FANUC FOCAS Ethernet Integration Guide

Read FANUC CNC controllers directly over FOCAS Ethernet: no adapter, no FOCAS library, no Windows host.

Protocol

FOCAS2/Ethernet, binary over TCP

Default port

8193

Operations

Read · Status

Writes

None: read-only by construction

Read FANUC CNC controllers straight from MaestroHub over the controller's own Ethernet port. The connector speaks the FOCAS2/Ethernet protocol on TCP 8193 itself, so it needs no FOCAS adapter, no FANUC fwlib32 library and no Windows machine in between. One MaestroHub connection targets one CNC and holds one FOCAS session on it.

Overview

The FANUC FOCAS Ethernet connector provides:

• Direct connection: MaestroHub talks to the CNC; nothing to install next to it
• Machine status: run state, mode, motion, emergency stop and alarm, in one call or as single addresses
• Program and motion: running and main program numbers, actual feed rate, active spindle speed, absolute, relative and distance-to-go axis positions
• Macro variables and PMC memory: custom macro variables (an empty variable reads as null, never 0) and PMC areas as bits, bytes, words and double words
• Batch reads with per-address errors: one bad address never fails the others
• The same addresses and results as the FANUC FOCAS (adapter) connector, so a pipeline moves between the two unchanged

Read-only

The connector cannot change anything on the controller. It contains only read calls: there is no write, no program download and no parameter change, by construction.

Which FANUC connector should I use?

	FANUC FOCAS Ethernet (this connector)	FANUC FOCAS (adapter)
What it needs	Network access to the CNC on TCP 8193	The MaestroHub FOCAS Adapter on a Windows host, with your FANUC fwlib32 library
Reads	Yes	Yes
Writes (macros, PMC)	No	Yes
Change-pushed subscriptions	No: poll with a Schedule trigger	Yes
Machine position, alarm messages	Not yet	Through the adapter

Choose this connector when reading is all you need and you would rather not run an adapter.

Supported controllers

FANUC CNCs with an Ethernet port and the FOCAS Ethernet function, such as the 0i, 16i/18i/21i and 30i/31i/32i series. The connector reads the controller's identity when it connects and reports it in the Status result.

FANUC has not published the FOCAS2/Ethernet protocol. The connector is built from public, independent descriptions of it, and every value is decoded strictly: a reply with a length or layout the connector does not recognise is reported as an UNSUPPORTED_ON_MODEL error for that address, never guessed. If a controller returns such errors for addresses it should support, contact MaestroHub support: they will send a small read-only capture tool whose output lets us add that controller.

Security

FOCAS Ethernet has no encryption and no authentication: anyone who can reach port 8193 can read the controller, and other software can write to it. Keep CNCs on an isolated machine network, and let only the MaestroHub host reach port 8193 through your firewall.

Connection Configuration

Creating a FANUC FOCAS Ethernet Connection

Navigate to Connections → New Connection → FANUC FOCAS Ethernet and fill in the form. It has four tabs: Connection, Functions, Scaling and Health. Functions, Scaling and Health unlock after the connection is saved.

1. Profile Information

Field	Default	Description
Profile Name	-	A descriptive name for this connection profile (required, max 100 characters). Must be unique across all connections.
Description	-	Optional description for this connection
Labels	-	Key-value pairs to categorize and organize the connection (max 10 labels)

2. CNC Settings

Field	Default	Description
CNC Address	-	Host name or IP address of the CNC's Ethernet port (required)
Port	8193	The FOCAS Ethernet TCP port, set on the CNC's Ethernet setting screen
Connection Timeout	5s	Maximum time to open the TCP connection, open the FOCAS session and read the controller identity

Testing the Connection

Test Connection dials the CNC, opens a FOCAS session, reads the controller identity and closes the session again. It passes only when the CNC answered all three.

Function Builder

Creating FANUC FOCAS Ethernet Functions

Open the connection's Functions tab and choose New Function. There are two function types:

Function	Operation	What it does
Read	fanuc_ethernet.read	Reads a list of addresses, each with its value or its own error
Status	fanuc_ethernet.status	Reads the controller identity and a machine snapshot in one call

Read (fanuc_ethernet.read)

Field	Required	Description
Addresses	Yes	One to 500 addresses (see Address Catalog). The Browse panel lists every address the connected controller offers; pick one to add it.
Timeout	No	Bound on this single read (30s, 5m)

Each address comes back as one item in values, in the order requested:

{
  "values": [
    { "address": "status.run", "value": "EXECUTING", "ts": "2026-11-03T10:00:00.120Z" },
    { "address": "macro.501", "value": null, "ts": "2026-11-03T10:00:00.125Z" },
    { "address": "axis.9.pos.abs", "error": { "code": "INVALID_ADDRESS", "message": "\"axis.9.pos.abs\": the controller has 3 axes" } }
  ]
}

A read where some addresses fail still succeeds, marked partial, with the failures named in its summary. Addresses answered by the same controller call (for example status.run and status.mode) share one round trip.

Status (fanuc_ethernet.status)

No fields besides the timeout. Returns:

{
  "cncHost": "192.168.1.50",
  "cnc": { "series": "G431", "version": "0010", "cncType": "31", "mtType": "M", "axisCount": 3, "maxAxis": 32 },
  "snapshot": {
    "run": "EXECUTING", "mode": "MEM", "motion": true, "estop": false, "alarm": false,
    "runningProgram": 1234, "mainProgram": 100, "feedRate": 1500.0, "spindleSpeed": 3000.0
  }
}

Run state and mode are required: without them there is no snapshot and the call fails. A snapshot field the controller refuses is left out and listed under unavailable with its error, so a missing value never reads as 0.

Testing Functions

Use Test Function on a function to run it once against the CNC and see the whole result.

Address Catalog

Addresses are dotted and case-insensitive, and contain no spaces. They are the FANUC FOCAS (adapter) connector's addresses, limited to what the direct connector reads.

Address	Value	Notes
cnc.series, cnc.version, cnc.cncType, cnc.mtType	text	Controller identity, as the CNC reports it
cnc.axisCount, cnc.maxAxis	number	Controlled axes; most axes the controller supports
status.run	text	STOPPED, HOLD, EXECUTING, MSTR or UNAVAILABLE
status.mode	text	MDI, MEM, EDIT, HANDLE, JOG, TEACH, REMOTE or UNAVAILABLE
status.motion, status.estop, status.alarm	true/false	An axis moving; emergency stop; any alarm present
status.runCode, status.modeCode	number	The raw numbers behind status.run and status.mode
program.running, program.main	number	Running and main program numbers
feed.actual	number	Actual feed rate
spindle.1.speed	number	Actual speed of the active spindle
axis.<n>.pos.abs, .rel, .dtg	number	Absolute, relative position and distance to go of axis n (1 to the axis count)
macro.<n>	number or null	Custom macro variable #n; null when the variable is empty
pmc.<area>.<address>[.<type>]	number or true/false	PMC memory; see below
alarm.bits	number	Alarm-type bitfield; 0 when no alarm is present

Numbers carry their own scale on the wire (the controller reports the decimal places with each value), so positions, feed and macros need no decimal-places setting.

PMC addresses

pmc.<area>.<address>[.<type>], for example pmc.G.0.bit3, pmc.R.100 or pmc.D.200.word:

• <area>: G, F, Y, X, A, R, T, K, C, D, M, N, E or Z
• <address>: the byte address within the area, 0 to 65535
• <type>: bit0 to bit7 (true/false), byte (0 to 255, the default), word (signed 16-bit) or dword (signed 32-bit)

PMC float and the machine position (pos.mach) are not readable over the direct connection yet; reading them returns INVALID_ADDRESS with that explanation.

Error Codes

Code	Meaning
INVALID_ADDRESS	The address is not in the catalog, or the controller refused its number (an axis it does not have, a macro number out of range, a PMC address outside the area). Nothing is sent for an address the connector can refuse itself.
UNSUPPORTED_ON_MODEL	The controller does not offer this data (the function or option is missing), or answered in a layout the connector does not recognise
BUSY	The controller was busy; the next read usually succeeds
INTERNAL	Any other refusal; the message carries the controller's return code

A broken or silent connection fails the whole read and the connection reconnects; values are never returned from a read that did not complete.

Pipeline Integration

Each function type has its node in the Pipeline Designer, under FANUC FOCAS Ethernet: FANUC FOCAS Ethernet Read and FANUC FOCAS Ethernet Status. See the FANUC FOCAS Ethernet nodes for their outputs. To read on a timer, start the pipeline with a Schedule trigger.

Common Use Cases

Machine status to a dashboard or the UNS

Poll Status every few seconds with a Schedule trigger and publish the snapshot to the UNS, so every dashboard reads one current machine state.

Production counting from macro variables

Many part programs count parts in a macro variable. Read macro.<n> on a schedule and write it to a historian; an empty variable arrives as null, so a reset program never looks like a count of zero.

OEE inputs

status.run, status.alarm and program.running together give availability and the running job; feed.actual and spindle.1.speed show whether the machine is cutting.

Troubleshooting

Connection Issues

Symptom	Cause and fix
Test Connection times out	The CNC is unreachable: check the address, the port (CNC Ethernet setting screen) and any firewall between MaestroHub and the CNC
"the CNC did not open a FOCAS session"	Either the FOCAS Ethernet function is not enabled on the CNC, or every FOCAS session is in use (MES, DNC or monitoring software hold them). The two look the same on the wire: check the CNC's Ethernet settings, and close sessions held by other software.
Works, then fails after a few minutes	Another program may be taking the last FOCAS session when MaestroHub reconnects; one MaestroHub connection holds exactly one session

Read Issues

Symptom	Cause and fix
INVALID_ADDRESS on an axis	The address names an axis above the controller's axis count (see cnc.axisCount)
UNSUPPORTED_ON_MODEL on an address the controller should support	The controller answered in a layout the connector does not recognise yet. Contact MaestroHub support for the capture tool.
A macro reads null	The variable is empty on the controller (it shows blank on the macro screen)

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FANUC and FOCAS are trademarks of FANUC Corporation. MaestroHub is not affiliated with or endorsed by FANUC; this connector is compatible with FANUC CNCs that provide FOCAS Ethernet.