Block a user
dohertj2
created branch twincat-native-notifications in dohertj2/lmxopcua
2026-04-19 18:51:23 -04:00
aeb28cc8e7
TwinCAT PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Completes the TwinCAT driver — 7-interface capability set matching AbCip / AbLegacy (minus IAlarmSource, same deferral). ITagDiscovery emits pre-declared tags under TwinCAT/device-host folder with DeviceName fallback to HostAddress; Writable→Operate / non-writable→ViewOnly. Symbol-browsing via AdsClient.ReadSymbolsAsync / ReadSymbolInfoAsync deferred to a follow-up (same shape as the @tags deferral for AbCip — needs careful traversal of the TwinCAT symbol table + type graph which the ReadSymbolsAsync API does expose but adds enough scope to warrant its own PR). ISubscribable consumes the shared PollGroupEngine — 4th consumer after Modbus + AbCip + AbLegacy. TwinCAT supports native ADS notifications (AddDeviceNotification) which would be strictly superior to polling, but plumbing through OPC UA semantics + the PollGroupEngine abstraction would require a parallel sampling path; poll-first matches the cross-driver pattern + gets the driver shippable. Follow-up task for native-notification upgrade tracked after merge. IHostConnectivityProbe — per-device probe loop using ITwinCATClient.ProbeAsync which wraps AdsClient.ReadStateAsync (cheap handshake that returns the target's AdsState, succeeds when router + target both respond). Success transitions to Running, any exception or probe-false to Stopped. Same lazy-connect + dispose-on-failure pattern as the read/write path — device state reconnects cleanly after a transient. IPerCallHostResolver maps tag full-ref to DeviceHostAddress for Phase 6.1 (DriverInstanceId, ResolvedHostName) bulkhead/breaker keying per plan decision #144; unknown refs fall back to first device, no devices → DriverInstanceId. ShutdownAsync disposes PollGroupEngine + cancels/disposes every probe CTS + disposes every cached client. DeviceState extended with ProbeLock / HostState / HostStateChangedUtc / ProbeCts matching AbCip/AbLegacy shape. 10 new tests in TwinCATCapabilityTests — discovery tag emission with correct SecurityClassification, subscription initial poll raises OnDataChange, shutdown cancels subscriptions, GetHostStatuses entry-per-device, probe Running transition on ProbeResult=true, probe Stopped on ProbeResult=false, probe disabled when Enabled=false, ResolveHost for known/unknown/no-devices paths. Total TwinCAT unit tests now 85/85 passing (+10 from PR 2's 75); full solution builds 0 errors; other drivers untouched. TwinCAT driver complete end-to-end — any TC2/TC3 AMS target reachable through a router is now shippable with read/write/discover/subscribe/probe/host-resolve, feature-parity with AbCip/AbLegacy.
TwinCAT PR 3 � Discovery + Subscribe + Probe + HostResolver
TwinCAT PR 3 � Discovery + Subscribe + Probe + HostResolver
dohertj2
pushed to twincat-pr3-remaining-capabilities at dohertj2/lmxopcua
2026-04-19 18:38:31 -04:00
aeb28cc8e7
TwinCAT PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Completes the TwinCAT driver — 7-interface capability set matching AbCip / AbLegacy (minus IAlarmSource, same deferral). ITagDiscovery emits pre-declared tags under TwinCAT/device-host folder with DeviceName fallback to HostAddress; Writable→Operate / non-writable→ViewOnly. Symbol-browsing via AdsClient.ReadSymbolsAsync / ReadSymbolInfoAsync deferred to a follow-up (same shape as the @tags deferral for AbCip — needs careful traversal of the TwinCAT symbol table + type graph which the ReadSymbolsAsync API does expose but adds enough scope to warrant its own PR). ISubscribable consumes the shared PollGroupEngine — 4th consumer after Modbus + AbCip + AbLegacy. TwinCAT supports native ADS notifications (AddDeviceNotification) which would be strictly superior to polling, but plumbing through OPC UA semantics + the PollGroupEngine abstraction would require a parallel sampling path; poll-first matches the cross-driver pattern + gets the driver shippable. Follow-up task for native-notification upgrade tracked after merge. IHostConnectivityProbe — per-device probe loop using ITwinCATClient.ProbeAsync which wraps AdsClient.ReadStateAsync (cheap handshake that returns the target's AdsState, succeeds when router + target both respond). Success transitions to Running, any exception or probe-false to Stopped. Same lazy-connect + dispose-on-failure pattern as the read/write path — device state reconnects cleanly after a transient. IPerCallHostResolver maps tag full-ref to DeviceHostAddress for Phase 6.1 (DriverInstanceId, ResolvedHostName) bulkhead/breaker keying per plan decision #144; unknown refs fall back to first device, no devices → DriverInstanceId. ShutdownAsync disposes PollGroupEngine + cancels/disposes every probe CTS + disposes every cached client. DeviceState extended with ProbeLock / HostState / HostStateChangedUtc / ProbeCts matching AbCip/AbLegacy shape. 10 new tests in TwinCATCapabilityTests — discovery tag emission with correct SecurityClassification, subscription initial poll raises OnDataChange, shutdown cancels subscriptions, GetHostStatuses entry-per-device, probe Running transition on ProbeResult=true, probe Stopped on ProbeResult=false, probe disabled when Enabled=false, ResolveHost for known/unknown/no-devices paths. Total TwinCAT unit tests now 85/85 passing (+10 from PR 2's 75); full solution builds 0 errors; other drivers untouched. TwinCAT driver complete end-to-end — any TC2/TC3 AMS target reachable through a router is now shippable with read/write/discover/subscribe/probe/host-resolve, feature-parity with AbCip/AbLegacy.
dohertj2
created branch twincat-pr3-remaining-capabilities in dohertj2/lmxopcua
2026-04-19 18:38:31 -04:00
28e3470300
TwinCAT PR 2 — IReadable + IWritable. ITwinCATClient + ITwinCATClientFactory abstraction — one client per AMS target, reused across reads/writes/probes. Shape differs from AbCip/AbLegacy where libplctag handles are per-tag — TwinCAT's AdsClient is a single connection with symbolic reads/writes issued against it, so the abstraction is coarser. AdsTwinCATClient is the default implementation wrapping Beckhoff.TwinCAT.Ads's AdsClient — ConnectAsync calls AdsClient.Connect(AmsNetId.Parse(netId), port) after setting Timeout in ms; ReadValueAsync dispatches TwinCATDataType to the CLR Type via MapToClrType (bool/sbyte/byte/short/ushort/int/uint/long/ulong/float/double/string/uint for time types) and calls AdsClient.ReadValueAsync(symbol, type, ct) which returns ResultAnyValue; unwraps .Value + .ErrorCode and maps non-NoError codes via TwinCATStatusMapper.MapAdsError. BOOL-within-word reads extract the bit after the underlying word read using ExtractBit over