Why should I buy and use FOCAS?

If you run FANUC-controlled machines and someone has mentioned "FOCAS" while talking about connecting them to a monitoring system, this is what that word actually means. FOCAS is the standard way to pull data out of a FANUC controller programmatically, and it shows up in almost every serious FANUC connectivity project — whether you're evaluating a monitoring platform, building an in-house connector, or just trying to understand what a vendor's spec sheet is referring to.

Contents:

1. What FOCAS is
2. How FOCAS works
3. FOCAS1 vs. FOCAS2
4. What data you can collect through FOCAS
5. Licensing and cost
6. Building your own connector vs. buying one
7. Common implementation challenges
8. Frequently asked questions
9. Conclusion

What FOCAS is

FOCAS (FANUC Open CNC API Specification) is FANUC's own software library for reading data from, and in some cases writing data to, FANUC CNC controllers. It is not an open, vendor-neutral standard like MTConnect or OPC UA — it is a proprietary interface that FANUC provides so that software developers can build applications that talk directly to a FANUC controller over Ethernet.

We go into the technical details of the library itself in a dedicated technical guide; this article focuses on what FOCAS means practically for a manufacturer deciding how to connect FANUC equipment to a monitoring or MES system.

How FOCAS works

• It's a function library, not a message format. FOCAS is distributed as a set of functions (a DLL on Windows, or equivalent libraries on other platforms) that a developer calls from their own application code — there is no standardized document format being exchanged, unlike MTConnect's XML or OPC UA's structured address space.
• Connection is over Ethernet. A client application using the FOCAS library connects directly to the controller's IP address and calls functions to request specific pieces of data — program status, alarm state, axis load, and so on.
• Each function call maps to a specific data request. Unlike a browsable address space, FOCAS requires the developer to know in advance which function retrieves which piece of information, based on FANUC's documentation.
• The controller must have Ethernet and the appropriate option enabled. Older or minimally configured FANUC controllers may need an additional hardware or software option activated before FOCAS access is possible at all.

FOCAS1 vs. FOCAS2

FANUC has released two generations of the library. FOCAS2 is the current, actively supported version and the one almost all new integrations should target; FOCAS1 is the older generation, still encountered on legacy setups but generally being phased out. The two are not interchangeable at the code level, and a connector built against one typically needs rework to run against the other. We cover the practical differences — supported controllers, function sets, and migration considerations — in a separate comparison.

What data you can collect through FOCAS

Exact availability depends on the controller series (0i, 30i, 31i, and so on) and firmware — not every data point above is exposed on every FANUC controller, so it's worth confirming against the specific model before assuming a given metric is reachable.

Licensing and cost

FOCAS itself is a FANUC-provided library, and using it typically requires a license agreement with FANUC — this is different from royalty-free open standards like MTConnect. The details of how that licensing works, who needs to sign it (an integrator, an OEM, or the end manufacturer), and what it costs are covered in our OEM protocol licensing guide. It's a step that's easy to underestimate early in a connectivity project, since it can affect both timeline and total cost depending on how the license is structured.

Building your own connector vs. buying one

Writing a FOCAS-based connector in-house is possible — FANUC publishes the library and reference documentation — but it's a real software project, not a configuration task: it means handling connection stability, reconnect logic, mapping raw function output to usable metrics, and maintaining that code as controller firmware or your monitoring needs change. Ready-made monitoring platforms that already include a maintained FOCAS connector remove that ongoing engineering burden at the cost of a license or subscription fee. We break down the real cost comparison, including engineering time most teams underestimate, in build vs. buy: FANUC connector cost.

Common implementation challenges

• Controller-specific function availability. Not every FOCAS function works identically across every FANUC controller series, which means testing against your actual fleet, not just the documentation, is necessary.
• Ethernet option not enabled. Some older or budget-configured controllers need an Ethernet board or software option activated by FANUC or a service technician before FOCAS can connect at all.
• Licensing overhead at scale. A connector that works fine on one machine can hit licensing friction when rolled out across a large, mixed-generation fleet if the license terms weren't scoped for that from the start.
• No built-in standardized vocabulary. Unlike MTConnect, FOCAS doesn't enforce naming or units across implementations — two different connectors built against FOCAS can structure the same data differently, which matters when comparing metrics across machines or integrating with other systems.

Frequently asked questions

Is FOCAS the same as MTConnect for FANUC machines?

No. FOCAS is FANUC's proprietary library specific to FANUC controllers, while MTConnect is an open, vendor-neutral standard that a machine builder can implement regardless of controller brand. Some FANUC-controlled machines support both, often through an MTConnect adapter that uses FOCAS internally to read the controller.

Do I need to be a software developer to use FOCAS?

To build a connector from scratch, yes — FOCAS is a programming library, not an end-user tool. Manufacturers who don't want to build custom software typically use a monitoring platform that already includes a maintained FOCAS-based connector.

Does every FANUC controller support FOCAS?

Most modern FANUC controllers support it, but availability and the specific function set depend on the controller series, firmware version, and whether the necessary Ethernet option is enabled. Very old controllers may not support it at all.

Can FOCAS be used to send commands to the machine, not just read data?

FOCAS does include some write-capable functions, but most monitoring use cases only use the read functions. Any write-capable connection should be deliberately scoped and secured, since it can affect machine behavior rather than just report on it.

Conclusion

FOCAS is the practical answer to "how do I get data off my FANUC machine," and it underlies most FANUC connectivity, including many MTConnect adapters that use it internally. The decisions that actually matter for a manufacturer are less about whether to use FOCAS and more about which version to target, how licensing is structured, and whether to build a connector in-house or use a platform that already maintains one.

Related articles:

• FOCAS: A Technical Guide for FANUC Connectivity
• Understanding FOCAS1 vs. FOCAS2
• OEM CNC Protocol Licensing Guide
• Build vs. Buy: FANUC Connector Cost
• MDCplus vs. FANUC FIELD System

About MDCplus

Our key features are real-time machine monitoring for swift issue resolution, power consumption tracking to promote sustainability, computerized maintenance management to reduce downtime, and vibration diagnostics for predictive maintenance. MDCplus's solutions are tailored for diverse industries, including aerospace, automotive, precision machining, and heavy industry. By delivering actionable insights and fostering seamless integration, we empower manufacturers to boost Overall Equipment Effectiveness (OEE), reduce operational costs, and achieve sustainable growth along with future planning.