Fanuc — Focas Python

Fanuc FOCAS (Fanuc Open CNC API Specifications) library is the standard interface for extracting high-level operational data from Fanuc CNC controllers

. While originally designed for C/C++ and C#, Python developers can leverage it through several open-source wrappers to automate data collection and machine monitoring. Core Libraries for Python Because the official FOCAS library relies on Windows DLLs ( fwlib32.dll

), Python implementations typically act as a bridge or wrapper for these files. Inductive Automation Forum

: A popular open-source library that allows you to read macro variables and axis data (speed, load, position). ChatterTools fanuc focas python

: Provides a simplified Python wrapper compatible with both Windows and Linux, designed specifically for building CNC-interfacing applications. Fanuc.py SDK

: A more comprehensive SDK for Python 3.7+ that can handle both robots and CNCs, supporting data reading/writing and program execution. Key Capabilities

Using these libraries, you can programmatically "ask" the CNC for nearly any internal status: www.robustel.store pyfanuc · PyPI Fanuc FOCAS (Fanuc Open CNC API Specifications) library

Bridging the Gap: A Guide to FANUC FOCAS with Python

In the world of CNC machining, FANUC controls are the industry standard. For decades, integrating these machines with external systems required specialized knowledge of C++ or VB.NET. However, with the rise of Industry 4.0 and data-driven manufacturing, Python has emerged as the dominant language for data analysis and automation.

This write-up explores how to connect Python to FANUC CNCs using the FOCAS (FANUC Open CNC API Specifications) library, bridging the gap between legacy industrial hardware and modern software development.

What is FANUC FOCAS?

FOCAS is a library of functions that allows external devices (PCs, edge gateways) to communicate directly with a FANUC CNC over Ethernet. It can read/write CNC data, manage programs, monitor machine status, and even send control commands. What is FANUC FOCAS

From a technical standpoint, FOCAS uses a proprietary protocol over TCP/IP. FANUC provides C/C++ libraries (fwlib32.dll on Windows, libfwlib64.so on Linux). To use Python, we need a wrapper around these native libraries.

The "Old Way" vs. The Python Way

Traditionally, FOCAS was accessed via C++, C#, or VB.NET. While powerful, these languages lack the agility and statistical libraries of Python.

C++: Fast, but verbose. Writing a simple data logger takes hundreds of lines.
Python: Slower than C++ (but fast enough for CNC polling), but with pandas, numpy, and prometheus_client, you can build a dashboard in 50 lines.

Step 3: Connect to the CNC

The core connection function is cnc_allclibhndl3. We must define the argument types so ctypes knows how to convert Python types to C types.

IP_ADDRESS = "192.168.1.100" # Replace with your CNC IP
PORT = 8193                  # Default Fanuc Port
TIMEOUT = 10
# Setup argument types for the connection function
focas.cnc_allclibhndl3.argtypes = [
    ctypes.c_char_p,  # IP address
    ctypes.c_ushort,  # Port
    ctypes.c_long,    # Timeout
    ctypes.POINTER(ctypes.c_ushort) # Handle pointer
]
focas.cnc_allclibhndl3.restype = ctypes.c_short # Returns EW_OK(0) on success
# Create a handle variable
libh = ctypes.c_ushort()
# Connect
print(f"Connecting to IP_ADDRESS...")
ret = focas.cnc_allclibhndl3(IP_ADDRESS.encode('utf-8'), PORT, TIMEOUT, ctypes.byref(libh))
if ret == 0:
    print("Connection Successful!")
else:
    print(f"Connection Failed. Error Code: ret")
    exit()

Unlocking Factory Data: A Guide to FANUC FOCAS with Python

In the modern manufacturing landscape, data is the new oil. For shops running FANUC CNC controls, the gateway to that data is FOCAS (FANUC Open CNC API Specification). Traditionally accessed via C++ or .NET, the combination of FOCAS with Python has become the "gold standard" for rapid development in IIoT (Industrial Internet of Things), predictive maintenance, and OEE tracking.

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