- I1: the poll engine belongs to a teardown generation. ShutdownAsync/Dispose
retire the current engine and install a fresh one in the same swap as the
device/tag tables, then dispose the retired one (possibly in the background
after a cancelled or over-budget shutdown). A subscription made after the
next InitializeAsync can no longer land in an engine whose late dispose tail
would dispose its CTS without cancelling it (a loop no UnsubscribeAsync could
find). Poll handles are generation-qualified (TwinCATPollHandle) because each
engine numbers handles from 1; SubscribeAsync re-homes a subscription that
raced a retirement.
- M1: a write's status feeds per-device health - Good clears that device's
comms fault and advances LastSuccessfulRead, a comms status degrades, a
refusal keeps the state.
- M2: a symbol-version re-arm bumps a per-registration epoch; an in-flight
retry that fails afterwards no longer re-imposes the backoff.
- M3: a re-arm restarts the refusal backoff at 30 s.
- M4: documented that PLC-not-in-RUN detection needs the probe.
- M5: WSTRING and multi-dimensional array encode-plan tests; the cancelled-
shutdown test asserts Unknown health and awaits its background teardown.
- M6: an infinity spelled as a string ('Infinity', '-inf') passes like a
float/double infinity; a finite overflow stays BadOutOfRange.
Refs #739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
- IMPORTANT: a successful probe records the PLC's ADS state; a PLC not in Run
keeps the driver Degraded with 'PLC in {state}' while LastSuccessfulRead
still advances (the device answered). RecordDeviceAnswered never restores
Healthy while any device is out of Run.
- Health is per device, rolled up worst-of: a comms fault is remembered on the
device it was seen on and only that device answering clears it (device A
answering no longer clears device B's fault).
- Refused (non-comms) dead registrations back off 30 s doubling to 10 min and
are re-armed by a symbol-version change or retried by the reconnect replay;
comms-class failures keep the every-tick retry. A retry whose failure class
changes republishes the tag's status, once.
- Bit-RMW gates are kept across generations and teardowns (never cleared).
- ShutdownAsync honours its CancellationToken: it stops waiting, finishes the
bookkeeping and throws OperationCanceledException.
- Remarks on why a superseded InitializeAsync throws OperationCanceledException.
- REAL / LREAL values (scalar or array element) outside the target range are
OverflowException -> BadOutOfRange instead of being written as Infinity.
- String / array write encoding factored into AdsTwinCATClient.PlanStringWrite
/ PlanArrayWrite; the fake runs them so a driver-level test covers the real
encode path against a fake resolved symbol.
- Timing-fragile tests use condition waits / measured probe-tick windows; the
dispose-during-shutdown test asserts ordering with a 1 s bound.
Refs #739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
- Device and tag tables are build-and-swap: InitializeAsync builds a fresh
generation and publishes it by one swap under a lifecycle lock, then
releases the replaced generation; teardown swaps in empty tables. A
retained poll loop never sees a table mid-Clear (it used to read
_tagsByRawPath while a re-init only ever added to it), and each device
set is released by exactly one caller.
- A lifecycle generation makes an InitializeAsync overtaken by a shutdown
(or a newer init) release what it built instead of installing it - the
Lane A abandoned-init-overlaps-shutdown case.
- ShutdownAsync joins all probe loops together within 2 s (it awaited each
unbounded - a probe wedged in the blocking ADS Connect hung the actor's
teardown) in parallel with the poll-engine dispose, the whole bounded at
4.5 s; DisposeAsync may run concurrently and returns at once. A connect
that completes on a released device disposes its client.
- Releasing a generation disposes its native registrations, so a direct
re-init no longer leaves live notifications bound to dead DeviceStates.
- Connect gates and RMW semaphores are no longer disposed under in-flight
users (no kernel handle is ever allocated); a fault on a released device
is not recorded as driver health.
- The notification channel counts DropWrite overflows
(ITwinCATClient.DroppedNotificationCount); the probe tick warns with the
delta. A queued value whose registration was disposed is purged in the
client dispatch loop and dropped driver-side for any client.
Refs #739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Array tags were advertised writable but every write threw InvalidCastException
in ConvertForWrite (reported BadTypeMismatch); STRING writes went through the
Beckhoff marshaller with no length check against STRING(n) and the host's
ANSI code page, which the read side deliberately avoids.
- Array write: TwinCATArrayCodec.ToWriteElements converts exactly ArrayLength
elements to the declared type (CLR lists convert - ScadaBridge writes int[]
to Int16 nodes; a length mismatch or out-of-range element is BadOutOfRange, a
scalar value BadTypeMismatch) before any wire traffic; the ADS client plans
the layout from the resolved PLC array (TwinCATTypeGuard.CheckArray, as the
read does), encodes with TwinCATArrayCodec.Encode - the exact inverse of
Decode - and writes the raw bytes (new ITwinCATClient.WriteArrayAsync).
- STRING / WSTRING write: encoded at the PLC's declared width by
TwinCATStringCodec.EncodeString/EncodeWString (Windows-1252 or UTF-8 per
target, NUL-padded, strict: an over-long value or unrepresentable character
is OverflowException -> BadOutOfRange) and written as raw bytes.
- TwinCAT CLI read/write gain --array-length (+ --separator) for the hardware
gate.
Refs #739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The bit write read and wrote the parent word as a 32-bit UDInt with no parent
check: a bit beyond a 16-bit parent was written into neighbouring bytes, and a
signed parent with its sign bit set read back >= 2^31, so the checked
conversion turned any bit write into BadOutOfRange.
The write now goes through ITwinCATClient.WriteBitAsync: the ADS client
resolves the parent symbol, checks the bit against it (TwinCATBitAccess.
CheckParent, as the notification path already did), reads exactly
parent.ByteSize raw bytes, flips one bit (TwinCATBitAccess.ApplyBitWrite) and
writes the bytes back by index group/offset or variable handle. A bit beyond
the parent is BadOutOfRange, a non-integer parent BadTypeMismatch, a short
parent read BadCommunicationError (never written back), all without a health
write. The per-parent RMW lock stays in the driver.
Refs #739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Strict width+kind eligibility for sum-batched scalars (others read singly); latch only on ADS
1793/1794, split 1792/1797/1798 without latching; 32 KiB per-command budget and 500-item ceiling;
short sum response handled per item. Diagnostics: opt-in diagnosticsEnabled (default off), reuse the
probe's ReadState, sample after the host-state transition, JitterMs renamed HeadroomMs, compact
per-device line so many devices fit the 16-entry cap, unavailable-symbol latch cleared on reconnect.
AdminUI: min/max on sum-read max, diagnostics checkbox. Pure planner extracted and unit-tested.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
Sum-read (#310): batches a poll's reads per device into sum commands capped at sumReadMaxItems,
per-item ADS errors mapped per tag, falls back to individual reads when the target refuses the
command. Diagnostics (#314): ADS state, app name, online-change count, task cycle/exec/jitter via
IDriverDiagnostics. Re-implemented against the current raw-byte read path (stranded auto/driver-gaps
commits predate it). Sum-write not ported. Unit tests only; live gate pending a route.
Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
An array tag subscribed natively used to register only its declared scalar
(publishing element 0 at Good) and was then refused wholesale with
BadTypeMismatch. The driver now hands the authored ArrayLength to the client,
which registers the whole array as raw bytes and decodes every notification.
- TwinCATTypeGuard.CheckArray plans the layout from the RESOLVED array type:
element checked like a scalar notification (width / float kind / string
kind); STRING(n)/WSTRING(n) elements stride n+1 / 2(n+1); multi-dim arrays
flattened in PLC memory order; an authored ArrayLength shorter than the PLC
array reads the leading sub-range, a longer one is refused; struct / pointer
/ nested-array elements, non-array symbols and VAR_IN_OUT refs are refused.
- CheckNotificationSize caps a native array at 128 KiB (largest registration
proven on a live TC 2.11 target); above it the tag is refused BadOutOfRange.
- TwinCATArrayCodec decodes the bytes into the element-typed CLR array.
- The poll read uses the same plan + codec instead of the Beckhoff typed array
read, which failed live for most real arrays (exact CLR element type, rank-N
for multi-dim, member arrays sliced by the under-reported TC2 symbol size).
- TwinCATNotificationRefusedException carries the refusal's status; the type
mismatch derives from it and the driver isolates either per tag.
Port of the ignitionoee TwinCAT string + type-reconciliation fixes onto the
Beckhoff-library client:
- STRING/WSTRING subscriptions never worked: AddDeviceNotificationExAsync was
called with typeof(string) and no length, and the Beckhoff any-type
marshaller throws ArgumentNullException for a string without one, so one
string tag tore down its whole subscribe call. A string now registers the
PLC's own byte width as raw bytes (0.19.2: STRING(n) of any n).
- Strings are read as raw bytes and decoded by TwinCATStringCodec. The
Beckhoff marshaller already cut a read at the first NUL (0.19.3 / TwinCAT-007
were not defects on the read path); the codec keeps that rule for both STRING
and WSTRING and extends it to the new notification path. A STRING now decodes
as Windows-1252 (TwinCAT-010) - or UTF-8 when the target reports UTF-8
strings - instead of the host culture's ANSI code page the Beckhoff
marshaller falls back to (1250 on a Polish host, 1251 Cyrillic, ...).
- TwinCATTypeGuard (TwinCAT-002/-008): a read refuses a numeric tag over a PLC
string (and vice versa / STRING vs WSTRING / string over a container) with
BadTypeMismatch instead of handing back a string object at Good; a
notification - raw bytes decoded as the DECLARED type - additionally refuses
width and float/integer mismatches (DINT over REAL reinterpreted the bits).
