lmxopcua/docs/drivers/FOCAS.md

FOCAS Driver

Getting-started guide for the FANUC FOCAS2 driver. This is the short path — for the exhaustive per-node mapping read docs/v2/driver-specs.md §7, for the test-harness map read FOCAS-Test-Fixture.md.

What it talks to

FANUC CNCs (0i-D / 0i-F / 0i-MF / 0i-TF / 16i / 30i / 31i / 32i / Power Motion i) over the proprietary FOCAS2 protocol on TCP port 8193. The wire is spoken directly by the pure-managed Focas.Wire client — no Fwlib64.dll, no P/Invoke, no out-of-process isolation needed.

OtOpcUa is read-only against FOCAS; all reads go over the native wire protocol using the documented command IDs. Writes return BadNotWritable by design.

Equipment tags are forced read-only (R2-11, migration note). The equipment-tag parser (FocasEquipmentTagParser) now hard-codes Writable: false regardless of any authored "writable": true — previously such a tag advertised a writable node whose write always failed at the wire with BadNotWritable; now it fails one step earlier at the driver seam (same family of Bad status, no successful operation changes). The AdminUI FOCAS editor shows the Writable checkbox disabled/unchecked, and the deploy gate warns when a config requests writable:true. Additionally, equipment-tag references now run the same capability-matrix pre-flight authored tags get: a reference whose address violates the device series' matrix fails to resolve (BadNodeIdUnknown) instead of reaching the wire. Honour writable here once PMC writes ship in the wire client.

PDU version (v3 / FANUC 30i/31i). The wire client accepts inbound PDU versions {1, 3} (FocasWireProtocol) while still emitting v1 on requests. Older controls + the docker mock answer v1; modern controls (Makino Pro 5 / FANUC 31i-B) answer v3. Validated live against a real 31i-B (10.201.31.5) 2026-06-25: sysinfo, axis/spindle names, dynamic positions/feed/spindle, program/mode, macros, timers (8-byte payload is little-endian {minute, msec}), PMC range (request widened to the data-type byte width), servo meters (8-byte LOADELM stride + names from the 0x0089 block; load scaling still to be confirmed at commissioning), and alarms all read correctly. The driver cnc_rddynamic2 poll is 1-based. cnc_rdparam is unsupported on this control — every request-framing variant returns EW_FUNC (likely a wrong v3 command id; needs a reference FWLIB trace). The Test-Connect probe now runs a real wire session (initiate + cnc_statinfo) instead of a bare TCP check. Full finding, captured wire bytes, validation results, and analysis: docs/plans/2026-06-25-focas-pdu-v3-30i-b-support.md

• …-implementation-plan.md. Capture tools: scripts/focas/capture-initiate.py, scripts/focas/capture-v3.py.

Project split

Project	Target	Role
src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/	net10.0	In-process driver — hosts WireFocasClient which speaks FOCAS2 over TCP directly

Previous Driver.FOCAS.Host / Driver.FOCAS.Shared Tier-C split has been retired — the managed wire client removes the native-crash blast radius that justified the out-of-process service.

Minimum deployment

Register the driver instance in the main server's appsettings.json. No separate service, no DLL deployment, no shared-secret handshake:

"Drivers": {
  "focas-cnc-1": {
    "Type": "FOCAS",
    "Config": {
      "Backend": "wire",
      "Devices": [
        { "HostAddress": "focas://10.20.30.40:8193", "Series": "ThirtyOne_i" }
      ],
      "Tags": [
        { "Name": "Mode",  "DeviceHostAddress": "focas://10.20.30.40:8193",
          "Address": "PARAM:3402", "DataType": "Int32", "Writable": false },
        { "Name": "SpndLoad", "DeviceHostAddress": "focas://10.20.30.40:8193",
          "Address": "MACRO:500", "DataType": "Float64", "Writable": false }
      ]
    }
  }
}

The main server opens two TCP sockets per configured device and speaks the FOCAS2 binary protocol directly. No local privileged components, no platform bitness constraint — the driver runs on every host OtOpcUa runs on.

Address forms

Form	Example	Meaning
X0.0 / R100 / R100.3	PMC bit or byte	Letter + number; optional .bit for bit access
PARAM:1815 / PARAM:1815/0	CNC parameter	Number + optional axis index
MACRO:500	Custom macro variable	System / user macro variable number
FIXED:Identity/SeriesNumber	Fixed-tree field	A path into the fixed node tree — read-only

The first three name a location the driver asks the CNC for on demand. FIXED: does not: it names a field of the per-device fixed-tree snapshot the driver's own poll loop already maintains, so a FIXED: read issues no wire traffic. It exists because the fixed tree is the only part of the FOCAS surface with no address of its own, and v3 publishes nodes only for authored tags — so without a form to author, the fixed tree could not be published at all.

An address never carries the device. A tag's device comes from its raw-tag Device row; an address that also named a host would be a second, conflicting routing channel. This is worth stating because it is exactly what went wrong in #540: browse leaves advertised {deviceHost}/{path} as their reference, the browse-commit wrote that into the address, and every committed tag read BadNodeIdUnknown forever.

Addresses are validated against the per-device Series at InitializeAsync — a config referencing a number outside the documented range for that series fails at load time with an error message naming the limit. See docs/v2/focas-version-matrix.md for the authoritative range table. (FIXED: paths have no numeric range to check; a path the machine does not expose reads BadNodeIdUnknown.)

An address the parser cannot read is rejected when you author it — by the /raw tag modal, and by the deploy-time inspector for config arriving via CSV import or the API. It is not a warning you can deploy past into a driver that skips the tag at startup.

Backend selection

The driver picks its client from Config.Backend:

Value	Client	Use it for
wire (default)	WireFocasClient	Production — pure-managed FOCAS2 over TCP
unimplemented / none / stub	UnimplementedFocasClientFactory	Scaffolding a DriverInstance row before the CNC endpoint is reachable

Fail-fast on unimplemented / none / stub: a driver instance configured with any of these backends now faults immediately at InitializeAsync with a clear error message rather than reporting healthy and then failing on the first read/write/subscribe. The driver moves to Faulted state and the error is visible on the Admin UI driver-status panel. This is intentional — an operator who forgets to switch to "wire" before deploying to production sees a driver fault at startup, not a phantom-healthy driver that silently rejects every request.

Previous backends (fwlib, fwlib32, ipc) have been retired along with Driver.FOCAS.Host and the Fwlib P/Invoke path. Configs that still reference them will throw at startup with a message pointing here.

Capability surface

Capability	Wire path	Notes
IReadable	ReadAsync → cnc_rdpmcrng / cnc_rdparam / cnc_rdmacro	One TCP request/response per read; Focas.Wire serializes requests on socket 2 internally
IWritable	returns BadNotWritable	OtOpcUa is read-only against FOCAS by design — no cnc_wrparam / pmc_wrpmcrng / cnc_wrmacro path is implemented
ITagDiscovery	DiscoverAsync	Emits FOCAS/{device}/{tag} folders per configured device
ISubscribable	polled via shared PollGroupEngine	FOCAS has no push model — subscriptions turn into per-tag polling groups
IHostConnectivityProbe	periodic cnc_rdcncstat	Probe cadence is Probe.Interval; transitions fire OnHostStatusChanged
IPerCallHostResolver	lookup in _tagsByName	Each call routes to the device of the referenced tag
IAlarmSource	polled cnc_rdalmmsg2 via FocasAlarmProjection	Opt-in — set AlarmProjection.Enabled=true; diffs (AlarmNumber, Type) between ticks

Ack is a no-op — FANUC clears alarms on its own once the underlying condition resolves, so AcknowledgeAsync swallows the batch rather than surfacing BadNotSupported.

Fixed node tree

Enable a pre-defined hierarchy of CNC nodes populated automatically from cnc_sysinfo + cnc_rdaxisname + cnc_rddynamic2 + related FWLIB calls, so operators get an out-of-the-box view of identity / axes / program / timers without declaring per-address tags.

"Config": {
  "Devices": [ ... ],
  "Tags":    [ ... ],
  "FixedTree": {
    "Enabled": true,
    "PollInterval": "00:00:00.250",       // fast — per-axis dynamic reads
    "ProgramPollInterval": "00:00:01",    // medium — program + mode changes
    "TimerPollInterval": "00:00:30"       // slow — cumulative counters
  }
}

Enabled defaults to false so an upgrade does not grow nodes on configs that never asked for them. You do not have to set it to use the tree: authoring any FIXED: tag arms the poll loop by itself, because committing those tags already says you want it. The flag remains the way to publish the tree without authoring anything (and the browser turns it on for the duration of a browse).

