Fanuc Parameter: 1860 Full ^hot^

Fanuc Parameter 1860 (Position of the absolute position detector) is a read-only parameter that displays the current position value from the absolute pulse coder. While it is not a setting you typically edit manually, it serves as a critical reference point for the CNC system to maintain axis alignment without needing to re-home after a power cycle. Key Characteristics and Function Data Type: 4-word (integer).

2. 1860 Value Too High (Too Conservative)

Symptoms:

• On lathes, Parameter 1860 is critical for spindle-sync cutting. An incorrect value will cause the Z-axis feed rate to mismatch the spindle rotation, resulting in stripped or improperly pitched threads.

• Servo Lag Alarm (P/S 411 or 414): The actual position lags behind the command because the motor cannot accelerate fast enough for the required torque.
• Mechanical Vibration/Resonance: High-frequency noise during cornering or arc moves.
• Poor Surface Finish: Chatter, especially in corners or on shallow ramps.
• Motor Overheating: The servo works too hard to overcome inertia.

Note: Always refer to your specific FANUC maintenance manual (B-63944EN, B-63525EN, etc.) as parameter mapping and bit assignments can vary between series and firmware versions. fanuc parameter 1860 full

• Parameter 1860 still functions but interacts with 1850.
• Parameter 1850 sets the time constant for jerk limitation (rate of change of acceleration).
• Rule of thumb: If using bell-shaped ACC/DEC, set 1860 to 1.5–2x the value you would use for linear ACC/DEC.

9. Troubleshooting Checklist for 1860

• ❌ Alarm 90 (REF RETURN ALARM) → reduce 1860 by 30–50%.
• ❌ Inconsistent reference position after power-up → increase 1860 slightly (if dog length permits).
• ❌ Machine bangs at reference point → 1860 too high for deceleration curve; lower value or check axis acceleration parameters (1620, 1622).
• ✅ Optimal behavior: Axis approaches reference dog at 1860 speed, then decelerates smoothly to zero at exact reference position.

Manual Reset: A technician may manually change this bit to "0" to force a new home position calibration. 3. How to Set or Reset Parameter 1860 Fanuc Parameter 1860 (Position of the absolute position

Typical Default Setting:Most manufacturers set this between 20 and 100 ( On lathes, Parameter 1860 is critical for spindle-sync