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TwinCAT follow-up — Symbol browser via AdsClient + SymbolLoaderFactory. Closes task #188. Adds ITwinCATClient.BrowseSymbolsAsync — IAsyncEnumerable yielding TwinCATDiscoveredSymbol (InstancePath + mapped TwinCATDataType + ReadOnly flag) from the target's flat symbol table. AdsTwinCATClient implementation uses SymbolLoaderFactory.Create(_client, new SymbolLoaderSettings(SymbolsLoadMode.Flat)) + iterates loader.Symbols, maps IEC 61131-3 type names (BOOL/SINT/INT/DINT/LINT/REAL/LREAL/STRING/WSTRING/TIME/DATE/DT/TOD + BYTE/WORD/DWORD/LWORD unsigned-word aliases) through MapSymbolTypeName, checks SymbolAccessRights.Write bit for writable vs read-only. Unsupported types (UDTs / function blocks / arrays / pointers) surface with DataType=null so callers can skip or recurse. TwinCATDriverOptions.EnableControllerBrowse — new bool, default false to preserve the strict-config path. When true, DiscoverAsync iterates each device's BrowseSymbolsAsync, filters via TwinCATSystemSymbolFilter (rejects TwinCAT_*, Constants.*, Mc_*, __*, Global_Version* prefixes + anything empty), skips null-DataType symbols, emits surviving symbols under a per-device Discovered/ sub-folder with InstancePath as both FullName + BrowseName + ReadOnly→ViewOnly/writable→Operate. Pre-declared tags from TwinCATDriverOptions.Tags always emit regardless. Browse failure is non-fatal — exception caught + swallowed, pre-declared tags stay in the address space, operators see the failure in driver health on next read. TwinCATSystemSymbolFilter static class mirrors AbCipSystemTagFilter's shape with TwinCAT-specific prefixes. Fake client updated — BrowseResults list for test setup + FireNotification-style single-invocation on each subscribe, ThrowOnBrowse flag for failure testing. 8 new unit tests — strict path emits only pre-declared when EnableControllerBrowse=false, browse enabled adds Discovered/ folder, filter rejects system prefixes, null-DataType symbols skipped, ReadOnly symbols surface ViewOnly, browse failure leaves pre-declared intact, SystemSymbolFilter theory (10 cases). Total TwinCAT unit tests now 110/110 passing (+17 from the native-notification merge's 93); full solution builds 0 errors; other drivers untouched.

Browse Source 
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Joseph Doherty
2026-04-19 20:13:33 -04:00
parent 9ca80fd450
commit c95228391d
7 changed files with 385 additions and 2 deletions
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54
src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/AdsTwinCATClient.cs
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@@ -1,5 +1,9 @@
using System.Collections.Concurrent;
using System.Runtime.CompilerServices;
using TwinCAT;
using TwinCAT.Ads;
using TwinCAT.Ads.TypeSystem;
using TwinCAT.TypeSystem;
namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
@@ -149,6 +153,56 @@ internal sealed class AdsTwinCATClient : ITwinCATClient
catch { /* best-effort tear-down; target may already be gone */ }
}
public async IAsyncEnumerable<TwinCATDiscoveredSymbol> BrowseSymbolsAsync(
[EnumeratorCancellation] CancellationToken cancellationToken)
{
// SymbolLoaderFactory downloads the symbol-info blob once then iterates locally — the
// async surface on this interface is for our callers, not for the underlying call which
// is effectively sync on top of the already-open AdsClient.
var settings = new SymbolLoaderSettings(SymbolsLoadMode.Flat);
var loader = SymbolLoaderFactory.Create(_client, settings);
await Task.Yield(); // honors the async surface; pragmatic given the loader itself is sync
foreach (ISymbol symbol in loader.Symbols)
{
if (cancellationToken.IsCancellationRequested) yield break;
var mapped = MapSymbolTypeName(symbol.DataType?.Name);
var readOnly = !IsSymbolWritable(symbol);
yield return new TwinCATDiscoveredSymbol(symbol.InstancePath, mapped, readOnly);
}
}
private static TwinCATDataType? MapSymbolTypeName(string? typeName) => typeName switch
{
"BOOL" or "BIT" => TwinCATDataType.Bool,
"SINT" or "BYTE" => TwinCATDataType.SInt,
"USINT" => TwinCATDataType.USInt,
"INT" or "WORD" => TwinCATDataType.Int,
"UINT" => TwinCATDataType.UInt,
"DINT" or "DWORD" => TwinCATDataType.DInt,
"UDINT" => TwinCATDataType.UDInt,
"LINT" or "LWORD" => TwinCATDataType.LInt,
"ULINT" => TwinCATDataType.ULInt,
"REAL" => TwinCATDataType.Real,
"LREAL" => TwinCATDataType.LReal,
"STRING" => TwinCATDataType.String,
"WSTRING" => TwinCATDataType.WString,
"TIME" => TwinCATDataType.Time,
"DATE" => TwinCATDataType.Date,
"DT" or "DATE_AND_TIME" => TwinCATDataType.DateTime,
"TOD" or "TIME_OF_DAY" => TwinCATDataType.TimeOfDay,
_ => null, // UDTs / FB instances / arrays / pointers — out of atomic scope
};
private static bool IsSymbolWritable(ISymbol symbol)
{
// SymbolAccessRights is a flags enum — the Write bit indicates a writable symbol.
// When the symbol implementation doesn't surface it, assume writable + let the PLC
// return AccessDenied at write time.
if (symbol is Symbol s) return (s.AccessRights & SymbolAccessRights.Write) != 0;
return true;
}
public void Dispose()
{
_client.AdsNotificationEx -= OnAdsNotificationEx;

