The Fanuc FOCAS (Fanuc Open CNC API Specifications) library is the standard protocol for extracting real-time data from Fanuc CNC controllers. While Fanuc does not provide official Python hooks, developers use community-driven wrappers or custom libraries to interface with the native C libraries. FOCAS Overview and Setup
To use FOCAS with Python, the CNC machine must be configured for Ethernet communication. Versions:
FOCAS 1: Older library for legacy CNCs, typically used with Windows 7.
FOCAS 2: Modern library compatible with newer controllers and Windows 10/11. Machine Configuration: Access the SYSTEM hardkey and navigate to EMBDD settings. Set a static IP address, Subnet, and Gateway. Set the FOCAS port to TCP 8193. Restart the CNC to apply changes. Python Integration Options
Since there is no native Python library from Fanuc, you must use one of the following methods: pyfanuc · PyPI
FANUC FOCAS (Fanuc Open CNC API Specifications) is a specialized communication protocol and a set of library files ( DLLcap D cap L cap L
s) used to exchange data between a PC and a FANUC CNC controller. While FANUC does not provide official Python hooks, developers use Python by wrapping these DLLcap D cap L cap L files to enable real-time monitoring and automation. Core Capabilities
The FOCAS library acts as an intermediary, allowing your Python scripts to "ask" the machine questions and receive detailed data:
Machine Status: Monitor running state, idle time, or active alarms. fanuc focas python
Positional Data: Read absolute and relative positions for all axes.
Program Management: Upload, download, search, or delete CNC programs.
Production Metrics: Track part counts, cycle times, and feedrate overrides.
Tooling & Offsets: Access tool information and workpiece offsets. Python Integration Methods Since FOCAS is natively written for
, Python integration typically requires one of the following: Overview | General | Fanuc Focas Library - inventcom
The Challenge
John, a skilled CNC programmer, was tasked with automating a complex machining process on a FANUC-controlled CNC machine. The goal was to write a program that could read data from a file, send it to the CNC machine, and then retrieve the machining results. The catch was that the CNC machine was located in a different part of the factory, and John needed to control it remotely.
The Solution
John had heard about FANUC's FOCAS (FANUC Open CNC API) library, which allowed developers to create custom applications to control FANUC CNC machines. He decided to use Python, a language he was familiar with, to create a program that could communicate with the CNC machine using FOCAS.
John downloaded the FANUC FOCAS Python library and started studying the documentation. He was impressed by the simplicity and flexibility of the API. With FOCAS, he could read and write data to the CNC machine, execute programs, and even retrieve machining results.
The Code
John wrote a Python script that used the FOCAS library to connect to the CNC machine. He imported the necessary modules and created a Focas object to represent the CNC machine.
import focas
# Create a Focas object
cnc = focas.Focas("192.168.1.100", 8193) # IP address and port of the CNC machine
# Read data from a file
with open("data.txt", "r") as f:
data = f.read()
# Send the data to the CNC machine
cnc.write(100, data) # 100 is the address where the data will be written
# Execute a program on the CNC machine
cnc.exec_program(" machining_program")
# Retrieve machining results
results = cnc.read(200, 100) # 200 is the address where the results are stored, 100 is the length of the data
# Print the results
print(results)
The Result
John ran the script, and to his delight, it worked seamlessly. The CNC machine received the data, executed the program, and sent back the machining results. John was able to monitor the process remotely and verify that the results were accurate.
The automation of the machining process not only saved John time but also improved the overall efficiency of the factory. The use of FANUC FOCAS Python library allowed John to create a custom solution that met the specific needs of the factory.
The Future
John's success with FANUC FOCAS Python sparked his interest in exploring more automation projects. He began to investigate other FANUC products and tools, such as the FANUC ROBOT and FANUC's IIoT platform. He realized that the possibilities for automation and innovation were endless, and he was excited to see what the future held.
From that day on, John became a advocate for using FANUC FOCAS Python in automation projects, sharing his knowledge and expertise with others in the industry. The story of John and his FANUC FOCAS Python project served as an inspiration to others, demonstrating the power of automation and the importance of innovation in manufacturing.
Fanuc FOCAS (Fanuc Open CNC API Specifications) is a set of dynamic link libraries (DLLs) that allow applications to access data from Fanuc CNC controllers. While Fanuc does not provide official Python hooks—relying instead on C, C++, and .NET—Python developers can integrate with FOCAS using third-party wrappers or low-level library calls. Implementation Methods
To bridge the gap between Python and the FOCAS DLLs, you can use several established approaches:
Third-Party SDKs: Libraries like the UnderAutomation Fanuc SDK provide a structured Python interface, often utilizing pythonnet to communicate with the underlying .NET/C components.
Low-Level Wrappers: The ctypes or cffi libraries in Python allow you to call functions directly from the FOCAS Fwlib32.dll or Fwlib64.dll.
Open-Source Projects: Community efforts such as pyfanuc attempt to reverse-engineer the wire protocol, which can be useful for non-Windows platforms (like Linux/Raspberry Pi) where official DLLs may not run natively.
Python-Fanuc read Parameter Variable pyfanuc - Stack Overflow The Fanuc FOCAS (Fanuc Open CNC API Specifications)
handle = ctypes.c_ushort(0)
0 for success (EW_OK). Any other number is an error code (e.g., EW_SOCKET for network issues, EW_HANDLE for invalid handle).| Use Case | FOCAS Function Area | Python Outcome |
|----------|---------------------|----------------|
| OEE Dashboards | cnc_rddynamic, cnc_rdoption, rdopn | Real-time % utilization, idle time detection |
| Predictive Maintenance | cnc_rdaxisdata (servo load, torque) | Trend analysis to predict bearing/tool wear |
| Program Management | cnc_upload, cnc_download | Automatic backup of all CNC part programs |
| Alarm Monitoring | cnc_rdalarmmsg | Push alerts to Slack, Telegram, or email |
| Energy Monitoring | cnc_rdpower (on supported models) | Track energy per part produced |