short/ushort/int/uint/long/ulong. WriteValueAsync converts the boxed value via ConvertForWrite (Convert.ToXxx per type) then calls AdsClient.WriteValueAsync returning ResultWrite; checks .ErrorCode for status mapping. BOOL-within-word writes throw NotSupportedException with a pointer to task #181 — same RMW gap as Modbus BitInRegister / AbCip BOOL-in-DINT / AbLegacy bit-within-N-file. ProbeAsync calls AdsClient.ReadStateAsync + checks AdsErrorCode.NoError. TwinCATDriver implements IReadable + IWritable — per-device ITwinCATClient cached in DeviceState.Client, lazy-connected on first read/write via EnsureConnectedAsync, connect-failure path disposes + clears the client so next call re-attempts cleanly. ReadAsync ordered-snapshot pattern matching AbCip/AbLegacy: unknown ref → BadNodeIdUnknown, unknown device → BadNodeIdUnknown, OperationCanceledException rethrow, any other exception → BadCommunicationError + Degraded health. WriteAsync similar — non-Writable tag → BadNotWritable upfront, NotSupportedException → BadNotSupported, FormatException/InvalidCastException (guard pattern) → BadTypeMismatch, OverflowException → BadOutOfRange, generic → BadCommunicationError. Symbol name resolution goes through TwinCATSymbolPath.TryParse(def.SymbolPath) with fallback to the raw def.SymbolPath if the path doesn't parse — the Beckhoff AdsClient handles the final validation at wire time. ShutdownAsync disposes each device's client. 14 new unit tests in TwinCATReadWriteTests using FakeTwinCATClient + FakeTwinCATClientFactory — unknown ref → BadNodeIdUnknown, successful DInt read with Good status + captured value + IsConnected=true after EnsureConnectedAsync, repeat reads reuse the connection (one Connect + multiple reads), ADS error code mapping via FakeTwinCATClient.ReadStatuses, read exception → BadCommunicationError + Degraded health, connect exception disposes the client, batched reads preserve order across DInt/Real/String types, non-Writable rejection, successful write logs symbol+type+value+bit for test inspection, write status-code mapping, write exception → BadCommunicationError, batch preserves order across success/non-writable/unknown, cancellation propagation, ShutdownAsync disposes the client. Total TwinCAT unit tests now 75/75 passing (+14 from PR 1's 61); full solution builds 0 errors; Modbus / AbCip / AbLegacy / other drivers untouched.
TwinCAT PR 2 � IReadable + IWritable
TwinCAT PR 2 � IReadable + IWritable
28e3470300
TwinCAT PR 2 — IReadable + IWritable. ITwinCATClient + ITwinCATClientFactory abstraction — one client per AMS target, reused across reads/writes/probes. Shape differs from AbCip/AbLegacy where libplctag handles are per-tag — TwinCAT's AdsClient is a single connection with symbolic reads/writes issued against it, so the abstraction is coarser. AdsTwinCATClient is the default implementation wrapping Beckhoff.TwinCAT.Ads's AdsClient — ConnectAsync calls AdsClient.Connect(AmsNetId.Parse(netId), port) after setting Timeout in ms; ReadValueAsync dispatches TwinCATDataType to the CLR Type via MapToClrType (bool/sbyte/byte/short/ushort/int/uint/long/ulong/float/double/string/uint for time types) and calls AdsClient.ReadValueAsync(symbol, type, ct) which returns ResultAnyValue; unwraps .Value + .ErrorCode and maps non-NoError codes via TwinCATStatusMapper.MapAdsError. BOOL-within-word reads extract the bit after the underlying word read using ExtractBit over short/ushort/int/uint/long/ulong. WriteValueAsync converts the boxed value via ConvertForWrite (Convert.ToXxx per type) then calls AdsClient.WriteValueAsync returning ResultWrite; checks .ErrorCode for status mapping. BOOL-within-word writes throw NotSupportedException with a pointer to task #181 — same RMW gap as Modbus BitInRegister / AbCip BOOL-in-DINT / AbLegacy bit-within-N-file. ProbeAsync calls AdsClient.ReadStateAsync + checks AdsErrorCode.NoError. TwinCATDriver implements IReadable + IWritable — per-device ITwinCATClient cached in DeviceState.Client, lazy-connected on first read/write via EnsureConnectedAsync, connect-failure path disposes + clears the client so next call re-attempts cleanly. ReadAsync ordered-snapshot pattern matching AbCip/AbLegacy: unknown ref → BadNodeIdUnknown, unknown device → BadNodeIdUnknown, OperationCanceledException rethrow, any other exception → BadCommunicationError + Degraded health. WriteAsync similar — non-Writable tag → BadNotWritable upfront, NotSupportedException → BadNotSupported, FormatException/InvalidCastException (guard pattern) → BadTypeMismatch, OverflowException → BadOutOfRange, generic → BadCommunicationError. Symbol name resolution goes through TwinCATSymbolPath.TryParse(def.SymbolPath) with fallback to the raw def.SymbolPath if the path doesn't parse — the Beckhoff AdsClient handles the final validation at wire time. ShutdownAsync disposes each device's client. 14 new unit tests in TwinCATReadWriteTests using FakeTwinCATClient + FakeTwinCATClientFactory — unknown ref → BadNodeIdUnknown, successful DInt read with Good status + captured value + IsConnected=true after EnsureConnectedAsync, repeat reads reuse the connection (one Connect + multiple reads), ADS error code mapping via FakeTwinCATClient.ReadStatuses, read exception → BadCommunicationError + Degraded health, connect exception disposes the client, batched reads preserve order across DInt/Real/String types, non-Writable rejection, successful write logs symbol+type+value+bit for test inspection, write status-code mapping, write exception → BadCommunicationError, batch preserves order across success/non-writable/unknown, cancellation propagation, ShutdownAsync disposes the client. Total TwinCAT unit tests now 75/75 passing (+14 from PR 1's 61); full solution builds 0 errors; Modbus / AbCip / AbLegacy / other drivers untouched.
cd2c0bcadd
TwinCAT PR 1 — Scaffolding + Core (TwinCATDriver + AMS address + symbolic path). New Driver.TwinCAT project referencing Beckhoff.TwinCAT.Ads 7.0.172 (the official Beckhoff .NET client — 1.6M+ downloads, actively maintained by Beckhoff + community). Package compiles without a local AMS router; wire calls need a running router (TwinCAT XAR on dev Windows, or the standalone Beckhoff.TwinCAT.Ads.TcpRouter embedded package for headless/CI). Same Core.Abstractions-only project shape as Modbus / AbCip / AbLegacy. TwinCATAmsAddress parses ads://{netId}:{port} canonical form — NetId is 6 dot-separated octets (NOT an IP; AMS router translates), port defaults to 851 (TC3 PLC runtime 1). Validates octet range 0-255 and port 1-65535. Case-insensitive scheme. Default-port stripping in canonical form for roundtrip stability. Rejects wrong scheme, missing //, 5-or-7-octet NetId, out-of-range octets/ports, non-numeric fragments. TwinCATSymbolPath handles IEC 61131-3 symbolic names — single-segment (Counter), POU.variable (MAIN.bStart), GVL.variable (GVL.Counter), structured member access (Motor1.Status.Running), array subscripts (Data[5]), multi-dim arrays (Matrix[1,2]), bit-access (Flags.3, GVL.Status.7), combined scope/member/subscript/bit (MAIN.Motors[0].Status.5). Roundtrip-safe ToAdsSymbolName produces the exact string AdsClient.ReadValue consumes. Rejects leading/trailing dots, space in idents, digit-prefix idents, empty/negative/non-numeric subscripts, unbalanced brackets. Underscore-prefix idents accepted per IEC. TwinCATDataType — BOOL / SINT / USINT / INT / UINT / DINT / UDINT / LINT / ULINT / REAL / LREAL / STRING / WSTRING (UTF-16) / TIME / DATE / DateTime (DT) / TimeOfDay (TOD) / Structure. Wider than Logix's surface — IEC adds WSTRING + TIME/DATE/DT/TOD variants. ToDriverDataType widens unsigned + 64-bit to Int32 matching the Modbus/AbCip/AbLegacy Int64-gap convention. TwinCATStatusMapper — Good / BadInternalError / BadNodeIdUnknown / BadNotWritable / BadOutOfRange / BadNotSupported / BadDeviceFailure / BadCommunicationError / BadTimeout / BadTypeMismatch. MapAdsError covers the ADS error codes a driver actually encounters — 6/7 port unreachable, 1792 service not supported, 1793/1794 invalid index group/offset, 1798 symbol not found (→ BadNodeIdUnknown), 1807 invalid state, 1808 access denied (→ BadNotWritable), 1811/1812 size mismatch (→ BadOutOfRange), 1861 sync timeout, unknown → BadCommunicationError. TwinCATDriverOptions + TwinCATDeviceOptions + TwinCATTagDefinition + TwinCATProbeOptions — one instance supports N AMS targets, Tags cross-key by HostAddress, Probe defaults to 5s interval (unlike AbLegacy there's no default probe address — ADS probe reads AmsRouterState not a user tag, so probe address is implicit). TwinCATDriver IDriver skeleton — InitializeAsync parses each device HostAddress + fails fast on malformed strings → Faulted. 61 new unit tests across 3 files — TwinCATAmsAddressTests (6 valid shapes + 12 invalid shapes + 2 ToString canonicalisation + roundtrip stability), TwinCATSymbolPathTests (9 valid shapes + 12 invalid shapes + underscore prefix + 8-case roundtrip), TwinCATDriverTests (DriverType + multi-device init + malformed-address fault + shutdown + reinit + data-type mapping theory + ADS error-code theory). Total project count 30 src + 19 tests; full solution builds 0 errors; Modbus / AbCip / AbLegacy / other drivers untouched.
TwinCAT PR 1 � Scaffolding + Core
TwinCAT PR 1 � Scaffolding + Core
cd2c0bcadd
TwinCAT PR 1 — Scaffolding + Core (TwinCATDriver + AMS address + symbolic path). New Driver.TwinCAT project referencing Beckhoff.TwinCAT.Ads 7.0.172 (the official Beckhoff .NET client — 1.6M+ downloads, actively maintained by Beckhoff + community). Package compiles without a local AMS router; wire calls need a running router (TwinCAT XAR on dev Windows, or the standalone Beckhoff.TwinCAT.Ads.TcpRouter embedded package for headless/CI). Same Core.Abstractions-only project shape as Modbus / AbCip / AbLegacy. TwinCATAmsAddress parses ads://{netId}:{port} canonical form — NetId is 6 dot-separated octets (NOT an IP; AMS router translates), port defaults to 851 (TC3 PLC runtime 1). Validates octet range 0-255 and port 1-65535. Case-insensitive scheme. Default-port stripping in canonical form for roundtrip stability. Rejects wrong scheme, missing //, 5-or-7-octet NetId, out-of-range octets/ports, non-numeric fragments. TwinCATSymbolPath handles IEC 61131-3 symbolic names — single-segment (Counter), POU.variable (MAIN.bStart), GVL.variable (GVL.Counter), structured member access (Motor1.Status.Running), array subscripts (Data[5]), multi-dim arrays (Matrix[1,2]), bit-access (Flags.3, GVL.Status.7), combined scope/member/subscript/bit (MAIN.Motors[0].Status.5). Roundtrip-safe ToAdsSymbolName produces the exact string AdsClient.ReadValue consumes. Rejects leading/trailing dots, space in idents, digit-prefix idents, empty/negative/non-numeric subscripts, unbalanced brackets. Underscore-prefix idents accepted per IEC. TwinCATDataType — BOOL / SINT / USINT / INT / UINT / DINT / UDINT / LINT / ULINT / REAL / LREAL / STRING / WSTRING (UTF-16) / TIME / DATE / DateTime (DT) / TimeOfDay (TOD) / Structure. Wider than Logix's surface — IEC adds WSTRING + TIME/DATE/DT/TOD variants. ToDriverDataType widens unsigned + 64-bit to Int32 matching the Modbus/AbCip/AbLegacy Int64-gap convention. TwinCATStatusMapper — Good / BadInternalError / BadNodeIdUnknown / BadNotWritable / BadOutOfRange / BadNotSupported / BadDeviceFailure / BadCommunicationError / BadTimeout / BadTypeMismatch. MapAdsError covers the ADS error codes a driver actually encounters — 6/7 port unreachable, 1792 service not supported, 1793/1794 invalid index group/offset, 1798 symbol not found (→ BadNodeIdUnknown), 1807 invalid state, 1808 access denied (→ BadNotWritable), 1811/1812 size mismatch (→ BadOutOfRange), 1861 sync timeout, unknown → BadCommunicationError. TwinCATDriverOptions + TwinCATDeviceOptions + TwinCATTagDefinition + TwinCATProbeOptions — one instance supports N AMS targets, Tags cross-key by HostAddress, Probe defaults to 5s interval (unlike AbLegacy there's no default probe address — ADS probe reads AmsRouterState not a user tag, so probe address is implicit). TwinCATDriver IDriver skeleton — InitializeAsync parses each device HostAddress + fails fast on malformed strings → Faulted. 61 new unit tests across 3 files — TwinCATAmsAddressTests (6 valid shapes + 12 invalid shapes + 2 ToString canonicalisation + roundtrip stability), TwinCATSymbolPathTests (9 valid shapes + 12 invalid shapes + underscore prefix + 8-case roundtrip), TwinCATDriverTests (DriverType + multi-device init + malformed-address fault + shutdown + reinit + data-type mapping theory + ADS error-code theory). Total project count 30 src + 19 tests; full solution builds 0 errors; Modbus / AbCip / AbLegacy / other drivers untouched.
400fc6242c
AB Legacy PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Fills out the AbLegacy capability surface — the driver now implements the same 7-interface set as AbCip (IDriver + IReadable + IWritable + ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver). ITagDiscovery emits pre-declared tags under an AbLegacy root folder with a per-device sub-folder keyed on HostAddress (DeviceName fallback to HostAddress when null). Writable tags surface as SecurityClassification.Operate, non-writable as ViewOnly. No controller-side enumeration — PCCC has no @tags equivalent on SLC / MicroLogix / PLC-5 (symbol table isn't exposed the way Logix exposes it), so the pre-declared path is the only discovery mechanism. ISubscribable consumes the shared PollGroupEngine extracted in AB CIP PR 1 — reader delegate points at ReadAsync (already handles lazy runtime init + caching), onChange bridges into the driver's OnDataChange event. 100ms interval floor. Initial-data push on first poll. Makes AbLegacy the third consumer of PollGroupEngine (after Modbus and AbCip). IHostConnectivityProbe — per-device probe loop when ProbeOptions.Enabled + ProbeAddress configured (defaults to S:0 status file word 0). Lazy-init on first tick, re-init on wire failure (destroyed native handle gets recreated rather than silently staying broken). Success transitions device to Running, exception to Stopped, same-state spurious event guard under per-device lock. GetHostStatuses returns one entry per device with current state + last-change timestamp for Admin /hosts surfacing. IPerCallHostResolver maps tag full-ref → DeviceHostAddress for the Phase 6.1 (DriverInstanceId, ResolvedHostName) bulkhead/breaker keying per plan decision #144. Unknown refs fall back to first device's address (invoker handles at capability level as BadNodeIdUnknown); no devices → DriverInstanceId. ShutdownAsync cancels + disposes each probe CTS, disposes PollGroupEngine cancelling active subscriptions, disposes every cached runtime. DeviceState gains ProbeLock / HostState / HostStateChangedUtc / ProbeCts / ProbeInitialized matching AbCip's DeviceState shape. 10 new unit tests in AbLegacyCapabilityTests covering — pre-declared tags emit under AbLegacy/device folder with correct SecurityClassification, subscription initial poll raises OnDataChange with correct value, unsubscribe halts polling (value change post-unsub produces no further events), GetHostStatuses returns one entry per device, probe Running transition on successful read, probe Stopped transition on read exception, probe disabled when ProbeAddress null, ResolveHost returns declared device for known tag, falls back to first device for unknown, falls back to DriverInstanceId when no devices. Total AbLegacy unit tests now 92/92 passing (+10 from PR 2's 82); full solution builds 0 errors; AbCip + Modbus + other drivers untouched. AB Legacy driver now complete end-to-end — SLC 500 / MicroLogix / PLC-5 / LogixPccc all shippable with read / write / discovery / subscribe / probe / host-resolve, feature-parity with AbCip minus IAlarmSource (same deferral per plan).
AB Legacy PR 3 � ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver
AB Legacy PR 3 � ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver
dohertj2
pushed to ablegacy-pr3-remaining-capabilities at dohertj2/lmxopcua
2026-04-19 18:04:27 -04:00
400fc6242c
AB Legacy PR 3 — ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver. Fills out the AbLegacy capability surface — the driver now implements the same 7-interface set as AbCip (IDriver + IReadable + IWritable + ITagDiscovery + ISubscribable + IHostConnectivityProbe + IPerCallHostResolver). ITagDiscovery emits pre-declared tags under an AbLegacy root folder with a per-device sub-folder keyed on HostAddress (DeviceName fallback to HostAddress when null). Writable tags surface as SecurityClassification.Operate, non-writable as ViewOnly. No controller-side enumeration — PCCC has no @tags equivalent on SLC / MicroLogix / PLC-5 (symbol table isn't exposed the way Logix exposes it), so the pre-declared path is the only discovery mechanism. ISubscribable consumes the shared PollGroupEngine extracted in AB CIP PR 1 — reader delegate points at ReadAsync (already handles lazy runtime init + caching), onChange bridges into the driver's OnDataChange event. 100ms interval floor. Initial-data push on first poll. Makes AbLegacy the third consumer of PollGroupEngine (after Modbus and AbCip). IHostConnectivityProbe — per-device probe loop when ProbeOptions.Enabled + ProbeAddress configured (defaults to S:0 status file word 0). Lazy-init on first tick, re-init on wire failure (destroyed native handle gets recreated rather than silently staying broken). Success transitions device to Running, exception to Stopped, same-state spurious event guard under per-device lock. GetHostStatuses returns one entry per device with current state + last-change timestamp for Admin /hosts surfacing. IPerCallHostResolver maps tag full-ref → DeviceHostAddress for the Phase 6.1 (DriverInstanceId, ResolvedHostName) bulkhead/breaker keying per plan decision #144. Unknown refs fall back to first device's address (invoker handles at capability level as BadNodeIdUnknown); no devices → DriverInstanceId. ShutdownAsync cancels + disposes each probe CTS, disposes PollGroupEngine cancelling active subscriptions, disposes every cached runtime. DeviceState gains ProbeLock / HostState / HostStateChangedUtc / ProbeCts / ProbeInitialized matching AbCip's DeviceState shape. 10 new unit tests in AbLegacyCapabilityTests covering — pre-declared tags emit under AbLegacy/device folder with correct SecurityClassification, subscription initial poll raises OnDataChange with correct value, unsubscribe halts polling (value change post-unsub produces no further events), GetHostStatuses returns one entry per device, probe Running transition on successful read, probe Stopped transition on read exception, probe disabled when ProbeAddress null, ResolveHost returns declared device for known tag, falls back to first device for unknown, falls back to DriverInstanceId when no devices. Total AbLegacy unit tests now 92/92 passing (+10 from PR 2's 82); full solution builds 0 errors; AbCip + Modbus + other drivers untouched. AB Legacy driver now complete end-to-end — SLC 500 / MicroLogix / PLC-5 / LogixPccc all shippable with read / write / discovery / subscribe / probe / host-resolve, feature-parity with AbCip minus IAlarmSource (same deferral per plan).