The multistate alarm extension adds the alarming capability for an attribute with True or False, or Multistate data types, such as the Present Value of a Binary Input Object.
The multistate alarm extension detects the alarm with respect to a difference from a defined normal state and sets the Alarm State attribute of the object to which it is added. In addition, you can configure the multistate alarm extension to report alarms and True or False and/or Multistate events.