Fanuc Ot 900 Parameter List May 2026

The Ultimate Guide to the FANUC OT 900 Parameter List: Diagnostics, PMC, and System Recovery

Parameter 903 – Advanced Macros & Graphics

| 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) |

Introduction

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. fanuc ot 900 parameter list

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. The Ultimate Guide to the FANUC OT 900

2. How to Access 900 Parameters

On the Fanuc 0-T, these parameters are often hidden or write-protected.

Step 1: Enable Parameter Write

Select MDI Mode or Emergency Stop.
Find the Program Protection Key on the operator panel (sometimes labeled "PWE" or locked behind a door). Turn it to the "Write" or "Unlocked" position.
On the control keypad, press the OFFSET (or SETTING) button until you see the SETTING screen.
Move the cursor to PWE (Parameter Write Enable).
Type 1 and press INPUT. An alarm (usually Alarm 100 or 000) will appear. This is normal; it indicates parameters can be changed.

Step 2: Access the Screen

Press the PRM (Parameter) button.
Type 900 and press INPUT or SEARCH.
If the screen shows "0000" or blanks, the parameters are often hidden behind a specific search number. On many OT controls, you must view them via the System Parameter screen, often accessed via the SYSTEM soft key (sometimes DGNOS/PARAM).

Step 3: Restart Requirement After changing any 900-series parameter, you MUST cycle power (turn the control off and on) for the change to take effect. Select MDI Mode or Emergency Stop

Method 1 – Manual Recording

Print or manually write down all parameters from 000 to 999 (yes, all).
Pay special attention to 900–949. Copy them as an 8-character string per param.
Store in two places: the machine’s electrical cabinet and a cloud drive.

Why You Need the Fanuc OT 900 Parameter List

Here are three real-world scenarios where the 900 parameter list is invaluable:

Recovering from a Lost 900 Parameter List – Step-by-Step

If your battery died and you have no backup, attempt this recovery sequence:

Find a machine twin: Same model, same year, same options. Copy its 900–949 parameters blindly? No—but cross-reference.
Enter safe defaults: Set param 900 = 10001000 (X & Z only), param 901 = 00000000 (spindle no special options), param 902 = 01000000 (PMC-R default).
Check PMC I/O mapping: Diagnostic DGN 300–315 will show I/O signals; if turret doesn’t index, your param 908 is wrong.
Contact the builder: Many (Mori, Okuma, Hardinge) still provide factory 900 parameter sheets for a fee.
Use FANUC Boot System: Hold - and . while powering up → enter boot menu → load from PCMCIA if a backup exists.