The Fanuc 0-T (often written as Fanuc OT) is a legendary workhorse in the world of CNC turning. While standard parameters handle day-to-day operations like feed rates and motor tuning, the 900-series parameters are the "keys to the kingdom"—they unlock machine options that were originally sold as premium add-ons by the manufacturer. The "Secret" Nature of 900 Parameters
In the Fanuc universe, 900-series parameters are unique because they are bit-based. Instead of a single number, each parameter is a string of eight 0s and 1s. Flipping a single bit from 0 to 1 can suddenly give your machine a feature it didn't have yesterday, such as:
Canned Cycles: Automating complex drilling or threading with a single line of code.
Custom Macros: Enabling "Custom Macro A" for advanced programming logic.
Memory Upgrades: Artificially expanding the storage for your NC programs. Essential Fanuc 0-T 900 Parameter Map
Based on technical documentation, here is a snapshot of what these bits actually control: Description Functionality Unlocked 900 CANNED CYCLE Enables standard G-code cycles like G81/G83. 900 G10 PROGRAM INPUT Allows software to update offsets automatically. 900 INCH / METRIC Toggle between imperial and metric measurement systems. 901 TAPE MEMORY Controls memory capacity (from 20M to 320M). 901 CHAMFER/RADIUS Enables corner rounding/chamfering G-codes. 902 CONSTANT SURFACE Allows the spindle to adjust speed based on diameter. 902 CUSTOM MACRO A Unlocks the ability to use variables and logic. 903 Enables the dynamic buttons below the CRT screen. 904 Changes the system text (Japanese, German, Spanish, etc.). How to "Unlock" These Settings
Because these parameters affect the machine’s core configuration, they are protected by a safety lock called PWE (Parameter Write Enable). fanuc ot 900 parameter list
Enter MDI Mode: You cannot change parameters while the machine is running or in Jog mode.
Toggle PWE: Go to the SETTING page and find PARAMETER WRITE. Change the 0 to a 1. The machine will trigger a "P/S 100" alarm—this is normal and just means the system is in "unlocked" mode.
Navigate to 900s: Press the SYSTEM key and search for the specific parameter (e.g., 901).
The Edit: Type the entire 8-bit string (e.g., 00100000) and press INPUT.
Restart: Many 900-series changes require a "Cold Start" (powering the machine off and back on) to take effect. A Word of Caution
The 900 parameters are essentially the "firmware" settings of your lathe. While it's tempting to "turn everything on," incorrect settings can cause system crashes or render the machine unresponsive. Always back up your existing parameters before making changes, as many older 0-T controls do not have a "factory reset" button that restores these specific bits. Fanuc Ot 900 Parameter List - Google Groups The Fanuc 0-T (often written as Fanuc OT
For over four decades, the FANUC Series 0-T (Model C, D, and later)—commonly known as the FANUC OT control—has been the backbone of CNC lathes worldwide. From Okuma to Mori Seiki, Hardinge to Haas’s early lathes, this control is legendary for its reliability. However, even the most robust systems encounter issues: mysterious alarms, sudden halts, or a machine that simply refuses to power up.
When standard troubleshooting fails, the 900 parameter list becomes your most powerful diagnostic tool.
Unlike standard 000–899 parameters that control feedrates, axis assignment, and user preferences, the 900–999 range (often referred to as Fanuc OT 900 parameters) governs the hardware configuration, software options, and built-in PMC (Programmable Machine Controller) diagnostics. Modifying these incorrectly can crash your machine—but understanding them can resurrect a dead control.
In this article, we will provide the definitive FANUC OT 900 parameter list, explain what each parameter does, how to view it, and how to safely use it for backup, recovery, and troubleshooting.
PWE back to 0.The FANUC OT 900 parameter list is the master key to the control’s firmware identity. While intimidating, it is completely readable and manageable if approached with respect and a solid backup.
For daily operators, your job is to back up and never modify these values unless under service guidance. For maintenance engineers, understanding bits like 904.7 (PMC enable) and 908.7 (turret type) will save hours of downtime. Introduction For over four decades, the FANUC Series
Keep a printed copy in the machine cabinet. Invest in a battery replacement schedule (every 12–24 months). And if you ever see a blank screen after a long weekend, you’ll know exactly where to start: parameter 900, bit by bit.
This helps the control identify the generation of the servo system.
In Fanuc 0-T controls, the 900-series parameters are System Configuration Parameters. They define the fundamental architecture of the machine.
Unlike standard parameters (which adjust feedrates or offsets), 900 parameters tell the CNC control:
Because these settings are tied to the specific hardware inside the electrical cabinet, they are unique to each machine. You cannot simply copy them from an identical machine unless the internal hardware boards (Servo Amplifiers, Spindle Amplifiers, and Axis Control PCBs) are also identical.
Have corrections or additions to the Fanuc OT 900 parameter list? Share your machine builder’s specific 900 map to help the community preserve these legendary controls.