Fanuc Parameter 1860 (2024)

APC (Absolute Pulse Coder)

It was a late Tuesday shift at the machine shop when the lights flickered and the old Fanuc-controlled mill went dark. When the power finally hummed back to life, the operator didn't see the usual ready screen. Instead, a series of alarms blinked in angry red—the backup batteries had finally given up, and the machine had "forgotten" where it was.

Solution:

First, ensure mechanical freedom (check belt, bearings, drawbar). Then increase 1860 gradually. fanuc parameter 1860

| Problem | Likely Cause | Solution | |---------|--------------|----------| | Alarm PS0090 after G28 | 1860 too high → missed marker pulse | Reduce 1860 by 50% and retest. | | Intermittent home position shift (5-20 microns) | 1860 borderline high + electrical noise | Lower 1860; also check encoder cable shielding. | | Axis overtravels immediately after dog detection | 1860 higher than rapid speed (1420) | Set 1860 < 1420. | | Rotary axis homes inconsistently | 1860 too high for rotary inertia | Reduce 1860; consider increasing deceleration time (Parameter 1620). | | Homing takes >5 seconds | 1860 too low | Increase 1860 (test stability first). | APC (Absolute Pulse Coder) It was a late

high-speed reference return

Some high-end FANUC controls (31i-B5, 30i-B) offer an optional that bypasses the dog entirely. In that mode, Parameter 1860 is ignored. However, standard dog-type return remains the default. Parameter 1860 is a critical

2-word (32-bit) axis parameter

Parameter 1860 is a . Its primary function is to maintain the absolute position data provided by the encoder. When a machine uses an absolute encoder, it doesn't need to be "homed" or "zero-returned" every morning; instead, it reads the value stored in this parameter to determine its exact location.

  • Default/typical range: Manufacturer defaults vary by machine model and drive — common values are between 50–500 RPM for many lathes/mills.
  • Setting advice:

    In the world of FANUC CNC systems, Parameter 1860 is a critical, though often misunderstood, data field that serves as the digital link between the machine's physical location and its internal coordinate system. For technicians and engineers, mastering this parameter is essential for maintaining the high-precision "memory" of a machine tool. The Role of Absolute Position Detectors