- A refused notification is isolated: that tag publishes BadTypeMismatch with
one WARN, keeps a dead intent for the probe-tick retry, and the rest of the
subscription registers.
Native ADS notifications (the default subscribe mode) were stored as opaque handles
with no record of the symbol/type/interval/handler needed to replay. On a client swap
(EnsureConnectedAsync building a fresh client after a drop) the notifications were
silently orphaned — no Bad status, no error, pushes just stopped until redeploy.
Compounding: the IsConnected fast-path keys on AMS-port state, not wire liveness, and
a probe failure only transitioned state without recycling the dead client.
Fix:
- Store REPLAYABLE INTENT: NativeRegistration (symbol/type/bit/interval/onChange +
swappable live handle) hung off DeviceState.NativeRegistrations, populated by
SubscribeAsync via RegisterNotificationAsync (under ConnectGate).
- Split EnsureConnectedAsync into a gate wrapper + EnsureConnectedUnderGateAsync core;
when the core installs a NEW client it replays every stored intent onto it and swaps
the live handle (disposing the dead one). Register + replay both run under ConnectGate
so they can't race.
- Probe loop: on a wire-probe failure (false or throw) RecycleClientAsync disposes+nulls
the client so the next tick rebuilds + replays — closes the fast-path-keys-on-port-state
compounding bug.
No TwinCAT docker fixture exists (integration needs a real TC3 XAR), so the fake-client
unit tests are the authoritative coverage:
- 4 new guards in TwinCATReconnectReplayTests (replay-onto-fresh-client + push reaches
OnDataChange + old handle disposed; replay-all-tags; unsubscribe-after-reconnect stops
replaying; probe-failure recycles+rebuilds).
- Full TwinCAT unit suite 174/174 green; full solution builds 0 errors.
Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.
- Driver.TwinCAT-004: corrected the IEC time-type inline comments;
documented that the driver currently surfaces them as raw UInt32
counters.
- Driver.TwinCAT-006: ResolveHost returns a documented UnresolvedHost
sentinel when no devices are configured instead of returning the
logical DriverInstanceId (which never matches GetHostStatuses).
- Driver.TwinCAT-014: wired Probe.Timeout into the probe-loop call and
added a NotificationMaxDelayMs config knob threaded through
AddNotificationAsync.
- Driver.TwinCAT-015: Dispose() runs a genuinely synchronous teardown
with bounded waits (no sync-over-async deadlock pattern).
- Driver.TwinCAT-016: pinned the Structure-tag rejection and the
probe-loop vs read disposal race with regression tests.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Driver.TwinCAT-001 — InitializeAsync/ReinitializeAsync ignored driverConfigJson.
Extracted the DTO-to-options parse into a shared TwinCATDriverFactoryExtensions.ParseOptions;
InitializeAsync now re-parses driverConfigJson into a mutable _options field, so a config
generation pushed via ReinitializeAsync (added/removed devices, tags, probe settings) is
actually applied at runtime.
Driver.TwinCAT-002 — LInt/ULInt narrowed to Int32. ToDriverDataType now maps LInt to Int64,
ULInt to UInt64, UDInt to UInt32, UInt/USInt to UInt16, Int/SInt to Int16, and the IEC
TIME/DATE/DT/TOD types to UInt32 (their raw UDINT counter). Removed the stale "Int64 gap"
comment — no truncation or sign flips at the OPC UA encode layer.
Driver.TwinCAT-007 — EnsureConnectedAsync was not thread-safe. Connect/reconnect is now
serialized per device by a SemaphoreSlim (DeviceState.ConnectGate) with a double-checked
connect, mirroring the S7 driver. Concurrent read/write/probe callers can no longer leak a
client or race a create-vs-dispose.
Driver.TwinCAT-008 — native ADS notification callbacks ran driver logic on the AMS router
thread. AdsTwinCATClient now enqueues AdsNotificationEx callbacks onto a bounded Channel
drained by a dedicated managed task; the router-thread callback only does a non-blocking
TryWrite, so a slow consumer cannot stall ADS notification delivery process-wide.
Driver.TwinCAT-013 — TwinCATDriver did not implement IRediscoverable. The driver now
implements IRediscoverable; AdsTwinCATClient detects ADS 0x0702 (symbol-version-changed) on
read/write paths and raises OnSymbolVersionChanged, which the driver forwards as
OnRediscoveryNeeded so Core rebuilds the address space after a PLC program re-download.
Adds TwinCATHighFindingsRegressionTests covering all five fixes; updates the data-type
mapping assertion in TwinCATDriverTests. TwinCAT driver builds clean; 119 tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.
- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
integration, install).
Build green (0 errors); unit tests pass. Docs left for a separate pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty