Fanuc FOCAS (CNC) Driver

Overview

FOCAS = Fanuc Open CNC API Specification. It is the de facto standard API for reading spindle load / axis position / part programs / alarms / OEE metrics from Fanuc CNC (Computer Numerical Control) controllers. Machine tool OEMs such as Mazak, DMG MORI, and Doosan expose the same interface whenever they adopt Fanuc as the controller.

Item	Value
`opc_type`	`FOCAS`
Implementation class	`plantpulse.driver.protocol.focas.FOCASDriver`
Library	(none — stub)
Target controllers	Fanuc 0i / 30i / 31i / 32i / 35i, Power Mate, FS18i, etc.
Communication medium	Ethernet (TCP, default port 8193) — HSSB optical cards are separate
read	stub (returns `""`)
write	stub

Current status: stub driver

Only a stub of FOCAS exists. To communicate with an actual Fanuc controller, use one of the bridge patterns described in Alternative operating methods below. There is no plan to embed the native FwLib inside the single PlantPulse code base jar.

Why a native implementation is difficult

The FOCAS wire protocol is proprietary. Fanuc does not publish the wire specification and instead distributes a C library called FwLib (Focas Library) to licensed subscribers. In other words, speaking FOCAS directly from the Java side requires one of the following.

Dependency	Description	Deployment impact
`Fwlib32.dll` (Windows)	32-bit DLL — Fanuc license required	Requires an x86 JVM or IPC separation
`libfwlib32.so` (Linux)	x86-64 / ARM builds — separate per license	OS / glibc version matching
HSSB card driver	PCI card for optical communication — 1:1 with the controller	Linux kernel module required
License key	Registration as a member company entitled to use FwLib	Redistribution not permitted
JNI binding	Java `<->` C memory model / threading	A failed call can crash the JVM

As with ROS 2 / DALI / IO-Link, embedding a native library is cost > benefit under the PlantPulse Edge policy of single-jar deployment + support for a wide range of OS / ARCH combinations. Furthermore, license policy means FwLib is not a component PlantPulse can freely redistribute.

Alternative operating methods

Fortunately, Fanuc and third parties already provide standard bridges. PlantPulse only needs to consume the bridge's output interface (HTTP / OPC UA).

Option 1. MTConnect Adapter / Agent (recommended)

Most modern machine tools / Fanuc CNCs adopt MTConnect (ANSI/MTC1.4) as their primary integration path. Fanuc provides its own FOCAS-MTConnect Adapter free of charge, and OEMs (Okuma, DMG MORI, Mazak SmartBox) follow the same standard.

PlantPulse driver to use	Page
`HTTP` (REST polling; XML parsing handled in the formula / ingest pipeline)	HTTP

Option 2. OPC UA (Fanuc CNC OPC UA option or KEPServer)

Newer Fanuc controllers expose an OPC UA Server as an add-on option. Older controllers are converted using a commercial gateway such as Kepware KEPServerEX Fanuc Suite or Matrikon FOCAS OPC Server.

PlantPulse driver to use	Page
`OPCUA`	OPC-UA

Option 3. Direct FwLib JNI (sidecar)

Sites that hold an FwLib license can run their own JNI module as a separate jar (motorsensor.jar pattern) or as a sidecar process (e.g. focas-grpc-server), with PlantPulse polling its output. Even in this case the main PlantPulse jar is unchanged, and the FOCAS driver can remain a stub.

Which option to choose

Situation	Recommendation
OEM (Mazak SmartBox / DMG MORI Celos / Okuma) already runs an MTConnect Agent	MTConnect → HTTP
Newer Fanuc 30i, OPC UA option can be added	Fanuc OPC UA → OPCUA
Older Fanuc 0i, SI holds a license	KEPServerEX Fanuc Suite → OPCUA
Own FwLib license / custom data required	focas-grpc sidecar → HTTP
Only a simple availability (0/1) metric needed	Controller digital output → Modbus/Ethernet IO module

Considerations for a future native implementation

Option	Dependencies	Difficulty
Embed FwLib JNI directly	Requires x86 / x64 / ARM builds, plus a license	Very high
Separate `plantpulse-edge-driver-focas.jar` (motorsensor.jar pattern)	Library loaded by reflection	High
Sidecar + gRPC	FwLib lives only in the sidecar; PlantPulse is an HTTP/gRPC client	Medium
Reverse-engineered wire protocol (3rd-party)	Risk of violating the Fanuc license	Not recommended

Conclusion

The official integration path recommended by PlantPulse Edge is MTConnect (HTTP driver). OEMs already supply an MTConnect Adapter, and it sidesteps all license / deployment / OS compatibility issues. If the Fanuc OPC UA option is available, connecting directly with the OPCUA driver is the cleanest route.

stub registration (test only)

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_FOCAS_STUB",
    "opc_type": "FOCAS",
    "opc_name": "FANUC FOCAS stub",
    "opc_agent_ip": "192.168.0.0",
    "opc_agent_port": "8193",
    "site_id": "SITE_00001",
    "auto_collect": false,
    "timecycle": 5000,
    "tag_list": []
  }'

Overview​

Why a native implementation is difficult​

Alternative operating methods​

Option 1. MTConnect Adapter / Agent (recommended)​

Option 2. OPC UA (Fanuc CNC OPC UA option or KEPServer)​

Option 3. Direct FwLib JNI (sidecar)​

Which option to choose​

Considerations for a future native implementation​

stub registration (test only)​