Fanuc Ot 900 Parameter List May 2026

Note: Fanuc OT has multiple ROM versions (A, B, C, D, Mate). The exact function of each bit can vary. This list reflects the most common standard for Fanuc OT-B and OT-C.

1. Never rely on screenshots alone. The Fanuc OT 900 parameter list varies by:

2. Backup before editing.
Old Fanuc OT controls have volatile CMOS batteries. Use the PUNCH function to output all parameters to a PC: fanuc ot 900 parameter list

EDIT mode → PUNCH → ALL PARAMETERS → EXEC

Save the file. Specifically, save the 900 range (N900–N999).

3. Do not "experiment" with 908 and 909.
Setting 908 incorrectly can cause a "System HALT" requiring a ROM replacement. Setting 909 without the proper option key may lock the control permanently.

4. Understand the "Parameter Number Changed" alarm.
If you change a 900 parameter and get a "P/S 000" alarm with "PLEASE TURN OFF POWER," you must cycle the control fully. Some 900 bits require a cold start.

5. Legal note:
Enabling an option via the 900 parameter list that you did not purchase may violate your license agreement with Fanuc. However, if your machine label shows "Macro B included" but it’s disabled, you have every right to re-enable it.

Want to check yours? On a Fanuc OT, press DGNOS/PARAM → soft key right to PARAM → type 900 → INPUT. If you see zeros for everything, someone never set them – or you’ve just had a memory loss.

This is a guide to the Fanuc Series 0-T (Model T) parameter list, specifically focusing on the critical 900-series parameters.

⚠️ CRITICAL WARNING: Incorrect settings in the 900-series parameters can render the machine inoperable, cause servo crashes, or result in dangerous rapid movements. Always back up parameters before making changes. Do not alter these unless you are a qualified service engineer or have specific instructions from the machine tool builder.

In the Fanuc OT architecture, parameters 900–909 (and sometimes up to 919, depending on the CNC version) are stored in a protected area of the CNC’s non-volatile memory (CMOS). They are not backed up by the standard battery-backed RAM. Instead, they are tied to the CNC’s firmware.

| 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 | Fanuc 0T has several versions:

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.

| Bit | Function | |------|-----------| | 7 | DNC drip-feed baud rate override | | 6 | Remote buffer (32K) enable – required for complex programs | | 5 | High-speed serial (RS-422/RS-232C) | | 4 | Tape mode without parity check | | 3-0 | Communication protocol version |