Parameter 1860 (often referred to as ) is a non-editable, read-only system value that represents the absolute position (encoder count) of a machine axis. This parameter is central to how a CNC system "remembers" its location without requiring a home return (homing) every time it is powered on. The Function of Parameter 1860
In Fanuc control systems, Parameter 1860 displays the current absolute position data received from the motor's pulse coder. Encoder Tracking
: It acts as a live digital readout of where the axis stands in relation to its established zero point. Automatic Synchronization : When an axis is zeroed using Parameter 1815 (APZ)
, the system captures the value in 1860 to establish the reference coordinate system. Diagnostic Use
: Since users cannot manually change this value, it is primarily used by technicians to verify if an encoder is losing counts or to troubleshoot axis "droop" or slippage during emergency stops. Practical Implications in Machine Operation
The "work" performed by Parameter 1860 is essential for maintaining precision in several scenarios: Absolute vs. Incremental
: Machines using absolute encoders rely on this parameter to bypass the need for a physical "dog-type" home switch. The control reads 1860 at startup to instantly know where the tool is. Axis Droop Monitoring
: On vertical axes (like the Z-axis) without counterweights, the spindle may drop slightly when the servos lose power (e.g., during an E-stop) before the mechanical brake engages. Technicians use Parameter 1860 to measure this displacement precisely, ensuring it doesn't exceed the machine's safety limits. System Integrity
: Because it uses modular arithmetic (the value "wraps around" once it reaches its maximum limit), it continuously tracks movement over the full travel of the axis without losing its place. Important Safety Note:
Never attempt to force-write or manipulate parameters in the 1800-series (Axis-related parameters) without referring to the official Fanuc Parameter Manual
for your specific control model (e.g., 0i, 16i, 18i), as incorrect settings can cause machine collisions. CNC Training Centre to reset your machine's zero position using these encoder counts? FANUC? M6 toolchange position. | Practical Machinist
In FANUC CNC systems, Parameter 1860 specifically used to define the current absolute position of an axis when using an absolute pulse coder
. It is not typically referred to as a "work" parameter in a general sense, but rather a "reference position" or "absolute position" setting. Key Details of Parameter 1860 It stores the absolute position of each axis. Relationship with APC: APC (Absolute Position Coder)
bit in Parameter 1815 is set to 1, the system uses Parameter 1860 to track where the machine is, even after power is turned off.
You generally do not manually edit this parameter under normal "work" conditions. Instead, it is automatically updated by the CNC after a successful Reference Point Return or home position setting procedure. When You Might Use It fanuc parameter 1860 work
If you are seeing a "review" or discussion about "Parameter 1860 work," it likely refers to one of the following maintenance tasks: Setting Home Position:
After replacing an absolute encoder battery or a motor, you must "zero" the machine. Setting the APZ bit (in Parameter 1815) often triggers an update to the value stored in 1860. Synchronizing Positions:
If there is a mismatch between the physical position of the tool and what the screen shows, technicians may verify the value in 1860 to ensure the absolute pulse coder is communicating correctly. Troubleshooting Alarms: Alarms like APC Alarm 300
(Request for Reference Position Return) often involve verifying that the system is correctly writing data to Parameter 1860. MRO Electric Important Related Parameters Parameter 1815:
Used to enable absolute position detection (APC bit) and confirm that the zero point has been set (APZ bit). Parameter 1850: Sets the reference point offset. Parameter 1241:
Defines the coordinate value of the second reference point (often used for tool changes). MRO Electric Enable Parameter Write (PWE)
and back up your current settings before attempting to modify axis position data. Machine Metrics Are you currently facing a specific alarm code or trying to reset the home position on a machine? How to Enable Parameter Write Enable (PWE) on a Fanuc CNC
This is a full guide to Fanuc Parameter 1860, explaining what it does, why it matters, and how to set it correctly.
To truly understand how Parameter 1860 works, you need to look at three key areas:
Unlike static offsets, Parameter 1860 works dynamically: during a rigid tapping cycle, as the spindle reverses direction between hole bottom and retract, the CNC continuously applies the parameter 1860 adjustment to maintain synchronization. This ensures each thread is cut at the exact same helix angle, preventing "step" marks or oversized threads.
Formally, FANUC Parameter 1860 defines the number of pulses per revolution (feedback pulses) for the separate position coder mounted on a servo motor. In older or specific high-precision applications, particularly those involving α (Alpha) series servo motors, the motor often uses a separate pulse coder (distinct from the built-in sensor) to report its position back to the CNC. Parameter 1860 tells the control exactly how many electrical pulses this external coder generates during one complete turn of the motor shaft.
While many modern FANUC configurations rely on built-in serial encoders (managed by other parameters like 1820), Parameter 1860 remains essential for:
If you are setting up a new axis:
Disclaimer: This guide is for educational purposes. Always consult the specific Fanuc Parameter Manual for your specific control model (Series 16i/18i/21i/30i/31i/32i) and contact your machine tool builder's service department before modifying system parameters. Parameter 1860 (often referred to as ) is
Understanding Fanuc Parameter 1860: Reference Position and Absolute Encoders
Fanuc Parameter 1860 stores the absolute position of an axis within the current rotation of the encoder. It is a critical, read-only system parameter used by the CNC to track exactly where an axis is relative to its reference (home) position. If the value in Parameter 1860 is lost or incorrect—often due to a battery failure—the machine will lose its "sense" of where it is, leading to homing alarms. What is the Function of Parameter 1860?
In Fanuc CNC systems, Parameter 1860 acts as the machine's memory for axis position data when using absolute pulse coders (APC). Unlike incremental encoders, which must hit a "limit switch" or "dog" every time the machine starts up, absolute encoders always know their position.
Role in Homing: When an axis is successfully homed (set with Parameter 1815.4 APZ), the current encoder count is saved into Parameter 1860.
Data Type: It typically uses modular arithmetic, meaning the value "wraps around" based on the encoder's pulses per revolution.
Reference Completion: If the system detects a discrepancy between the physical position and the value in 1860, it may trigger a "Request for Reference Position Return". How Parameter 1860 Works During Startup
When you power on a Fanuc machine equipped with absolute encoders:
Verification: The CNC reads the current value from the encoder.
Comparison: It compares this value against the stored data in Parameter 1860.
Validation: If they match within a certain tolerance, the machine "remembers" its position immediately without requiring a manual zero return. Troubleshooting Common 1860 Issues
Most issues related to Parameter 1860 arise after a battery failure or motor replacement.
Alarms 300-349 (APC Alarms): These indicate that the absolute position data has been lost.
Reference Position Incomplete: If you reset Parameter 1815 but the machine doesn't move to the correct spot, the value in 1860 will often change automatically once a new reference point is established.
Soft Overtravel Alarms: If the stored position in 1860 suggests the machine is outside its travel limits upon startup, you may need to power on while holding "P" and "CAN" (Cancel) to bypass the check and re-home the axis. Step-by-Step: Setting the Reference Position The Technical Breakdown: How FANUC Parameter 1860 Works
Because Parameter 1860 is a system-generated value, you do not "type in" a value manually. Instead, you perform a procedure to let the CNC update it:
Master the Fanuc Zero Return Procedure in 5 Steps - CNCFixtech
FANUC Parameter 1860 is a critical axis-specific parameter used to store the absolute position data (machine coordinate) of an axis equipped with an absolute pulse coder (APC).
When a machine is equipped with absolute encoders, it does not need to be homed every time it is powered on because the CNC "remembers" the current position by reading the value stored in this parameter. Core Function and Mechanics
Data Storage: This parameter holds the current machine coordinate value for each axis. When you power off the machine, the encoder's battery keeps the internal pulse count active. Upon restart, the CNC compares the encoder's data with the value in Parameter 1860 to re-establish the absolute position without physical movement. Interaction with Parameter 1815:
Bit 5 (APC): If set to 1, the CNC knows the axis has an absolute encoder.
Bit 4 (APZ): This is the "Reference Position Established" flag. When this bit is 1, the CNC considers the value in Parameter 1860 to be valid and synchronized with the physical machine position. When Does It Change?
Automatic Updates: During normal operation, the CNC constantly updates this value as the axis moves.
Homing/Zero Return: When you perform a manual reference position return, the system sets the current physical position as the "zero" point and updates Parameter 1860 accordingly while flipping 1815#4 (APZ) to 1.
Loss of Position: If the encoder battery dies or the encoder is disconnected, the system loses the synchronization between the mechanical position and Parameter 1860. This triggers a 300 APC Alarm, requiring you to re-set the reference position. Setting or Resetting Procedure
If you lose your home position (e.g., after a battery failure), you must re-synchronize Parameter 1860. You can find detailed technical guidance in the official PARAMETER MANUAL. A typical reset involves: Enabling Parameter Write (PWE = 1).
Setting Parameter 1815 Bit 4 (APZ) to 0 for the specific axis.
Jogging the axis to the physical home position (often marked on the machine). Setting Parameter 1815 Bit 4 (APZ) back to 1.
Powering the machine off and back on to finalize the new position in Parameter 1860.
Important Safety Note: Because Parameter 1860 defines where the machine "thinks" it is, an incorrect value can cause soft overtravel alarms (e.g., Alarms 500 or 501) or, worse, a physical crash. Always verify your coordinates after modifying this parameter.
Are you currently dealing with a 300 APC Alarm on a specific axis? How to Enable Parameter Write Enable (PWE) on a Fanuc CNC