Review round 1 on the golden frames:
- Re-captured logix-read-dint-array16 (element i = ((i+1)<<24)|(i+1)) and
logix-read-bool (= 1) so neither decode oracle is all zeros. ab_server rejects
libplctag's own BOOL write with CIP 0x03 (two data bytes for a one-byte BOOL),
so the BOOL is seeded by a raw UCMM Write Tag (client seed-bool).
- Committed the capture client as scripts/ab-capture/client (outside the slnx,
CPM off, libplctag 1.5.2 pinned); capture.sh gains a `client` subcommand.
- README documents simulator-only behaviour: zeroed reply sender context, STRING
typed D0 00 instead of A0 02 + handle, and the BOOL write refusal.
- capture.sh no longer claims UnregisterSession reaches the wire (session ends in RST).
- CaptureFileTests also check the CPF walk ends at the frame end and that every
reply service is its request service | 0x80.
17 .hex fixtures captured from libplctag 1.5.2 (native 2.6.0) against
otopcua-ab-server:libplctag-release, plus the CaptureFile loader, its
length/alternation tests, and the re-runnable scripts/ab-capture/capture.sh.
Observed and recorded in Captures/README.md "Routing observed":
- Micro800 is NOT UCMM under libplctag 2.6.0: it opens a Large Forward Open
(path 20 02 24 01) and reads connected; use_connected_msg=0 is ignored.
- SLC500/MicroLogix/PLC-5 send Execute PCCC 0x4B unconnected and unwrapped;
a configured path=1,0 never reaches the wire.
- Only Large FO 0x5B was observed; no 0x54 fallback occurred.
- LogixPccc is unreachable against ab_server (CIP 0x08); no fixture committed.
Found by the read-only live gate against the TwinCAT 2.11 Elma cleaners
Z33856 / Z33733:
- The Beckhoff library reports a TC2 dotted MEMBER symbol's ByteSize as if the
PLC's byte count were a bit count (STRING(80) -> 11, INT -> 1, UDINT -> 1)
while DataType.ByteSize is right (81/2/4, raw SYM_INFOBYNAMEEX says 81). The
previous commit's typeof(byte[]) read sliced by the symbol size, so
.OPC_MACHINEDATA.PROCESSSTATUS read "ready for o" at Good; the notification
width check would also have refused every numeric member. The shape now takes
the resolved type's size, and string reads go by index group/offset (or a
fresh handle for 0xF005) at that width.
- P_INITINPUT_ACTION.SLOTID is "STRING(20) (VAR_IN_OUT)" - a 4-byte reference -
but resolves to a plain STRING(20); a String tag read 21 bytes at the pointer
as text at Good. The symbol's own VAR_IN_OUT marker now classifies it
NonScalar -> BadTypeMismatch.
libplctag decodes whatever bytes the controller returns as the authored type and never
checks the CIP type code. Live read-only check on a production press: WW_ActualVacuum is a
REAL (L5X + the controller's symbol table agree) but the legacy Kepware export in the
ignitionoee repo types it Short; read as INT it returned Good -17346 while the real value
was 5.37. A scalar atomic read (not an array, not a bit-in-DINT) whose buffer size is not
the authored type's width now reads BadTypeMismatch with a warning naming both. Widths
observed live: SINT/BOOL 1, INT 2, DINT/REAL 4, LINT 8. IAbCipTagRuntime.GetSize() is a
default-interface member (-1 = unknown, never checked). Same-width mismatches (DINT vs
REAL) stay undetectable without the type code libplctag strips.
The mock had served the shapes the driver once agreed with it on, so it
validated the very defects just fixed: it ANSWERED the non-existent 0x00D3
cnc_getfigure, wrote base/exponent 0/0 into position blocks, put the macro
decimal at offset 4, and served spindle 'max rpm' as a raw constant.
