Unlike other parameters, the 9900 series is not typically listed in the standard "Parameter Manual" provided by Fanuc. Instead, these settings are usually documented in the Machine Tool Builder’s Manual (e.g., Makino, Mori Seiki, Haas, etc.).
The reason for this secrecy is simple: Risk.
If you change a standard parameter incorrectly, you might get an alarm or a crash. If you change a 9900 parameter incorrectly, you can instantly disable the control, make the screen go blank, or wipe out critical system options. Because these parameters configure the core hardware communication, the control may not even know how to boot up properly if they are altered. fanuc 9900 parameter list
Controls whether Profibus, DeviceNet, EtherCAT, or Fanuc I/O Link i is active.
In Fanuc controls (specifically Series 16, 18, 21, 16i, 18i, and 21i), the 9900 parameter range is reserved for System Configuration and Option Activation. Unlike other parameters, the 9900 series is not
Think of the 9900 parameters as the "master keys" to the control. While standard parameters determine how the machine moves (speeds, feeds, accelerations), the 9900 parameters determine what the machine is capable of doing.
If your machine does not rigid tap (no floating tap holder required), check: Controls whether Profibus, DeviceNet, EtherCAT, or Fanuc I/O
Fanuc intentionally restricts access to parameters 9900–9999. On most controls (Series 0i, 15i, 18i, 21i, 30i, 31i, 32i, and 35i), you must:
Why? Because the 9900s are not tuning parameters—they are configuration parameters. An incorrect entry can:
Always back up your existing parameters before touching the 9900 range.
