the least severe, and 1000 is the most severe. Ranges of alarm severities are mapped to four alarm priorities.
Do not use the alarm input tag itself to set its severity value. Input tags may not be updated correctly, and can at times be assigned bad or uncertain quality values (for example, when the connection to a controller is lost, or if a data server is rebooted).
To browse to a severity tag, click the ellipsis (...) button to open the
Tag Browser
.
Acknowledge required
Checkbox
Determines whether an acknowledgment is required to turn off the alarm.
If the alarm does not require acknowledgment by an operator, clear the checkbox. Most alarms are configured to require acknowledgment, but there may be events that are not displayed to operators that do not require acknowledgment. Alarms configured to not require acknowledgment are always in the acknowledged state, even when they are in alarm.
Minimum duration
Text entry
The minimum duration required for the event to activate the alarm.
Specify the minimum amount of time that the alarm condition must be true before the alarm condition becomes active. Set the duration from 0 to 600 seconds. Use this setting to eliminate false alarms.
Show Alarm as Tag
Checkbox
Determines whether the alarm is shown as a tag.
Tags are used to monitor the status and operate on alarms programmatically at run time. Clients can read and write to the alarm tags to monitor and change alarm states. Select the checkbox to enable tags for this alarm. Clear the checkbox to disable tags for this alarm.
Message
Text entry, Message, or Expression
The text displayed when the digital alarm is triggered.
Enter a text message up to 255 characters long that describes the alarm condition.
Click
New
 to open the
Message Editor
 and create a message.
Click
Browse
 to select a pre-existing message from the
Message Browser
.
To create an expression, click the ellipsis (...) button to open the
Expression Builder
.
ID
Read-only
The unique numeric ID for the message in the
Message
 setting.
New
Button
Opens the
Message Editor
 to create a message.
Edit
Button
Opens the
Message Editor
 to edit an existing message.
Browse
Button
Opens the
Message Browser
.
Associated Tags
Text entry or Tag
Up to four tags that may be included in the text of the digital alarm message.
In many cases, it is useful to have additional process information associated with an alarm. At runtime, the values of associated tags can be embedded in alarm messages.
To browse to a tag, click the ellipsis (...) button next to the tag to open the
Tag Browser
.
Alarm Class
Text entry or Expression
The class for the digital alarm.
Type a classification string for the alarm that allows filtering of alarms at run time. For example, use an alarm class to associate alarms together by function, such as those that monitor for valves that fail to open and close.
The alarm class text can be up to 40 characters long.
To create an expression, click the ellipsis (...) button to open the Expression Builder.
FactoryTalk View
 Command
Text entry or Expression
The
FactoryTalk®
command that is executed when the alarm is triggered.
Type a
FactoryTalk View
 command, up to 1000 characters long, to associate with the alarm.
To create an expression, click the ellipsis (...) button to open the
Expression Builder
.
Alarm Group
Text entry or Expression
The Alarm group that the alarm will be associated to.
The setting is populated with a default reference type parameter based on the tag name for the selected tag when an alarm is created. Can be entered manually or generated by an expression.
To create an expression, click the ellipsis (...) button to open the
Expression Builder
.
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