Ported from the sister ignitionoee mock (local divergence recorded in
VENDORED.md; the LE timer and alarm cap are kept):
- 0x00D3 refused with EW_FUNC, as the real control does.
- 0x0026 blocks carry base 10 / position_figures exponent; signed arg2,
arg2 = 0 or past the axis count refused EW_ATTRIB.
- cnc_rdmacro is the 8-byte ODBM shape, 9-digit mantissa, unset = vacant.
- servo/spindle meter records carry the envelope; spindle meters are
1/16384-of-full-scale counts (motor speed = speed / max_rpm).
Integration tests: spindle test reads Load/MotorSpeedPct percentages; the
position-scale test now proves the block's own scale wins; new
Vacant_positions_and_macros_read_bad_over_the_wire. 12/12 pass against the
mock run locally (python -m focas_mock.cli serve, OTOPCUA_FOCAS_SIM_ENDPOINT).
Live read-only check against a production CompactLogix press: Program:UN01_Press._ModeNames
(STR0016[32], 4 elements requested) returned an 80-byte buffer with libplctag.NET 1.5.2's
ElementSize unset. The driver fell back to the static 88-byte STRING stride, read element
1 past the buffer, and the whole read failed (ErrorOutOfBounds -> BadCommunicationError).
When the buffer divides evenly by the element count, that quotient is now the stride;
the read returns [undefined, Production, Maintenance, Manual] as the controller holds.
Live read-only check against a production CompactLogix press: with one nonexistent tag
first in the read list, libplctag's create threw LibPlcTagException("ErrorNotFound"); the
driver counted it as a failed Forward-Open, opened the device's 05/STAB-8 connect-backoff
window, and every other cold tag on the device - all real (WW_InCycle, WW_ActualPress,
WW_WorkOrderNum) - read BadCommunicationError. In steady polling the bad tag re-opens
the window each attempt, so siblings ordered after it may never connect.
- A create that fails with a "controller answered" status (NotFound/NoMatch/BadDevice,
the probe's existing reachable classification) records backoff SUCCESS, not failure.
Genuine connection failures still open the window (falsification control test).
- Read exceptions map through the libplctag Status they carry: unknown tag ->
BadNodeIdUnknown, decode past the buffer -> BadOutOfRange, timeout -> BadTimeout,
instead of a blanket BadCommunicationError. One status-name parser
(AbCipStatusMapper.TryGetStatus) now serves both the read path and the probe.
WireFocasClient.GetProgramInfoAsync defaulted every field the CNC did not report:
ONumber ?? 0 when the cnc_exeprgname2 payload was too short to carry it, and
Name '' / BlockCount 0 / Mode 0 when the sub-read was refused. 0 is a genuine
O-number (a 31i reports 0 for a path-executed program -- live Z-34184), a
genuine block count, and Mode 0 is MDI, a real operating mode.
FocasProgramInfo fields are now nullable; MapProgramInfo leaves unreported
fields null and the fixed tree publishes them BadNoData while the bundle's
other fields stay Good.
Ported from the sister ignitionoee FOCAS driver (101a3b1, 2026-08-12).
Live read-only check: a production CompactLogix lists the module tag ABB_OmniCore:I in
@tags and libplctag reads ABB_OmniCore:I.ConnectionFaulted without complaint, but the
driver refused the path as malformed (identifier rule had no colon) and reported the
tag BadCommunicationError. Colon-separated identifier/slot parts are now legal in the
controller-scope base segment only (never past it, never under Program: scope).
Servo (0x0056) and spindle (0x0040) meter records are 8 bytes:
[i32 value][u16 base][u16 exponent], the same self-describing envelope as the
position blocks.
Servo: offset 4 was read as a decimal count. It is the BASE (a steady 10), so
every load was divided by 10^10 and published ~0 -- the sister ignitionoee panel
read servo 0% on every axis of a Makino cutting at 20,000 rpm. Loads are now
value / base^exponent, a direct percentage.
Spindle: the raw meter is a 1/16384 fraction of full scale. Settled on the real
Z-34184 by regressing the type-1 meter against cnc_rddynamic2 spindle speed over
596..20,000 rpm (rpm = 1.220749 x meter; 16384 x 1.220749 = 20000.75). So:
- Spindle/{name}/Load publishes % of rated load (Float64; was the raw Int32
count -- a reading of 9155 meant 55.9%).
- Spindle/{name}/MaxRpm is RENAMED Spindle/{name}/MotorSpeedPct (Float64, % of
maximum speed) and is polled with Load. The old node was actively wrong: the
type-1 meter is the live motor speed, and it was read once at bootstrap and
served forever as if it were a max-RPM constant. Client-visible: FIXED: tags
on .../MaxRpm must be re-pointed.
- The spindle read no longer stops at the first zero after slot 1 (which dropped
an idle second spindle and kept non-zero residue); every slot is returned.
A record whose envelope is undescribable (base not 2/10, exponent > 18 -- e.g.
residue past the configured axis/spindle count) publishes BadNoData, never a Good 0.
Ported from the sister ignitionoee FOCAS driver v0.17.2/v0.17.3 (Focas.Wire-019);
live captures live-spmeter-{load,maxrpm}-0x0040.bin added as fixtures.
Live read-only check against production CompactLogix 5069-L320ERS2 presses:
- The controller @tags listing names each program (Program:UN01_Press, a system symbol)
but none of its tags; those are listed only by Program:<name>.@tags. The enumerator read
@tags alone, so every program-scoped tag was unbrowseable — including the PackML state
(Program:UN01_Press.Out_eState) and all 51 alarm bits the Ignition project reads. The
enumerator now reads each program's listing and decodes it with that program as scope;
an unreadable program listing is skipped, not fatal.
- The Symbol Object decoder ignored the dimension bits + dim words, so every discovered
array (DINT[32], REAL[32], STRING[50], UDT[23] on the two controllers checked) browsed as
a scalar. IsArray/ElementCount are now populated (multi-dim flattened). A 1-D single
element entry stays scalar: ab_server reports every scalar that way, a real controller
sets no dimension bits on scalars.
Pinned by entries captured off the controllers (CipSymbolObjectRealControllerCaptureTests,
AbCipProgramScopeEnumerationTests).
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.
Live read-only check against production CompactLogix 5069-L320ERS2 rev 34.11 presses
(Z-35162 / 10.209.70.160): every @udt/<id> template the controller returned decoded to
null, so controller-discovered UDTs never fanned out. The decoder assumed a 12-byte
header led by the member count and [info][array][offset] blocks with ';'-terminated
names; libplctag actually returns a 14-byte header (u16 id, u32 def words, u32 instance
size, u16 member count, u16 handle), [info][type][offset] blocks, and NUL-terminated
names after a 'Name;<tail>' type name. All three test builders restated the old
assumption, so the unit suite agreed with itself (the #468 trap again); they now share a
TemplateBufferBuilder pinned by real captures (CipTemplateObjectWireCaptureTests).
Discovery follow-ons that the working decoder exposed:
- STRING (and user string types, LEN DINT + DATA SINT[n]) browse as one String variable,
top-level and nested, not as a LEN/DATA folder.
- Controller-generated members (ZZZZZZZZZZ* BOOL hosts, __* AOI backing) are not browsed.
- A UDT array is not fanned out into element-free Tag.Member paths.
Every 0x0026 position block is self-describing: [i32 raw][u16 base][u16 exponent],
value = raw / base^exponent. The live 31i-B capture (ref-dynamic2-axis1.bin)
reports base 10 / exponent 4 on every block, so axis 1 is 280.1574 mm, not
2801574. The driver ignored the envelope and instead sent 'cnc_getfigure'
(0x00D3) -- a command that does not exist in the FOCAS wire protocol, served only
by the in-tree mock; the real control refuses it with rc=1, so on hardware every
position fell back to PositionDecimalPlaces (default 0) and published raw counts.
- ParsePositionBlock decodes the envelope into FocasPosition; the driver applies
raw / base^exponent at publish. PositionDecimalPlaces is now only the fallback
for a scale-less (4-byte) block.
- A block describing no position (0xFFFF vacant marker, base not 2/10, exponent
> 18 -- raw / 10^400 would read as a Good 0.0) publishes BadNoData on that node
alone; siblings are untouched.
- ReadPositionFiguresAsync / IFocasClient.GetPositionFiguresAsync and the
per-axis figure cache are deleted.
Ported from the sister ignitionoee FOCAS driver v0.17.0 (+ Focas.Wire-014);
live axis-scoped captures live-dynamic2-axis{1,2}-0x0026.bin (Z-34184 X 0.0374,
Y 370.177) added as fixtures.
A TC2 PLC reports top-level integer globals as INT16/UINT16 (354 symbols on
the Elma cleaner Z33856) and the Beckhoff type system keeps that spelling as
a built-in primitive, so MapSymbolTypeName returned null and discovery dropped
them silently. INT16/UINT16/INT32/UINT32/UINT8/FLOAT/DOUBLE now map like their
IEC twins; padded member names ("REAL ") are trimmed; a parenthesised
non-string form ("INT (VAR_IN_OUT)", a reference) stays unsupported.
ReadNameRecord read only the first 2 bytes of each 4-byte 0x0089/0x008A record,
so the real 31i-B's paired axes 'AA6'/'AA7' (live capture ref-axisname-0x0089.bin)
both decoded as 'AA' -- the 'Makino with two AA axes' that #548 then had to
disambiguate as AA_1/AA_2. The name is now the record's ASCII up to its FIRST
NUL (not trailing-NUL trimming), so buffer residue such as Z-34184's spindle
record 53 31 00 4e ('S1' + an 'N' left from an earlier 'CNC') is discarded.
Client-visible: on such a machine Axes/AA_1 and Axes/AA_2 become Axes/AA6 and
Axes/AA7 (the old names were a decode artefact). #548's disambiguation stays as
the guard for genuinely duplicate names.
Ported from the sister ignitionoee FOCAS driver (Focas.Wire-001, Focas.Wire-022
/ v0.18.1).
A TC2 global is named with ONE leading dot (.OPC_HEARTBEAT) and the PLC
requires it (SYM_HNDBYNAME answers 0x710 without it). TryParse rejected the
dot, so the driver fell back to the raw string and lost bit-index parsing:
.X.WORD.3 went to ADS verbatim instead of reading .X.WORD and extracting bit 3.
The dot now stays on the root segment and round-trips through ToAdsSymbolName;
.., ., .[1] and .9x stay invalid.
The ODBM wire payload is [i32 mantissa][i16 length, a constant 10][i16 dec_val].
ReadMacroAsync read the decimal at offset 4, so every macro decoded without
failing but wrongly: the captured #500 = 1.0 (05 f5 e1 00 00 0a 00 08) published
0.01. FANUC normalises macros to a 9-significant-digit mantissa, so the error
was never small.
- dec_val is read at [6..7]; a payload < 8 bytes is refused, not guessed at.
- A vacant variable (dec_val 0xFFFF) publishes BadNoData, never a Good 0.
- Integer-typed tags get the exact whole value (integer arithmetic); a
fractional macro on an integer tag is BadTypeMismatch, a whole value that
does not fit the type BadOutOfRange. Float tags get mantissa / 10^dec.
Ported from the sister ignitionoee FOCAS driver v0.15.0 (Focas.Wire-013,
Focas-017/018); live vectors from Makino Z-34184 (31i-B, G431).
Adds a WireFixtures helper that loads the raw 31i-B captures in Fixtures/v3.
Joseph Doherty