Ignition 8.1.38 Vision
In migrating more towards the High Performance Standard, Sparklines are used quite often in level presentation of tanks. When setting up a Sparkline, whether using Historical or Realtime, is the data always polled from the DB, the Store/Forward, or a realtime buffer (if there is such)? The concern is for operator interaction, what happens if the Historian loses connection? Instantaneous level presentation of a fill bar was always reliant upon the PLC connection. If you lose the PLC comms you have bigger problems. But if a 10 minute sparkline is reliant upon Historian DB queries on a remote SQL box, what happens if that Historian goes down? I suspect the Sparkline disappears, as when configuring a sparkline, I noticed if you choose Natural for data, the sparkline disappears if the data is staler than the length of the trend when configuring it as realtime.
Why in the world would it be a remote SQL box?
Your SCADA's primary database should be on your production LAN with the Ignition gateway. (Also for security, per US Homeland Security recommendations for plant networks.)
If you also need the data offsite, use a streaming replica or a history splitter.
If you absolutely need operator access to such, you should also be using Ignition redundancy and some form of database high availability solution.
Semantics. It is on the same production LAN. But on two different Virtual Servers. Gateway is on one server, the MSSQL is on a different virtual server. But regardless, even if they are on the same box, I'm asking where is the sparkline data retrieved. The whole point of store and forward is for DB connectivity failure. So it happens that connectivity to the DB can be lost. At that time, is the data available to the Sparkline from the local Store/Forward repository?
No, the sparkline data comes from the DB (typically), not from store-and-forward. It is possible to set up in-memory short-term recording, if you must. I even provide a tool for that in my free Integration Toolkit module: recorder()
One quibble:
Note that S&F does nothing for user interfaces. The data it holds is inaccessible until finally delivered to the target DB.
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Thank you sir....that clears it up