Authoring fixed-tree tags

Browse the device (/raw → device → Browse device…, or the tag modal's Browse machine) and commit the leaves you want. Each leaf carries its own FIXED: address, so the commit produces working tags with no editing. The manual composer next to the browser covers PMC / PARAM: / MACRO: only — fixed-tree paths are discovered from the machine, not composed from parts.

Two caveats worth knowing before you browse:

• A real CNC can report duplicate sibling names, and they are disambiguated automatically (#548). One observed Makino returns two axes both called AA; every member of such a collision set gets a 1-based occurrence suffix in slot order — the tree offers Axes/AA_1/ and Axes/AA_2/, each reading its own axis — while unique names stay bare (Axes/Y/). The bare name of a duplicate set deliberately does not resolve: a tag authored against Axes/AA/… on such a machine reads BadNodeIdUnknown rather than one arbitrary axis's data. The suffix counts occurrences of the same name, so adding an unrelated axis never renames an existing pair — but if the collision-set membership itself changes (a third AA appears, or one of two is removed), the segments change on the next browse, and previously committed tags on the old segments read Bad until re-committed. The same rule covers spindles.
• Values are dated from the last answered poll, not from the read. If a CNC stops answering, its fixed-tree values go BadCommunicationError rather than continuing to serve the last snapshot as Good; the budget is eight poll cadences, floored at 30 s.

What gets populated (all under FOCAS/{deviceHostAddress}/, addressed as FIXED:{subtree}/{field}):

Subtree	Nodes	Source call
Identity/	SeriesNumber, Version, MaxAxes, CncType, MtType, AxisCount	cnc_sysinfo once at bootstrap
Axes/{name}/	AbsolutePosition, MachinePosition, RelativePosition, DistanceToGo, ServoLoad — one folder per discovered axis	cnc_rdaxisname once + cnc_rddynamic2 + cnc_rdsvmeter per tick
Axes/FeedRate/Actual, Axes/SpindleSpeed/Actual	Current feed + spindle RPM	cnc_rddynamic2
Spindle/{name}/	Load (percentage), MaxRpm — one folder per discovered spindle	cnc_rdspdlname once + cnc_rdspload + cnc_rdspmaxrpm
Program/	Name (filename), ONumber, Number, MainNumber, Sequence, BlockCount	cnc_exeprgname2 + cnc_rdblkcount + cached cnc_rddynamic2
OperationMode/	Mode (int), ModeText ("AUTO", "MDI", "EDIT", …)	cnc_rdopmode
Timers/	PowerOnSeconds, OperatingSeconds, CuttingSeconds, CycleSeconds	cnc_rdtimer × 4

Per-series node suppression

The driver probes each optional call once at bootstrap. If the target CNC returns EW_FUNC / EW_NOOPT / EW_VERSION on the wire, the corresponding subtree is not emitted — the operator doesn't see nodes that will only ever return BadDeviceFailure. Capability suppression covers Spindle/, Program/ + OperationMode/, Timers/, and per-axis ServoLoad independently. Identity + Axes/* position reads (which every Fanuc CNC supports) are always emitted.

Position values (AbsolutePosition, MachinePosition, RelativePosition, DistanceToGo) are CNC-internal scaled integers exposed as Float64 OPC UA nodes. The driver converts them to engineering units using the per-device PositionDecimalPlaces config field (default 0 = no scaling). When set to a positive integer d, each position value is divided by 10^d before publishing, so a CNC that reports millimetres × 1000 is corrected by setting PositionDecimalPlaces: 3.

"Devices": [
  {
    "HostAddress": "focas://10.20.30.40:8193",
    "Series": "ThirtyOne_i",
    "PositionDecimalPlaces": 3   // 123456 → 123.456 mm
  }
]

The driver now attempts to auto-scale each axis position using the CNC's cnc_getfigure figure when available; PositionDecimalPlaces is the per-axis fallback used only when the CNC reports no figure for that axis. Caveat: the managed WireFocasClient (FOCAS/2 Ethernet wire protocol) does not issue cnc_getfigure today, so on real hardware all axes still fall back to the manual PositionDecimalPlaces config field. Live auto-fetch is a follow-up requiring a cnc_getfigure command in FocasWireClient. Negative values from PositionDecimalPlaces are clamped to 0.

