An Alarm Condition is an indication of an abnormal state. Examples of Alarm Condition include:
In Fernhill SCADA some tag types automatically generate alarms when an abnormal condition occurs. The Channel Tag will raise an alarm if the communication channel fails.
You can also define your own alarms using these tags:
An Alarm Condition has four main states: Normal, Active, Acknowledged, and Cleared.
![]() | Normal: There is no abnormal condition and the alarm is not active. Active Alarm: The abnormal condition has been detected. Acknowledged Alarm: The alarm has been acknowledged by a user (the abnormal condition is still present). Cleared Alarm: The abnormal condition is no longer present, but the previous abnormal condition has not yet been acknowledged. |
Once an Alarm Condition becomes active, the alarm cannot return to normal until both of the following occur:
Sometimes a nuisance alarm occurs where the abnormal condition is detected and cleared repeatedly. This might be caused by a faulty sensor, or intermittent connection, or a deadband that is too narrow. In such situations is may be appropriate to disable the alarm to prevent user distraction.
Fernhill SCADA allows operators to disable alarms. Use the Disable Alarms Tag Command to disable alarms. Use the Enable Alarms Tag Command to enable alarms.
Each alarm is assigned a severity value that ranges from 1 to 1000. The lowest severity is 1 and the highest severity is 1000.
Fernhill SCADA assigns a color indicating the relative severity of the alarm. The default severity mapping is:
Severity | Property | Default Color |
---|---|---|
750 - 1000 | P1AlarmColor | |
500 - 749 | P2AlarmColor | |
250 - 499 | P3AlarmColor | |
1 - 249 | P4AlarmColor |
Note: Edit the properties of the Database Root Tag to change the colors assigned to alarms.
You can configure Fernhill SCADA to automatically send alarms using email with the Alarm Router Tag.
The Alarm Router Tag supports:
You can access the alarm list using:
All options allow you to view the active alarms and optionally acknowledge alarms.
You can access alarm data from other programs using any of these methods:
You can use this type of SQL query to query alarms:
SELECT SourceName,ConditionName,UpdateTime,Message,Severity,StateAsText AS "State" FROM Alarms WHERE State = 1 -- Enabled, inactive, not acknowledged OR State = 3 -- Enabled, active, not acknowledged OR State = 7 -- Enabled, active and acknowledged
The above query can be used with these data access interfaces:
The Fernhill SCADA OPC Classic Server supports these OPC AE Interfaces:
Using these interfaces, an OPC AE client applications can browse, query, and acknowledge alarms.
To learn about other Fernhill SCADA Concepts.
To learn about the tool to configure Fernhill SCADA.
To learn about the different drivers available in Fernhill SCADA.
To learn about the SCADA Server.
To learn about integrating data into third party applications.
For the meaning of terms used in Fernhill SCADA.