UA-.NETStandard/samples/Scales/README.md

OPC 40200 Scales samples

Two console applications show the Opc.Ua.Scales* libraries end to end:

• a server that publishes weighing equipment with the fluent builders;
• a client that discovers the scales, drives them and streams their weights and notifications with ScalesClient.

Sample	What it does
ScalesServer	Serves a packing line and four stand-alone scales, and simulates them twice a second
ScalesClient	Discovers every scale, prints each one, drives the checkweigher, then streams its weights, events and alarms

The Scales developer guide explains every API used here.

Run

In two terminals:

dotnet run --project samples/Scales/ScalesServer -- --port 62548
dotnet run --project samples/Scales/ScalesClient -- --insecure --seconds 20

Client options:

• --insecure makes the client accept the server's self-signed certificate. Never use it in production.
• --url <endpoint> sets the server endpoint. The default is opc.tcp://localhost:62548/ScalesServer.
• --seconds <n> sets how long to stream. 0 skips streaming.

The client prints something like:

Scale system PackingLine1 (Contoso Weighing PL-0001), PackML Idle

Checkweigher1 - Checkweigher scale
  Contoso Weighing CW-600, serial CW-0100
  range 0 .. 0.6, d = 0.0001, e = 0.0002
  current    gross 0.5057 kg, net 0.5057, tare 0 (None_0)
  registered gross 0.5089 kg, net 0.5089, tare 0 (None_0)
  products   CEREAL-500 (Cereal 500 g), CEREAL-375 (Cereal 375 g); in processing: CEREAL-500
  PackML     Idle

AnalyticalBalance - Laboratory scale
  Contoso Lab XP-220, serial AB-220
  range 0 .. 0.22, d = 1E-07, e = 1E-06
  current    gross 0.1 kg, net 0.1, tare 0 (None_0)
  registered none yet
…

Driving Checkweigher1:
  SetTare: done
  ClearTare: done
  registered gross 0.4968 kg, net 0.4968, tare 0 (None_0)
  RegisterWeight: done
  SwitchProduct CEREAL-375: done
  current products: CEREAL-375

Streaming weights and notifications of Checkweigher1 for 20 s ...
  weight gross 0.5062, net 0.5062, tare 0 (None_0)
  ALARM 401 Component: The labeler is out of labels.
  event 103 Process: Package of 0.4846 kg rejected.
  cleared 401 Component: Labels restocked.
  …

NodeIds and namespace indices are whatever the server assigned. Only the browse names are stable.

What the server shows

File	Shows
Program.cs	AddScales() and ConfigureScales(...) on the generic host
PackingLine.cs	The equipment, listed below
ScaleSimulation.cs	A BackgroundService publishing loads through the scale handles, listed below

The equipment in PackingLine.cs:

• Scale system. CreateScaleSystemAsync builds a system with PackML and production output.
• Checkweigher. It has products that are locked, selectable and manageable, plus an infeed feeder with a speed range and a labeler.
• Laboratory balance. The sample sets its legal-for-trade model flag through WithLegalForTrade() and accepts kg, g and mg. This simulated configuration is not regulatory approval for a weighing instrument.
• Counting scale. A piece-counting scale with a selected product.
• Weighbridge. A vehicle scale whose VehicleInformationProvider answers GetVehicleInformation.
• Batching scale. A recipe scale with a two-branch BREAD recipe and a RecipeFileHandler for uploaded recipe files.

What the simulation does:

• Rejects about one package in ten below T1, with a BAD_PACK event and a rejected count.
• Runs the labeler out of labels every 20 s, raising and clearing a PRINTER_FAULT alarm.
• Drives the laboratory balance, the counting scale and a truck crossing the weighbridge.

Runtime updates. The simulation calls PublishLoad and the controller methods on the handles it kept at configuration time. Every call publishes its changes, so subscribed clients see each update without further code.

What the client shows

Code in Program.cs	Shows
connection.Session.Scales(telemetry)	Creating the client; registers the OPC 40200 structured types
scales.IsSupported	Detecting whether the server publishes OPC 40200
DiscoverScalesAsync, EnumerateSystemScalesAsync	Discovery from the DI DeviceSet and Machinery Machines, then the scales of a system
ReadSnapshotAsync → ScaleSnapshot	A whole scale in one pass
ReadPackMLStateAsync	The innermost active PackML state
SetTareAsync, ClearTareAsync, RegisterWeightAsync, SwitchProductAsync	Driving a scale that sits inside a scale system
ObserveWeightAsync, ObserveNotificationsAsync	Streaming weights, events and alarms of that nested scale

SampleSession.cs sets up the session. It keeps the ApplicationInstance alive until the session closes, because the instance owns the CertificateManager the session validates with.

Publish as NativeAOT

Both samples are NativeAOT-compatible on net10.0:

dotnet publish samples/Scales/ScalesServer -c Release -f net10.0 -r osx-arm64

Troubleshooting

Symptom	Fix
Client reports BadCertificateUntrusted	Pass --insecure for the demo, or trust the server certificate in the client's PKI
The server publishes no scales.	Wait for the server log line Materialised scale 'BatchingScale' before starting the client
Port already in use	Another server (often an earlier sample run) holds it. Stop it, or start the server with --port <n> and the client with --url opc.tcp://localhost:<n>/ScalesServer
No events or alarms while streaming	Stream for at least 20 s. Rejects are random and the labeler runs out every 20 s