Fanuc Ot 900 Parameter List
When people search for the 900 list, they are usually looking for these specific functions. The exact parameter number can shift slightly based on the software version (Model A vs. Model B), but here is the standard mapping:
Parameter #902 (Software Option Bits)
Parameter #904 / #905 (Buffer and Look-Ahead)
Parameter #910-#914 (Axis Configuration)
Parameter #932 (User Macro / Graphics)
Introduction: The "Secret" Parameters of the Fanuc OT Control
The Fanuc OT (also written as Fanuc 0T) is one of the most iconic and widely used CNC controls for lathes and turning centers. Despite being introduced in the mid-1980s, thousands of machines worldwide still rely on this resilient, workhorse control.
While most operators are familiar with standard parameters (0000–8999), there exists a mysterious and often misunderstood range: Parameters 900 to 999.
Colloquially known as the "900 Parameters," or the "Option Parameters," this list holds the keys to your machine’s capabilities. Unlike standard settings that control axis tuning or I/O configuration, the 900 parameters enable or disable purchased options—features like rigid tapping, macro programming, AI contour control, and additional axes. fanuc ot 900 parameter list
This article provides an exhaustive breakdown of the Fanuc OT 900 parameter list, explaining what each bit does, how to access them, and critical precautions to take before making any changes.
| Bit | Name | Function | | :--- | :--- | :--- | | 0 | MA2 | Macro B (G65 with expressions, DO/WHILE loops) – Highly valuable | | 1 | GRA | Graphic display (tool path simulation on CRT) | | 2 | SPM | Spindle error detection (load meter, speed arrival check) | | 3 | PMV | Program mirror image (for dual turrets) | | 4 | PLF | Polygon turning (G77, G78) | | 5 | PS1 | Punch special codes 1 | | 6 | PS2 | Punch special codes 2 | | 7 | SHP | Shop floor programming (conversational) |
Parameters 900–949 (and sometimes up to 999 depending on the ROM version) are often called "Option Parameters" or "Hardware Configuration Parameters."
They are stored in SRAM (Static RAM) backed by a battery. If the battery dies, these parameters are lost—and the machine becomes a brick.
The 900 series does not control feed or speed. Instead, it controls:
Critical warning: Writing a random 900 parameter set from another machine of the same model will usually not work. These values are matched to the specific hardware and PMC ladder of your exact lathe.
| Bit | Name | Function | | :--- | :--- | :--- | | 0 | HSM | High-speed machining (look-ahead) | | 1 | RIN | Rigid tapping (G84.2 / G84.3) – Critical for live tooling | | 2 | PRC2 | Advanced precision contouring (improved block transition) | | 3 | F15 | F15 format part system | | 4 | LK3 | Helical interpolation (Z axis movement during circular interpolation) | | 5 | CX1 | Chamfering / corner rounding (G01 with ,C or ,R) | | 6 | PPB | Program re-start (from any sequence number) | | 7 | NC1 | NC unit for punching |
If you are staring at a blank screen or recovering from a dead battery: When people search for the 900 list, they
Do you have a specific issue you are trying to solve? (e.g., enabling rigid tapping, spindle orientation, or restoring a backup?) If you share the specific parameter number you are looking at, I can tell you exactly what that bit does
The FANUC 0T (Series 0) control is a legendary workhorse in the CNC world. However, when your memory backup battery fails or you need to unlock specific machine features, you inevitably run into the 900 series parameters.
These are the "Option Parameters" that govern the core capabilities of your machine. ⚙️ Understanding the 900 Series
Unlike standard parameters (like feed rates or offsets), the 900 series parameters are binary. Each parameter consists of 8 bits (0 or 1), where each bit acts as a "toggle" for a specific software option.
⚠️ Warning: Changing these without a backup can render your machine inoperable. Always document your original values before making edits. 🛠️ How to Enable Parameter Writing
Before you can modify any 900 series data, you must put the machine in a state that allows editing: Switch to MDI Mode. Press the PARAM/DGNOS button. Find the SETTING page. Change PWE (Parameter Write Enable) from 0 to 1. The machine will throw a "P/S 100" alarm—this is normal.
You can now navigate to the 900 parameters and make changes. 📑 Common FANUC 0T 900 Parameter List
While every machine is configured differently by the builder (OEM), here are the most common bit definitions for the 0T-A, 0T-B, and 0T-C controls: Parameter 900 Bit 0: Canned Cycles (G70–G76) Bit 1: G70-G76 Canned Cycles (alternate) Bit 2: Circular Interpolation (G02/G03) Bit 3: Sub-program calls (M98/M99) Parameter 901 Bit 1: Tool Geometry/Wear Offsets Bit 3: Custom Macro A Bit 6: Inch/Metric Conversion (G20/G21) Parameter 902 Bit 1: Constant Surface Speed Control (G96/G97) Bit 5: Background Editing Parameter 907 Bit 0: 48 pairs of tool offsets Bit 3: 64 pairs of tool offsets 📂 The Importance of the "Parameter Sheet" Parameter #904 / #905 (Buffer and Look-Ahead)
Every FANUC-controlled machine originally shipped with a paper Parameter Sheet (often tucked inside the electrical cabinet door). This sheet is the "DNA" of your specific lathe. If you lose your parameters due to a battery crash: Step 1: Locate that paper sheet. Step 2: Manually type in the 900 series first. Step 3: Power cycle the machine.
Step 4: Load the remaining parameters (0–800+) via RS232 or manual entry. 💡 Troubleshooting Tips
Parity Errors: If you get a "System Alarm" immediately after changing a 900 parameter, the control has detected an invalid configuration. Revert to the previous value.
Memory Limit: Some 900 parameters enable more "Programs Registered" or "Memory Length." Be careful not to exceed the physical RAM installed on your Master Board.
If you are looking for a specific bit to enable a feature like Rigid Tapping or Custom Macro B, let me know: The exact model (0T-A, 0T-B, or 0T-C?) The feature you are trying to unlock
Note: The exact map depends on the FANUC OT ROM version (A16B-2200, A16B-2300, etc.). Below is the most common standard for OT-C and OT-D.
Format: Parameters are usually displayed in binary (8 bits) from bit 7 (left) to bit 0 (right).
| Bit | Name | Function | | :--- | :--- | :--- | | 0 | HLP | Help function (on-screen assistance) | | 1 | SCH | Schedule program (multi-job management) | | 2 | TAP | Tape mode editor | | 3 | LDP | Load / unload parameter (PMC ladder transfer) | | 4 | MDC | Manufacturing data capture (production counters) | | 5 | DRV | Driver monitor (servo waveform display) | | 6 | PRT | Parameter trace (diagnostic logging) | | 7 | ALM | Alarm history storage |