System Status Viwer Aspect - Status Not Available
800xA 5.1 rev. D
Redundant AS, CS (AC800M), CS(3rd party OPC)
Verified no abb services were interrupted or undefined
Verfied no 800xA system hardware or service alarms were present that could be related to this issue
Verified network connectivity of servers through RNRP (both network connections up for each of the servers.)
We have PG2 graphics created for each of the 14 controllers in our system. The PG2 graphic contains an aspect view wrapper which allows us to display the "System Status Viewer" aspect.
Recently we noticed the the status indications displayed on these graphics cyclically go from green (Good) to Red (Status not available) and back to green (good) for the hardware that is being displayed in the "System Status Viewer" aspect. The period of this status cycling is roughly 1-2 minutes. Note these graphics have generally taken considerably more time to load relative other process graphics which do not use the aspect view wrapper.
We have performed several tests to try to get a better understanding of what may be causing this.
- Compared two HMIs displaying the same graphic displays. Each of the HMIs show approximately the same thing with slight latency differences. In some case there will be large differences in the number of bad vs good status.
- Compared two HMIs displaying the same graphic displays. Once bad status was appearing on both, one HMI was left untouched, and the other HMI was forced manually to refresh the graphic. The result was the once left untrouched remained bad status while the other which was forced to refresh showed mostly good status for the hardware elements in the system status viewer aspect.
- Evaluated the process data for a controller showing bad system status viewer status. The data quality on the process graphic appeared to be unaffected and the data continues to update.
-To be certain this wasn't a single controller issue we monitored several controller's system status viewer aspects. Each one displayed the same bad status at roughly the same time noting a message status not available.
Any thoughts on what could be causing this problem?
Should I be concerned about process data quality?
The System Status Viewer, SSV aspect is very resource intensive. The SSV will upon being called, subscribe to the S_xxx (system status) properties from *all* descendant objects relatively from where the SSV was called.
There is no summary status available, meaning that the subscription will need to iterate each and every "leaf object" and perform the synchronous OPC calls AddGroup, AddItems, etc.
The amount of effort required by the various OPC servers involved to service these requests is substantial. The update rate of AC 800M hardware status OPC items is 5000 ms (probably set to a slow value with intention) compared to 1000 ms for regular process related properties.
Due to the SSV's nature of using Property Translations aspects as a middle layer between the reporting unit and the system status collector the performance is less than if there had been a dedicated PG2 displays built. No OPC subscription caching is possible as with regular process graphics. On the other hand, it is very easy to implement system status - just add a property translation from what you have into the SSV's S_xxx properties, add a SSV aspect and you are set.
- Due to its nature, I advise against embedding SSVs into regular process graphics
- I advise against calling top level SSVs in large installations - use it on a lower level
The "very tiny" example above makes use of 28(!) OPC groups for AC 800M hardware. In large installations, the number of individual OPC groups easily reach the hundreds or worse...
The SSV depend on the OPC server to deliver data with "Good" quality.
If the OPC server does not return "Good", the Property Translations will automatically be set with "Bad" and the SSV will indicate "*Unable to get System Status data*". Hence, verify that source (leaf) item deliver good OPC quality - if not, consider filing a support case with your regional ABB support center.