22
src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/ITwinCATClient.cs
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@@ -66,11 +66,33 @@ public interface ITwinCATClient : IDisposable
TimeSpan cycleTime,
Action<string, object?> onChange,
CancellationToken cancellationToken);
/// <summary>
/// Walk the target's symbol table via the TwinCAT <c>SymbolLoaderFactory</c> (flat mode).
/// Yields each top-level symbol the PLC exposes — global variables, program-scope locals,
/// function-block instance fields. Filters for our atomic type surface; structured /
/// UDT / function-block typed symbols surface with <c>DataType = null</c> so callers can
/// decide whether to drill in via their own walker.
/// </summary>
IAsyncEnumerable<TwinCATDiscoveredSymbol> BrowseSymbolsAsync(CancellationToken cancellationToken);
}
/// <summary>Opaque handle for a registered ADS notification. <see cref="IDisposable.Dispose"/> tears it down.</summary>
public interface ITwinCATNotificationHandle : IDisposable { }
/// <summary>
/// One symbol yielded by <see cref="ITwinCATClient.BrowseSymbolsAsync"/> — full instance
/// path + detected <see cref="TwinCATDataType"/> + read-only flag.
/// </summary>
/// <param name="InstancePath">Full dotted symbol path (e.g. <c>MAIN.bStart</c>, <c>GVL.Counter</c>).</param>
/// <param name="DataType">Mapped <see cref="TwinCATDataType"/>; <c>null</c> when the symbol's type
/// doesn't map onto our supported atomic surface (UDTs, pointers, function blocks).</param>
/// <param name="ReadOnly"><c>true</c> when the symbol's AccessRights flag forbids writes.</param>
public sealed record TwinCATDiscoveredSymbol(
string InstancePath,
TwinCATDataType? DataType,
bool ReadOnly);
/// <summary>Factory for <see cref="ITwinCATClient"/>s. One client per device.</summary>
public interface ITwinCATClientFactory
{