Follow-ups (known gaps, non-blocking):

• No upper-bound clamp on the figure magnitude returned by the CNC — a misbehaving figure could overflow Math.Pow; a max-figure guard should be added.
• The negative-figure branch (falls back to manual PositionDecimalPlaces) is handled but not explicitly unit-tested.

Still hand-authored: PARAM:6711, MACRO:500, R100 etc. — specific numbers whose meaning is MTB-specific, and which no browse can discover. Those go under the device folder alongside the fixed subtree.

Alarm projection

Alarm surfacing is disabled by default because the polling cost is wasted on sites that don't consume CNC alarms. Opt in per driver instance:

"Config": {
  "Devices": [ ... ],
  "Tags":    [ ... ],
  "AlarmProjection": {
    "Enabled": true,
    "PollInterval": "00:00:02"
  }
}

Every alarm transition fires OnAlarmEvent with:

• SourceNodeId = the device host address (FOCAS has no per-node alarm model; the CNC exposes a single flat active-alarm list per session)
• ConditionId = "{host}#{Type}:{AlarmNumber}"
• AlarmType = projected from FANUC's ALM_TYPE_* (e.g. Overtravel, Servo, Parameter, MacroAlarm)
• Severity = Overtravel / Servo / PulseCode → Critical; Parameter / Macro → Medium; everything else → High

Cleared alarms fire a second event with " (cleared)" appended to the message so downstream consumers can ignore the clear if they only care about raises.

Handle recycling

FANUC CNCs have a finite FWLIB handle pool (~5–10 concurrent connections) and certain series have documented handle-leak bugs that manifest after long uptime. The driver can proactively close + reopen each device's session on a cadence to release its slot back to the pool:

"Config": {
  "Devices": [ ... ],
  "HandleRecycle": {
    "Enabled": true,
    "Interval": "01:00:00"
  }
}

Disabled by default — a healthy CNC + driver doesn't need it. Enable when field experience shows handle exhaustion. Typical tuning: 30 min for sites running multiple OtOpcUa instances against the same CNC (they share the pool); 6 h for a single-client deployment. Reads / writes during recycle simply wait for the reconnect rather than failing — worst case, an operator sees a brief read latency spike once per cadence.

Testing

• Unit tests — tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/ cover the driver surface via FakeFocasClient. Includes the alarm-projection raise / clear diffing tests.
• Integration tests — tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.IntegrationTests/ hold the Docker simulator scaffold; see docs/v2/implementation/focas-wire-protocol.md for what the simulator emits vs. real CNC behaviour.
• E2E script — scripts/e2e/test-focas.ps1 stages Host + Proxy + a real CNC (or the simulator) and exercises connect → read → write → subscribe round-trips. See docs/drivers/FOCAS-Test-Fixture.md for the coverage map.

Troubleshooting

Symptom	Likely cause	Fix
Driver faults immediately at startup with "unimplemented" in the error	Backend is "unimplemented" / "none" / "stub"	Change Backend to "wire" and supply the real CNC endpoint in Devices[]
BadCommunicationError on every read	CNC unreachable on TCP:8193	Check firewall / LAN reachability; FOCAS Ethernet option must be licensed on the CNC side
Every read returns BadNotWritable on writes	Expected — OtOpcUa is read-only against FOCAS	If you actually need writes, open a feature request — the driver's managed wire client doesn't expose the write commands
BadOutOfRange on reads for a macro/parameter	Config address outside the declared Series range	Check docs/v2/focas-version-matrix.md — either fix the address or widen the Series
Alarm events never fire	AlarmProjection.Enabled left at default (false)	Set it to true in the driver config
Axis position values seem 1000× too large	PositionDecimalPlaces not set	Add "PositionDecimalPlaces": 3 (or the MTB-specific value) to the device entry in Devices[]

Further reading

• docs/v2/driver-specs.md §7 — full OPC UA node mapping, pre-defined tag set, per-API notes
• docs/v2/focas-version-matrix.md — per-series macro / parameter / PMC range table
• docs/v2/implementation/focas-wire-protocol.md — captured FOCAS2 wire semantics (magic prefix, handshake, command-id table)
• upstream Focas.Wire — the managed client implementation OtOpcUa consumes as a NuGet dependency