BadQuality Event confusion
The BadQuality Event does not appear in the system. I use it to see if connection with OPC Server lost.
As I understand it depends on Soft Alarms service. It's in service state, no errors.
For Alarm Expression I choose Process Alarm for Soft Alarms and added it to my Alarm list Configuration.
I would be greatful for any ideas!
Voted best answer
The SoftAlarm service, will if enabled, issue bad quality alarms on alarm expressions where one or more input properties receive bad quality.
Hence, for an alarm to be raised:
- An alarm expression must be exposed to bad quality
- Bad quality alarm must be enabled on the SoftAlarm Service (see users guides)
I believe an alternate mechanism would be to use a Property Transfer. The PT can be set with a substitute value which will be used if input becomes bad.
Here are some more details you asked for.
A PG2 display can read OPC quality using #DataQuality, #QualityDetail and #QualityDescription sub properties.
By connecting the #DataQuality subproperty to the DataQuality property of e.g. a PG2 Text element you enable bad data quality presentation (see red cross below)
(I'm using the Matrikon OPC Simulator to create "bad" quality values)
To trigger an arbitrary alarm, you could use Property Transfer to transfer the "suspect" property over to another OPC item (another controller e.g. or to a General Property) and use the Substitute value to send a key value (e.g. 999) if bad quality is observed on the input.
The PT configuration is below and in the upper picture (above) you can see how the value of the property transfer assume "999". This value can then be used to trigger an alarm expression or an PLC alarm (if you configure the PT to write to a controller property)