There are some details about equipment that need to be shown in the alarms using the alarms table. These are 2 properties s_Equipment_Number & s_Name. Both are of type string.
The Alarm is configured in the UDT type definition and the Label property has an expression binding that combines the details from the above to tags. Please the attached pic for details.
This set up works and the alarms trigger correctly with the data showing correctly in the Label field in the alarm status table. BUT, sometimes randomly the data from the properties disappears in the label text & the label appears like this,
“SV : Disabled Alarm - Cannot be utilized for automation”
Instead of, “SV 2281 : Bulk liquid valve Disabled Alarm - Cannot be utilized for automation”
I have verified that the necessary data is still populated in the properties and there are no overrides.
The problem continues to persist until one of the following is done:
- Alarms disables & enables (when alarm is reset forcing the alarm to removed and re-generated). This works some times.
- Alarm Display Path binding is changed to mimic Label binding. Then disables/enable alarm. Both bindings evaluate correctly and then Display path binding can be removed and Label binding evaluation stays with the correct value.
We cannot use Display Path as its being used to filter alarms and we would like to use Label property for better HMI description of Alarms.
Any idea what is incorrect here and if there is an issue with Label expression binding, is there a work around?