Alarm conditions triggered by Boolean (and other discrete data types) often indicate that an analog value has exceeded a limit. In such cases, it can be helpful to have the actual value included in the alarm notification to give it actionable context. 


    Using the example of a tank level that has exceeded its high limit, the alarm type could be evaluated by a bit that is either on or off (1 or 0). 


Tank level is in the normal range = no alarm condition = bit is set to 0

Tank level reaches the configured high limit = alarm condition triggered = bit is set to 1


An alarm message containing the value of "1" may not provide enough detail to an individual in the field. Using Value Substitution, the bit value could be replaced with the actual tank level.


Default: “Tank Level is above the High Limit, Value = 1.”  

Value Substitution: “Tank Level is above the High Limit, Value = 33 feet.”  



    In this example the Item ID is "Tanklevel.inalarm" - a boolean value where "True" indicates an alarm condition and "False" indicates normal. To substitute the analog value, represented by the Item ID of "Tanklevel.pv" - check the Value Substitution checkbox and enter the alternate Item ID in the text entry box, as illustrated below.