A "full" or correct setting ensures the reference counter exactly matches the number of position feedback pulses in one motor revolution.
| Encoder Type | Reference Pulses/Rev | Typical 1820 | Calculated 1860 | |--------------|----------------------|--------------|------------------| | αiA 4096 P/rev | 4096 | 4096 | 1 | | αiB 16384 P/rev | 16384 | 16384 | 1 | | αiCZ 10000 P/rev | 10000 | 10000 | 1 | | βiA 8000 P/rev | 8000 | 8000 | 1 |
If 1860 = 1, the counter capacity equals the number of feedback pulses per motor revolution. This is the most common "full" setting. Values >1 are possible but rare; they effectively shorten the counter range, which can cause reference point shift issues.
Parameter 1860 (Movement Pulse) is a critical servo initialization parameter. It defines the distance the machine axis moves for every single pulse of feedback emitted by the encoder or scale. Essentially, it establishes the mathematical relationship between the electrical pulses detected by the CNC and the physical mechanical travel of the axis.
An incorrect setting in Parameter 1860 will result in the machine moving an incorrect distance (e.g., commanding 100mm but moving 50mm or 200mm), rendering the machine unable to perform accurate machining or threading.
Fanuc Parameter 1860 is not a "set and forget" value. It is a dynamic tuning lever that balances the competing demands of speed (cycle time), accuracy (corner fidelity), and stability (vibration-free cutting).
The best approach is systematic: start with the machine builder's recommendation, use the acceleration formula to find a theoretical minimum, test with a representative part, and adjust in small increments. By mastering Parameter 1860, you unlock the true performance potential of your Fanuc CNC—moving from a machine that just "runs" to one that runs efficiently, accurately, and reliably.
Final Pro Tip: Regularly review Parameter 1860 as part of your preventive maintenance schedule. After six months of heavy use, ballscrew wear can change the system's inertia, and a once-perfect 1860 value may need a 10-20% increase to maintain smooth motion.
References: Fanuc 0i-D, 0i-F, 31i-B5 Series Connection Manual (B-64643EN) and Parameter Manual (B-64640EN). Always consult your specific machine tool builder's documentation as they may override standard Fanuc recommendations with custom PMC logic or secondary parameters.
In FANUC control systems, Parameter 1860 is specifically used to define the current position of an axis when using an Absolute Position Detector
. This parameter is part of the axis-specific settings (1800-series) and is critical for maintaining machine coordinates without needing a reference return (homing) every time the power is cycled. Key Function & Usage
: It stores the absolute position data for each controlled axis. Absolute Encoders : This parameter works in conjunction with Parameter 1815 (specifically the
bits), which tells the system that an absolute pulse coder is being used and whether the reference position has been established. Coordinate Synchronization
: When the machine is powered on, the CNC reads the value from the absolute encoder and reconciles it with the value stored in Parameter 1860 to determine the exact machine position. Common Technical Scenarios Battery Failure
: If the backup battery for the absolute pulse coder dies, the data in Parameter 1860 may become invalid. This often results in a 300-series alarm (e.g., APC Alarm: Reference Return Required).
: A common error associated with this parameter is "Alarm 309: Reference Return Impossible," which typically occurs if you attempt to set the reference position (APZ bit in 1815) before the system has properly recognized the encoder data or if there is a mismatch with Parameter 1860. Homing After Battery Swap
: After replacing batteries, you must typically move the axis to the physical home position and toggle Parameter 1815 (APZ) to "1" to update Parameter 1860 with the new zero-point data. How to Modify (If Required) To change axis parameters like 1860, you must first enable Parameter Write Enable (PWE) [OFFSET SETTING] PARAMETER WRITE and change the value to
The control will issue a "100 PARAMETER WRITE ENABLED" alarm; this is normal. Navigate to [PARAMETER] , and press to find the specific axis values.
Incorrectly modifying Parameter 1860 can cause the machine to "lose" its position, potentially leading to crashes if the software limits no longer align with the physical machine limits. Are you currently dealing with a specific alarm code (like 300 or 309) after a battery change? How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
Fanuc Parameter 1860 is primarily used to set the backlash acceleration amount in specific control series like the Fanuc 15i. In other common series (such as 16i, 18i, and 21i), this function is often mapped to parameter 2048 instead. Key Details for Parameter 1860 (Backlash Acceleration)
Function: It defines the amount of offset added to the velocity command immediately following a reversal in axis direction to compensate for mechanical backlash. Typical Setting Range: 20 to 600. Related Parameters:
1861 (15i) / 2071 (16i/18i/21i): Defines the time period (usually in 2ms units) that the backlash acceleration remains effective.
2003 bit 5 (16i/18i/21i): Known as BLEN, this bit must be set to 1 to enable backlash acceleration functions. Commonly Confused Parameter: 1815
Users searching for "1860" in the context of absolute encoders or home positions are often actually looking for Parameter 1815, which is critical for resetting axis reference positions.
1815 Bit 4 (APZ): Indicates if the reference position (zero point) is established. If it is 0, a 300 APC alarm occurs.
1815 Bit 5 (APC): Specifies whether an absolute pulse coder is used for that axis. How to Change Parameters
To modify these or any other system parameters, follow these steps: How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
Important safety notes:
How to confirm exact definition for your controller: fanuc parameter 1860 full
If you tell me your exact Fanuc control model and software version (for example "Fanuc 0i-MF v9.07" or "Fanuc 21i-TB"), I will give the exact definition and permitted values for parameter 1860.
The Ghost in the Machine: Understanding Fanuc Parameter 1860
In the world of high-precision CNC machining, the Fanuc 1860 parameter occupies a unique and somewhat mysterious position. While many common parameters like 1851 (backlash compensation) are frequently adjusted by technicians, Parameter 1860 is often described as an "untouchable" or "read-only" value that provides a fascinating look into the machine's internal logic. The Digital Pulse: What is Parameter 1860?
At its core, Parameter 1860 functions as a current absolute position counter for a given axis. In many Fanuc systems, this parameter displays a raw value representing the absolute position of the axis as reported by the encoder.
Unlike coordinate offsets that an operator can easily manipulate, Parameter 1860 is deeply tied to the Absolute Position Detector (APC). It often uses "modular arithmetic," meaning the value will "wrap around" as the axis moves through its full range of motion. The Lifecycle of the Value
The value in Parameter 1860 is not static. It is automatically updated by the system in several critical moments:
Initial Referencing: When an axis is "zeroed" or re-homed using Parameter 1815 (APZ bit), the system recalculates and updates the value in 1860.
Real-Time Feedback: As the servo motors move, the 1860 value fluctuates to reflect the continuous stream of data coming from the pulse coders. Why It Matters to Technicians
While you cannot "manually" set Parameter 1860 to a specific number to fix a machine, observing it is a powerful diagnostic tool.
Diagnostic Troubleshooting: If a machine experiences a Z-axis "drop" during an E-stop, technicians can check the change in Parameter 1860 to see exactly how much the axis moved before the mechanical brake engaged.
Verifying Encoder Health: Sudden jumps or inconsistent "wrap-around" behavior in this parameter can signal a failing encoder or noise in the communication line between the motor and the CNC control. Safety and Modification
Official documentation, such as the Fanuc Parameter Manual, warns that these low-level servo parameters are "intellectual property" of the manufacturer and should not be modified without expert knowledge. Misconfiguring these can lead to "illegal servo parameter" alarms or, worse, mechanical crashes.
In essence, Parameter 1860 is the machine’s internal "truth"—a raw digital heartbeat that tells the system exactly where it is in the physical world, long before those numbers are translated into the user-friendly coordinates we see on the screen.
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.
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
Understanding Fanuc Parameter 1860: Absolute Position Detection
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? A "full" or correct setting ensures the reference
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
Fanuc Parameter 1860 is a critical axis-specific setting used to store and manage the absolute position data for machines equipped with absolute pulse coders. It works in tandem with Parameter 1815 to ensure the CNC control "remembers" its exact physical location, even after power cycles, eliminating the need for manual zero-return (homing) operations every morning. Core Function and Purpose
The primary role of Parameter 1860 is to hold the coordinate value that aligns the machine's physical position with the feedback from the absolute encoder.
Absolute Position Storage: It records the current position of each axis relative to the reference point.
Reference Maintenance: When the machine is powered off, the absolute encoder (supported by a battery) keeps track of movement. Upon power-up, the control compares this data with Parameter 1860 to restore the absolute coordinate system immediately.
Rotation Handling: For rotary axes, Parameter 1860 is used to manage the 0-degree or rounding values (e.g., 360 degrees) to ensure the position updates correctly as the axis rotates. The Relationship Between Parameter 1860 and 1815
You cannot effectively manage Parameter 1860 without understanding Parameter 1815, as they are the two halves of the absolute positioning system.
Parameter 1815.4 (APZ): This bit indicates if the reference position for an axis has been established (1 = established, 0 = not established).
Parameter 1815.5 (APC): This bit determines if an absolute position detector is being used for that axis (1 = absolute, 0 = incremental).
Automatic Updating: In standard procedures, manually performing a reference return after setting 1815.4 to '0' will cause the CNC to automatically update the value in Parameter 1860 and then flip 1815.4 back to '1'. How to Set or Reset Parameter 1860
If you encounter a "300 APC Alarm: Need ZRN" (Zero Return Needed), typically caused by a dead battery, you must re-establish the relationship between the physical machine and the encoder data. How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
On a Fanuc CNC system, Parameter 1860 (also known as GRIDX) is a critical axis-specific setting used to define the grid shift amount for the reference position (home position).
This parameter is typically used during machine setup or maintenance to fine-tune the machine’s zero point without physically moving the limit switches or reference cams. Quick Breakdown of Parameter 1860
Function: Adjusts the electrical reference position by a specific number of pulses (detection units). Data Type: 2-word (Signed long integer).
Unit: Detection units (the smallest increment the machine can move).
Applicability: Essential for systems using incremental or absolute pulse coders where the "Grid Method" is used for zero return. Why Adjust Parameter 1860?
You would change this value if your machine’s home position is physically "off" by a small, consistent amount. Instead of re-mounting a cam or switch, you enter a "shift" value here to tell the control where the true zero is relative to the first grid pulse it detects. How to Set It
Enable PWE: Put the machine in MDI Mode. Go to the SETTING page and set PARAMETER WRITE (PWE) to 1. (Note: This will trigger a P/S 100 alarm, which is normal).
Find the Parameter: Press the SYSTEM hard key, then the PARAM soft key. Type 1860 and press NO. SRH.
Enter the Value: Select the axis you want to adjust (X, Y, Z, etc.) and input the new value.
Positive values shift the reference position in the positive direction. Negative values shift it in the negative direction.
Restart: For the changes to take effect, you must cycle the power of the machine.
Disable PWE: After rebooting, set PARAMETER WRITE back to 0 and press RESET to clear the alarm. Pro-Tip: The Grid Shift Limit If 1860 = 1 , the counter capacity
Be careful not to set a value larger than the grid reference distance (the distance between two encoder "grid" pulses). If the shift is too large, the machine might skip a grid and home to the wrong position entirely.
Need help calculating the exact shift value for your specific axis? How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
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).
Function: It tracks the absolute position of each axis. This value is automatically set and updated by the CNC when an axis is zeroed (specifically through Parameter 1815 APZ).
Usage: Maintenance technicians use this parameter to verify that the absolute pulse coder is correctly tracking the machine's physical position.
Modular Arithmetic: The value may "wrap around" based on the encoder's count limits, which is normal behavior for absolute detectors. Related Reference Parameters
When troubleshooting absolute position issues, you will likely need to check these associated parameters:
Parameter 1815: Used to set the absolute position reference (Bit 4: APZ).
Parameter 1850: Sets the grid shift amount to fine-tune the zero position. Parameter 1851: Controls backlash compensation. Safety Note
Do not attempt to force a value into Parameter 1860. On most systems, it is read-only. To change the machine's reference position, use the proper zero-point setting procedure involving Parameter 1815.
Are you experiencing a specific alarm code or axis shift that led you to check this parameter? 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!
Parameter 1860 is a bit-datalen (axis-specific) parameter used to define the checking distance for the reference position return operation.
On many FANUC controls, Parameter 1860 works in conjunction with Parameter 1850 (grid shift) and Parameter 1851 (reference position shift). It determines the range (travel distance) the axis must move to verify that it has correctly reached the machine's reference (home) position after a deceleration signal from the deceleration dog.
WARNING: Changing servo parameters can cause axis runaways or crashes. Clear the machine work zone and be prepared to hit E-STOP immediately.
When users search for "full," they often mean one of two things:
Unlike a macro variable, a parameter cannot be "full" in the sense of being filled to capacity. Instead, the term implies you need to understand the complete range of values (-99999999 to +99999999 in most Fanuc controls) and how to determine the exact number to input.
If the absolute encoder battery dies, the machine loses its zero position. After replacing the battery, you must re-establish machine zero. Parameter 1860 allows you to "tell" the control where the new zero is relative to the mechanical hard stops.