Joseph Doherty
c81cef39f5
Layer 4 of the condition-Quality chain (#477 -> #478). #478 gave a scripted condition the worst quality of its input tags, but only for inputs whose driver PUBLISHES a Bad data change. A poll driver whose device goes unreachable publishes nothing — it raises ConnectivityChanged(false) and goes silent — so the engine held its last Good value, WorstInputStatus stayed Good, and worse, AreInputsReady stayed true, so the predicate went on evaluating a stale value after the source had died. `DriverHostActor.FanCommsLossToDependencyMux` pushes a synthetic BadNoCommunication with a null value into the dependency mux for every value ref the disconnected driver owns. The issue asked for a driver -> all-tag-refs map to be built for this. It already exists: `_nodeIdByDriverRef`, keyed (DriverInstanceId, RawPath) and rebuilt from the composition on every apply. Alarm-bearing tags live in the separate `_alarmNodeIdByDriverRef` and are deliberately excluded — a native condition is not a mux value and takes the Part 9 quality path instead. Nothing is pushed on reconnect, deliberately: publishing Good would assert a value quality this actor has not observed. Recovery rides the driver's own republish, and the mechanism was verified rather than assumed — the Connected -> Reconnecting edge calls DetachSubscription, which nulls the subscription handle, so the reconnect's ResubscribeDesired builds a FRESH subscription whose PollGroupEngine initial push runs with forceRaise: true. Without that detach the poll engine would compare against its retained LastValues, see an unchanged value, raise nothing, and strand these refs Bad forever — the value-dedup trap that bit the v3 Batch 4 virtual-tag reassert. Closes #478 Finding 3, which the above depends on. WorstInputStatus skipped every input whose VALUE was null as "no data yet" — and Bad-with-no-value is exactly the shape a comms-lost driver produces, so the skip was hiding the case that matters most; without this half the fan-out above would be silently inert. The upstream source now stamps a never-pushed path BadWaitingForInitialData — the honest Part 4 code for that state — and the engine skips that specific code rather than every null value. Deleting the null-skip outright is the obvious fix and is wrong in the other direction: it makes every not-yet-published input drag its condition Bad at deploy, flooding the quality path with load-time annotations, which is what the skip existed to prevent. Both mistakes are pinned by a test pair that goes red under the opposite error, and both were falsified by reverting the production code: old null-skip restored -> A_pushed_Bad_carrying_no_value RED null-skip deleted outright -> An_input_that_was_never_pushed RED fan-out call removed -> the three DriverHostActor tests RED (1 of 7) The never-pushed test was vacuous on first writing and is worth recording: the quality bucket only emits on CHANGE, so the load-time evaluation is the one that flashes Bad, and subscribing to OnEvent after LoadAsync made the assertion unfalsifiable — it passed against the broken behaviour. It now subscribes first. `FakeUpstream.ReadTag` returned 0x80340000 (BadNotConnected) for an unset path, a different Bad code from production's placeholder. Harmless while any Bad behaved alike; load-bearing now, so it is aligned and pinned by a reflection guard asserting the engine's private constant agrees with what the production source stamps. Behaviour change to weigh, flagged in the issue and confirmed: virtual tags computed from a comms-lost input now go Bad too. That follows from using the shared mux and reads as correct, but it is broader than scripted alarms. Claude-Session: https://claude.ai/code/session_015p7wGqy3YpZNCpDzTpGMKo
OtOpcUa
OPC UA server (.NET 10 AnyCPU) that exposes a fleet of industrial drivers as a single OPC UA address space. Drivers ship in-process for AVEVA System Platform Galaxy (via the sibling mxaccessgw repo), Modbus TCP, Siemens S7, Allen-Bradley CIP (ControlLogix / CompactLogix), Allen-Bradley Legacy (SLC 500 / MicroLogix), Beckhoff TwinCAT (ADS), FANUC FOCAS, OPC UA Client (gateway), and MQTT (broker subscribe; Sparkplug B in progress).
A cross-platform client stack (.NET 10) — shared library, CLI, and Avalonia desktop app — connects to any OPC UA server.
Architecture
OPC UA Clients (CLI, Desktop UI, 3rd-party)
|
v
+-------------------------------------+
| OtOpcUa.Server (.NET 10 AnyCPU) |
| address space + capability fan-out|
+-------------------------------------+
| | | | | | | |
Galaxy Modbus S7 AbCip AbLeg TwinCAT FOCAS OpcUaClient MQTT
|
v
mxaccessgw (sibling repo, gRPC)
|
v
MXAccess COM (x86 worker, on AVEVA box)
Galaxy is the only driver with an external runtime: it speaks gRPC to a separately installed mxaccessgw server (sibling repo at c:\Users\dohertj2\Desktop\mxaccessgw\) which owns the MXAccess COM apartment and the x86/STA bitness constraint server-side. Everything in this repo is platform-agnostic .NET 10.
Prerequisites
- .NET 10 SDK (server, drivers, clients all target .NET 10)
- SQL Server reachable for the central config DB
- For Galaxy specifically: a running
mxaccessgwdeployment — see docs/v2/Galaxy.ParityRig.md - For historian read-back / alarm history / continuous historization: a running
ZB.MOM.WW.HistorianGatewaydeployment (the sole historian backend; consumed as theZB.MOM.WW.HistorianGateway.ClientgRPC package). It must runRuntimeDb:Enabled=true+RuntimeDb:EventReadsEnabled=true, and the API key must carryhistorian:read+historian:write+historian:tags:writescopes.
Quick Start
dotnet restore ZB.MOM.WW.OtOpcUa.slnx
dotnet build ZB.MOM.WW.OtOpcUa.slnx
dotnet test ZB.MOM.WW.OtOpcUa.slnx
# Run the server in dev (foreground)
dotnet run --project src/Server/ZB.MOM.WW.OtOpcUa.Host
The server starts on opc.tcp://localhost:4840 with the None security profile. Configure Security.Profiles in src/Server/ZB.MOM.WW.OtOpcUa.Host/appsettings.json to enable Basic256Sha256-Sign or Basic256Sha256-SignAndEncrypt. See docs/security.md.
Install as Windows Services
Production deployment is driven by scripts/install/Install-Services.ps1, which registers the OtOpcUa server service under a chosen service account. Historian support requires a separately deployed ZB.MOM.WW.HistorianGateway and Galaxy support a separately installed mxaccessgw — neither this repo nor the install script provisions them.
.\scripts\install\Install-Services.ps1 `
-InstallRoot 'C:\Program Files\OtOpcUa' `
-ServiceAccount 'DOMAIN\svc-otopcua'
The historian backend is the external ZB.MOM.WW.HistorianGateway (not installed by this script). See the script header and docs/ServiceHosting.md for full options.
Client CLI
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- connect -u opc.tcp://localhost:4840
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- browse -u opc.tcp://localhost:4840 -r -d 3
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- read -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode"
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- write -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode" -v 42
dotnet run --project src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI -- subscribe -u opc.tcp://localhost:4840 -n "ns=2;s=SomeNode" -i 500
See docs/Client.CLI.md and docs/Client.UI.md.
Documentation
Architecture deep-dives
| Topic | Doc |
|---|---|
| OPC UA server composition, namespace fan-out, Polly invoker | docs/OpcUaServer.md |
| Address space layout | docs/AddressSpace.md |
| Read / Write dispatch (driver vs virtual vs scripted-alarm) | docs/ReadWriteOperations.md |
| Incremental sync (driver-backend rediscovery + config publishes) | docs/IncrementalSync.md |
| Service hosting (Server + Admin; external HistorianGateway backend) | docs/ServiceHosting.md |
| Security (transport, LDAP, certificates) | docs/security.md |
| Redundancy | docs/Redundancy.md |
| Status dashboard | docs/StatusDashboard.md |
Drivers
| Topic | Doc |
|---|---|
| Driver specs (per-driver capability surface, config, addressing) | docs/v2/driver-specs.md |
| Galaxy driver | docs/drivers/Galaxy.md |
| Modbus / S7 / AbCip / AbLegacy / TwinCAT / FOCAS / OpcUaClient / MQTT | docs/drivers/ |
| Galaxy parity rig (mxaccessgw setup) | docs/v2/Galaxy.ParityRig.md |
| Galaxy performance + tracing | docs/v2/Galaxy.Performance.md |
Clients
| Topic | Doc |
|---|---|
| Client CLI | docs/Client.CLI.md |
| Client UI (Avalonia desktop) | docs/Client.UI.md |
v1 archive
The original v1 in-process MXAccess docs (Galaxy.Host topology, Configuration env vars, AlarmTracking, DataTypeMapping, HistoricalDataAccess, Subscriptions, etc.) are preserved under docs/v1/ — historical reference only. PR 7.2 retired the v1 architecture on 2026-04-30; current state is documented in the sections above.
License
Internal use only.