Fanuc Parameter 1860 ((hot)) Guide

Key in the designated value according to your machine tool builder's documentation (typically 1 for standard absolute serial encoders). Press the softkey. Step 4: Power Cycle the Machine

[Direction Reversal] ---> [Mechanical Backlash Gap] ---> [Axis Latency / Stall] | (Parameter 1860 Intervention) v [Injected Acceleration Boost] | v [Seamless Motion & No Surface Bumps] At this reversal point, two phenomena occur:

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The confusion surrounding Parameter 1860 highlights a bigger issue in CNC maintenance: the critical need for proper documentation. Always keep: fanuc parameter 1860

Modifying parameters on a FANUC control must be done with caution. Errant keystrokes can cause machine crashes. Follow this procedure precisely: Step 1: Enable Parameter Writing Press the mode button on the operator panel. Press the OFFSET/SETTING function key. Locate the SETTING screen. Move the cursor to PARAMETER WRITE (PWE) .

“It’s just a parameter,” Gary said, for the fourth time. “You’re the expert.”

Because parameter 1860 acts as a memory register for the physical position of the encoder, it will update automatically during specific service actions: Key in the designated value according to your

Marina didn’t answer. Parameters were numbers. Numbers were easy. But this machine had a history—previous crashes, a motor swap from a donor machine, and a maintenance log written in disappearing ink.

Gary clapped her on the shoulder. “See? Just a parameter.”

Whenever you deal with encoder issues or motor replacements, keep your machine tool builder's master parameter sheet handy, and always back up your parameters before making any structural changes to the 1800-series parameter blocks. This link or copies made by others cannot be deleted

When a rotary axis with an absolute position detector passes through 0 degrees or reaches the shift value per rotation (360 degrees or the value set in parameter 1260), the reference position data stored in parameters 1860 and 1861 is automatically renewed. This renewal ensures that the control system can accurately follow the machine position when power is restored.

When the FANUC control boots up, it reads to see what kind of hardware is attached. It then checks Parameter 1815 Bit 5 to see if it should process that hardware as an absolute system. If both match, it checks Parameter 1815 Bit 4 to verify if the saved position coordinates are valid or if the machine requires a zero-point calibration. Common Scenarios Requiring Parameter 1860 Adjustments

Another user reported a problem where after homing, the Z-axis position always displayed "11.8311" instead of zeroing out. The forum solution involved checking Parameter 1240, which holds the coordinate value of the reference position, not Parameters 1860 or 1861. This is a crucial distinction: Parameter 1240 defines the coordinate of the reference point, while 1860/1861 store the absolute position value of that point from the encoder. As one expert pointed out, "Machine Home Position and Machine Zero Position are usually not the same point". Adjusting Parameter 1240 to 0 would make the machine read zero when homed, but this will shift all work and tool offsets.

To understand why Parameter 1860 is so critical, you must understand the difference between the two primary types of feedback loops:

For rotary axes using a scale without rotary data (such as Heidenhain RCN723 or Futaba FRR902L3DB rotary scales), the reference position data stored in parameters 1860 and 1861 does not need to be renewed. This is because scale data without rotary data is always read when the system is powered on, providing immediate position information.