40
src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDriver.cs
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@@ -217,7 +217,7 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
// ---- ITagDiscovery ----
public Task DiscoverAsync(IAddressSpaceBuilder builder, CancellationToken cancellationToken)
public async Task DiscoverAsync(IAddressSpaceBuilder builder, CancellationToken cancellationToken)
{
ArgumentNullException.ThrowIfNull(builder);
var root = builder.Folder("TwinCAT", "TwinCAT");
@@ -225,6 +225,8 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
{
var label = device.DeviceName ?? device.HostAddress;
var deviceFolder = root.Folder(device.HostAddress, label);
// Pre-declared tags — always emitted as the authoritative config path.
var tagsForDevice = _options.Tags.Where(t =>
string.Equals(t.DeviceHostAddress, device.HostAddress, StringComparison.OrdinalIgnoreCase));
foreach (var tag in tagsForDevice)
@@ -241,8 +243,42 @@ public sealed class TwinCATDriver : IDriver, IReadable, IWritable, ITagDiscovery
IsAlarm: false,
WriteIdempotent: tag.WriteIdempotent));
}
// Controller-side symbol browse — opt-in. Falls back to pre-declared-only on any
// client-side error so a flaky symbol-table download doesn't block discovery.
if (_options.EnableControllerBrowse && _devices.TryGetValue(device.HostAddress, out var state))
{
IAddressSpaceBuilder? discoveredFolder = null;
try
{
var client = await EnsureConnectedAsync(state, cancellationToken).ConfigureAwait(false);
await foreach (var sym in client.BrowseSymbolsAsync(cancellationToken).ConfigureAwait(false))
{
if (TwinCATSystemSymbolFilter.IsSystemSymbol(sym.InstancePath)) continue;
if (sym.DataType is not TwinCATDataType dt) continue; // unsupported type
discoveredFolder ??= deviceFolder.Folder("Discovered", "Discovered");
discoveredFolder.Variable(sym.InstancePath, sym.InstancePath, new DriverAttributeInfo(
FullName: sym.InstancePath,
DriverDataType: dt.ToDriverDataType(),
IsArray: false,
ArrayDim: null,
SecurityClass: sym.ReadOnly
? SecurityClassification.ViewOnly
: SecurityClassification.Operate,
IsHistorized: false,
IsAlarm: false,
WriteIdempotent: false));
}
}
catch (OperationCanceledException) { throw; }
catch
{
// Symbol-loader failure is non-fatal to discovery — pre-declared tags already
// shipped + operators see the failure in driver health on next read.
}
}
}
return Task.CompletedTask;
}
// ---- ISubscribable (native ADS notifications with poll fallback) ----

9
src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDriverOptions.cs
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@@ -23,6 +23,15 @@ public sealed class TwinCATDriverOptions
/// notification limits you can't raise.
/// </summary>
public bool UseNativeNotifications { get; init; } = true;
/// <summary>
/// When <c>true</c>, <c>DiscoverAsync</c> walks each device's symbol table via the
/// TwinCAT <c>SymbolLoaderFactory</c> (flat mode) + surfaces controller-resident
/// globals / program locals under a <c>Discovered/</c> sub-folder. Pre-declared tags
/// from <see cref="Tags"/> always emit regardless. Default <c>false</c> to preserve
/// the strict-config path for deployments where only declared tags should appear.
/// </summary>
public bool EnableControllerBrowse { get; init; }
}
/// <summary>

32
src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATSystemSymbolFilter.cs Normal file
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@@ -0,0 +1,32 @@
namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
/// <summary>
/// Filter system / infrastructure symbols out of a TwinCAT symbol-loader walk. TC PLC
/// runtimes export plumbing symbols alongside user-declared ones — <c>TwinCAT_SystemInfoVarList</c>,
/// constants, IO task images, motion-layer internals — that clutter an OPC UA address space
/// if exposed.
/// </summary>
public static class TwinCATSystemSymbolFilter
{
/// <summary><c>true</c> when the symbol path matches a known system / infrastructure prefix.</summary>
public static bool IsSystemSymbol(string instancePath)
{
if (string.IsNullOrWhiteSpace(instancePath)) return true;
// Runtime-exported info lists.
if (instancePath.StartsWith("TwinCAT_SystemInfoVarList", StringComparison.OrdinalIgnoreCase)) return true;
if (instancePath.StartsWith("TwinCAT_", StringComparison.OrdinalIgnoreCase)) return true;
if (instancePath.StartsWith("Global_Version", StringComparison.OrdinalIgnoreCase)) return true;
// Constants pool — read-only, no operator value.
if (instancePath.StartsWith("Constants.", StringComparison.OrdinalIgnoreCase)) return true;
// Anonymous / compiler-generated.
if (instancePath.StartsWith("__", StringComparison.Ordinal)) return true;
// Motion / NC internals routinely surfaced by the symbol loader.
if (instancePath.StartsWith("Mc_", StringComparison.OrdinalIgnoreCase)) return true;
return false;
}
}