概念
Variable Status Alarms
The variable status alarm monitors the status of a variable. The alarm is triggered when the value of the monitored variable is either forced, overridden or offline. If you configure the alarm to trigger on all statuses, the alarm is triggered immediately when the variable changes to one of the statuses.
The override status indicates that the value of a variable is adjusted by the I/O hardware, and is not the measured value. 有关更多信息，请参阅 Output Override Status .
The force status indicates that the value of a variable is adjusted by the software, and is not the measured value. 有关更多信息，请参阅 强制和取消强制按钮 .
The offline status indicates that the status of the monitored variable is offline.
For example, you can use the variable status alarm to get a notification when a technician overrides the variable on an I/O module.
You can configure the variable status alarms using shunt variable and time delay. 有关更多信息，请参阅 Alarm Functions .
The Value at change column, in the Alarms pane or Alarm View, displays the value of the monitored variable when the alarm changed state. For a variable status alarm, the Value at change column displays the status of the monitored variable:
(Blank: Neither forced, overridden, nor offline)
Forced
Overridden
Offline
Any combination of forced, overridden, and offline
Alarm Types
Alarms Overview
Alarm Functions
Variable Status Alarm Properties – Basic Tab
Creating a Variable Status Alarm
Alarms Pane and Alarm View Customization