Fanuc Parameter 1860 Here
| 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). |
If Parameter 1860 is set too low, the machine accelerates violently. This puts immense stress on the ballscrews, thrust bearings, and servo motors. Over time, this leads to premature mechanical failure, reversed backlash, and accuracy issues. fanuc parameter 1860
No parameter exists in isolation. 1860 works in concert with several others: | Problem | Likely Cause | Solution |
| Parameter | Function | Relationship with 1860 | |-----------|----------|------------------------| | 1420 | Rapid traverse speed (G00) | Must be > 1860. High-speed approach uses 1420 until dog detection. | | 1424 | Manual feedrate (JOG) | Independent, but 1860 is automatically used during JOG reference return. | | 1430 | Maximum cutting feedrate (G01) | Clamps 1860 if 1860 > 1430 (alarm occurs). | | 1850 | Grid shift amount | No direct speed relationship, but both affect final reference position. | | 1851 | Reference position shift (fine) | Fine offset after grid detection; 1860 influences repeatability of this shift. | | 1006#5 (ZMIx) | Reference return direction | 1860 speed applies in the direction set by ZMI. | | 1815#4 (APZx) | Reference position establishment | APZ must be set after tuning 1860. | On these legacy systems:
| Condition | Symptom | Root Cause | |-----------|---------|-------------| | 1860 too high (e.g., 2000 mm/min on a linear axis) | Axis slams into dog, overshoots reference point, inconsistent home position ± several encoder counts. May trigger overtravel alarm after homing. | High inertia prevents motor from stopping precisely on the marker pulse. | | 1860 too low (e.g., 30 mm/min) | Homing takes excessively long (10-20 seconds per axis). No immediate error, but wasted cycle time. | Creep speed is unnecessarily slow—the marker detection is reliable at moderate speeds. | | 1860 optimal (typical: 100-600 mm/min) | Fast, consistent reference return. Home position repeatable within 1 micron. | Speed allows motor to stop within one encoder count (or fractional count for serial pulse coders). |
The PMC (Programmable Machine Controller) can override reference return speed in some custom cycles. Check ladder rungs referencing address G100 (reference return speed selection). If PMC forces a different speed, Parameter 1860 becomes secondary.
On these legacy systems: