A 4th or 5th axis rotary table has high inertia. Setting 1860 too low on the rotary axis will cause "clunking" on start/stop. Fix: For a rotary axis, start with 1860 = 150 ms. Increase until motion is smooth, even if it slows indexing.
Fanuc Parameter 1860 is defined as the Reference Position Shift Value on the Z-axis (or the axis to which it is assigned). In many standard Fanuc configurations (especially on lathes and machining centers with absolute encoders), Parameter 1860 holds the distance (in detection units) that the machine moves to find its Grid Point during a reference return operation.
To understand 1860, we must first understand the Grid Method. When you perform a Zero Return (often written as G28 or manually pressing the reference return button), the machine does not simply "know" where zero is. Instead, it moves toward a Deceleration Dog (physical limit switch). Once it hits the dog, the axis decelerates and searches for the first "Grid Point" of the servo motor's encoder. Parameter 1860 tells the control to shift that Grid Point by a specific amount.
After replacing a servo motor or ballscrew, the machine shakes during G01 moves. Fix: The new components have different inertia. Calculate the new inertia ratio (parameter 2047/2048) first, then reduce 1860 by 20% as a starting point, then fine-tune upward.
In Fanuc CNC systems (such as the Series 0 Parameter 1860 stores the Absolute Position Detector (Encoder) offset
. This value represents the amount of shift required to align the absolute encoder's internal reading with the machine's actual reference position. Key Functions & Characteristics
: It acts as the "calibration" value for an absolute encoder. When you perform a zero-return or "homing" procedure on a machine with absolute encoders, the system calculates the difference between the encoder's current reading and the physical home position, then saves this value in Parameter 1860. Automatic Updates : Typically, you do manually enter a value here. When Parameter 1815
bits (APC and APZ) are toggled to set a new home position, the CNC automatically calculates and populates Parameter 1860. : It is an axis-specific parameter, meaning each axis ( , etc.) has its own unique 1860 value. en.industryarena.com Common Maintenance Scenarios Reference Position Loss
: If the absolute encoder batteries die or the encoder cable is disconnected, the relationship between the mechanical position and the encoder data is lost. Re-establishing the home position will result in a new value being written to Parameter 1860. Grid Shift Correlation Parameter 1850
handles small mechanical "grid shifts" for fine-tuning, Parameter 1860 handles the primary data offset for the absolute detector. Tool Change Alignment : On some machines, if the
-axis home position is reset, the value in 1860 changes, which may require you to re-verify the tool change height stored in Parameter 1241 en.industryarena.com How to View/Set Enable Writing : In MDI mode, go to the screen and set PARAMETER WRITE = 1 : Press the hard key, then the to locate the parameter for each axis.
: Manual modification is rare and usually only done during advanced troubleshooting or when migrating parameters from a backup. cti-sumy.com.ua Are you currently troubleshooting a 300 APC Alarm (Ref Position Need Return) or have you recently replaced encoder batteries 64120EN 0i Parameter Manual.pdf
In Fanuc CNC systems, Parameter 1860 is specifically used to define the current position (or absolute position) of each axis when using an absolute pulse coder. Function of Parameter 1860
This parameter stores the absolute position of the machine's axes relative to the machine zero point. It is primarily relevant for machines equipped with absolute encoders, where the position must be retained even after the power is turned off.
Role: It acts as the reference for the absolute position in the machine coordinate system.
Data Type: It is typically a 2-word (long integer) axis-specific parameter. fanuc parameter 1860 full
Relationship with 1815: It works in conjunction with Parameter 1815, specifically bit 4 (APZ), which indicates whether the absolute position has been established (1 = established, 0 = not established). When to Modify Parameter 1860
You generally do not manually edit Parameter 1860 during standard operations. It is typically updated by the CNC system automatically during the Reference Position Setting procedure. Modification is usually only necessary during:
Encoder replacement: When a new absolute pulse coder is installed.
Battery failure: If the backup battery for the absolute pulse coder dies, causing the machine to lose its zero position.
Mechanical repairs: After significant mechanical work that shifts the physical relationship between the motor and the machine's home position. Accessing the Parameter To view or set this parameter, follow these steps: How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
In Fanuc CNC systems, Parameter 1860 is a read-only axis parameter that stores the current position of the absolute position detector (absolute encoder). It is often referred to as the current position in the absolute detector or the "encoder count". Technical Overview
: It tracks the raw position data from the absolute pulse coder. Unlike coordinate parameters you can manually edit (like 1240 for reference positions), this parameter is updated automatically by the system. : It is typically a 2-word axis parameter (long integer).
: The value is established after an axis is successfully zeroed using Parameter 1815.4 (APZ)
. If the axis has dropped (e.g., a Z-axis droop during emergency stop), this value may reflect that physical shift even if the machine's relative position display was reset. Key Related Parameters
To understand how 1860 fits into the system, it is usually viewed alongside these coordinates and flags: Parameter 1815
: Used to set the absolute position detector (APC) and the zero position (APZ). Setting is what initializes the value in 1860. Parameter 1240–1243
: These define the coordinate values of the 1st through 4th reference positions in the machine coordinate system. Parameter 1850 : Often confused with 1860, this is the Grid Shift
value used to adjust the zero point after a reference return. Maintenance & Troubleshooting Read-Only Nature
: Users generally cannot change 1860's value manually in a "meaningful way" because it is a direct feedback value from the hardware. Axis Droop
: In machines without counterweights, a spindle may droop during an E-stop before the brake engages. Parameter 1860 will record this displacement, which can lead to slight discrepancies in homing if not accounted for. Zeroing Procedure A 4th or 5th axis rotary table has high inertia
: If you replace an absolute encoder or lose your home position, you must set
, cycle power, move to the physical home, and set it back to
. This process "syncs" the mechanical position with the value now stored in 1860. For detailed technical specifications, refer to the Fanuc Series 0i-MODEL F Plus Parameter Manual Series 16i/18i Parameter Manual using these parameters? FANUC? M6 toolchange position. | Practical Machinist
A very specific question!
In FANUC CNC systems, parameter 1860 is related to the "Long Piece" or "Long Part" function, which allows for machining of long workpieces that exceed the standard travel limits of the machine.
Here's a brief overview:
Parameter 1860: Long Piece (Full)
To set parameter 1860, you typically need to:
Example:
If you want to enable the Long Piece function, you would set parameter 1860 to 1:
1860 = 1
After setting the parameter, be sure to save the changes and restart the machine, if required.
Keep in mind that incorrect parameter settings can lead to machine malfunction or safety issues. Always consult the FANUC documentation and/or contact a qualified FANUC technician if you're unsure about setting parameters.
Do you have a specific FANUC CNC machine model or control system version you're working with? I'd be happy to help if I can!
Understanding Fanuc Parameter 1860: Absolute Position Detection To set parameter 1860, you typically need to:
Fanuc Parameter 1860 (often referred to as APZ) is a critical configuration setting in Fanuc CNC systems (such as the Series 0i, 16i, 18i, and 31i) that indicates whether the reference position for an absolute pulse coder has been established for a specific axis.
When a machine is equipped with absolute encoders, it does not require a manual "home" or zero-return operation every time it is powered on, provided the absolute position is correctly saved. Parameter 1860 is the system's "flag" that tells it whether this position is currently valid. 1. The Core Meaning of Parameter 1860
Parameter 1860 is a bit-type parameter where each bit typically corresponds to a different controlled axis (X, Y, Z, etc.).
0: The reference position is not established. The machine does not know its absolute zero, and you will likely see a "Need ZRN" (Zero Return) alarm or a 300-series absolute pulse coder alarm.
1: The reference position is established. The system knows exactly where the axis is located based on the absolute encoder data. 2. When Does Parameter 1860 Revert to 0?
In a perfectly functioning machine, this parameter stays at "1" indefinitely. However, certain events will force it to "0," requiring a re-homing procedure:
Battery Failure: Absolute encoders rely on a backup battery to "remember" their position when the power is off. If the battery dies, the position is lost.
Encoder Disconnection: Unplugging the encoder cable or replacing the motor/encoder resets the stored position.
Mechanical Overhaul: If you disconnect the motor from the ball screw, the physical relationship between the encoder and the machine zero changes.
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
If you encounter an absolute pulse coder alarm (like Alarm 300), you must re-establish the reference position. Simply typing "1" into Parameter 1860 is usually not enough; the CNC must "see" the machine reach its physical home first. Step-by-Step Recovery Procedure: How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
If the motor turns a different speed than the screw (e.g., Motor turns 2 times for 1 turn of the screw):
Your Fanuc servo system operates on a "Grid" generated by the position feedback device (pulse coder, absolute encoder, or scale). As the motor rotates, the encoder sends pulses. The control identifies a specific pulse as the "Grid Point" – a reproducible position for machine zero.
When you adjust Parameter 1860, you are not moving the physical limit dog. You are electronically shifting where the control thinks the grid point is.
The formula is conceptual:
Final Grid Position = Natural Grid Point + Value(Parameter 1860)
In semi-closed loop systems, the CNC counts feedback pulses from the motor encoder to determine position. When returning to a reference point (grid method), the reference counter counts pulses from a grid signal until it reaches the value set in 1860, then generates the reference point.
In simpler terms: