dohertj2/lmxopcua
1
0
Fork 0
Code Issues 14 Pull Requests Actions Packages Projects Releases Wiki Activity

docs(historian): design §9.10 — comms-loss IS historized as an outage marker (T3 review correction)

Browse Source 
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
This commit is contained in:
Joseph Doherty
2026-10-09 12:51:34 -04:00
parent ff7c6c531a
commit 9973ae08be
1 changed files with 1 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
docs/plans/2026-10-09-pluggable-historian-design.md
+1 -1
View File
@@ -344,5 +344,5 @@ These were verified against the code and override anything above that conflicts.
7. **Processed reads** are capped at 100 000 buckets per request.
8. **HistoryUpdate admission.** The `HistoryWrite` AccessLevel bit decides whether the SDK base admits a node to HistoryUpdate at all, so the updater must be wired before any node materialises. `OtOpcUaServerHostedService.StartAsync` assigns it (via the new `OtOpcUaSdkServer.SetHistorianDataUpdater`) before `SetSink`. Nodes materialised earlier keep their AccessLevel (no retro-update).
9. **HistoryUpdate results.** Successful arms set `errors[i] = Good`. A `SourceTimestamp == DateTime.MinValue` is `BadInvalidTimestamp`.
10. **Comms-loss is not historized.** Watchdog `BadNoCommunication` stamps are node-only and never reach the mux, so they are not historized. A driver's own Bad publish is, usually with a null value, so it is stored as `Empty` kind with the driver's Bad code (Modbus `0x80050000`).
10. **Comms-loss IS historized, as an outage marker** (corrected after the T3 review). `DriverHostActor.FanCommsLossToDependencyMux` (#481) sends `null` + `BadNoCommunication` for every value ref to the mux, so the recorder receives it, and it cannot be told apart from a driver's own Bad publish. On a backend whose `SupportedKinds` include `Empty` (SQL Server), each disconnect stores one `Empty`/`BadNoCommunication` sample per historized tag. This is deliberate: it records the gap, so raw reads show the outage and aggregates and interpolation do not bridge it. On a numeric-only backend (Gateway) it is dropped as an unsupported kind and counted in `DroppedUnsupportedKind`. A driver's own Bad publish is handled the same way (`Empty` kind plus its Bad code, e.g. Modbus `0x80050000`).
11. **Parallel safety.** `SqlServerTagCatalog` belongs to the skeleton task (T8), so the parallel SQL tasks share one.