Fanuc Parameter 1860 [work] Page

FANUC Parameter 1860: The Definitive Guide to Reference Position Return Speed

Troubleshooting Scenarios

C. Parameter 1860 on Rotary Axes

For rotary tables (4th/5th axes), set 1860 in degrees per minute. A typical range: 1000–3000 deg/min. Because rotary inertia is lower than linear axes (usually), higher 1860 is acceptable, but watch for mechanical lash.

10. Conclusion

Parameter 1860 is far more than a simple number in a FANUC parameter list. It is a precision tuning tool that balances cycle time against positional repeatability. Too high, and you risk inconsistent homing and alarms. Too low, and you waste seconds on every startup—seconds that add up to hours of lost productivity over a machine's lifetime.

For the CNC engineer, mastering Parameter 1860 means understanding not just the parameter itself, but the entire homing sequence: the rapid approach, the deceleration dog, the marker pulse detection, and the final grid position. When optimized, 1860 delivers a fast, rock-solid reference return that ensures every part starts from the exact same zero point.

Final Recommendation: On any new or unfamiliar FANUC-controlled machine, verify Parameter 1860 as part of your maintenance checklist. Test repeatability annually. A few minutes spent tuning 1860 will pay dividends in consistency and throughput for years to come.

This article applies to FANUC Series 0i, 16i, 18i, 21i, 30i, 31i, 32i, and Power Motion i controls. For specific machine tool builder variations, consult your original machine documentation.

Understanding Fanuc Parameter 1860: The Key to Absolute Position Data

Fanuc Parameter 1860 is a critical axis-specific setting used across various Fanuc CNC control series, including the 16, 18, 21, and 0i models. It is primarily responsible for storing and managing the current absolute position data when an absolute position detector (absolute encoder) is used. What is Fanuc Parameter 1860?

In Fanuc systems equipped with absolute encoders, the control must maintain a constant "knowledge" of where each axis is located, even after the power is cycled. While Parameter 1815 defines the status of the detector (such as whether it is enabled or if the home position is set), Parameter 1860 actually holds the numerical position data that corresponds to the mechanical position of the machine. Function: Stores the absolute position data for each axis.

Relationship to Hardware: It works in tandem with the absolute pulse coder (APC) on the motor to ensure the machine coordinate system matches the physical location of the table or tool.

Auto-Update: Under normal operation, you do not manually edit this parameter; the CNC system updates it automatically as the machine moves. Parameter 1860 vs. Parameter 1815

It is common for technicians to confuse these two, as they both relate to the absolute positioning system. Parameter 1815 Parameter 1860 Purpose Configuration and Status Bits Actual Position Data Common Bits APC (Absolute Pulse Coder), APZ (Absolute Position Zero) Numerical coordinate value Manual Action Often toggled (0 to 1) during home position resets Rarely edited manually; usually reset by a "Zero Return" When Should You Check Parameter 1860?

You will typically only interact with Parameter 1860 during major maintenance or troubleshooting of the home position. PARAMETER MANUAL

In FANUC CNC systems, Parameter 1860 a critical coordinate-related parameter used to store the current position of an axis when using an absolute pulse coder (APC)

. It essentially serves as the CNC's internal memory for where the machine tool is located in space even after the power is turned off. Core Function and Purpose Position Retention:

Unlike incremental encoders that require a homing sequence (zero return) every time the machine is powered up, an absolute encoder remembers its position. Parameter 1860 holds this numerical value for each controlled axis. System Correspondence:

It maintains the mathematical relationship between the mechanical position of the machine and the electronic pulses sent by the encoder. Relation to Parameter 1815 Parameter 1860 works in tandem with Parameter 1815 , which manages the absolute encoder's status: en.industryarena.com APC (1815 bit 5): Indicates if an absolute position coder is being used. APZ (1815 bit 4):

This bit tells the system if the reference position (zero point) has been established. When you set the home position manually, the system updates Parameter 1860 with the current coordinate and then automatically flips the APZ bit to "1" to confirm the zero point is set. en.industryarena.com When to Modify or Check Parameter 1860 Losing Home Position:

If the backup battery for the absolute encoder fails, the system loses the data in Parameter 1860, resulting in a "300 APC Alarm: Need ZRN" (Zero Return Needed). Motor or Encoder Replacement:

When a motor or encoder is swapped, the physical link to the previous "zero" is broken. You must reset the reference position, which clears and updates the value in Parameter 1860. Mechanical Realignment:

If the machine's physical home position needs to be shifted (e.g., after a crash or maintenance), technicians may manually adjust the value in 1860 or perform a new zero-set sequence to overwrite it. en.industryarena.com Safety Warning

Modifying coordinate parameters like 1860 can cause the machine to "think" it is in a different location than it physically is. Incorrect settings can lead to machine crashes overshooting stroke limits . Always back up your parameters before making changes. Fryer Machine Systems Are you currently troubleshooting a "300 APC Alarm" or looking for the specific manual steps to reset your home position? Fanuc > Resetting Reference Position For Absolute Encoder

1. Navigate to the parameter lock. Change it from a zero to a one. 3. Press the SYSTEM hard key and navigate to parameter 1815 en.industryarena.com

The CNC router, a five-axis beast named “Goliath,” had fallen silent. Not the good silence of a job well done, but the terrible silence of a catastrophic alarm.

#417 SERVO ALARM: DIGITAL SERVO PARAMETER UNMATCHED

The night shift supervisor, a man named Cole who had twenty years of sawdust in his blood, stared at the red text on the amber screen. The machine was dead. A three-hundred-thousand-dollar paperweight. And a rush order of aerospace ribs was due at 6:00 AM. fanuc parameter 1860

“It’s the 1860,” whispered Margie, the ancient programming wizard who had been lured out of retirement six times.

Cole rubbed his stubble. “The what?”

Margie pulled a dusty, coffee-stained maintenance manual from a drawer. She flipped to a page that looked like a circuit diagram for a nuclear reactor. “Parameter 1860. The reference counter for the C-axis. It tells the servo motor where ‘home’ is—not just a physical switch, but the exact, magical alignment of the motor’s internal magnetic poles with the ballscrew.”

“So fix it,” Cole grunted.

“It’s not a number you type,” she said, her voice low. “It’s a relationship. It’s the handshake between the motor’s rotor and the amplifier’s brain. If it’s wrong, the motor will scream, or just… refuse to exist.”

The cause was a mystery. A power blip? A failing battery in the servo amp? A gremlin? All Cole knew was that Goliath was catatonic.

Margie grabbed a tool no one used anymore: a FANUC servo guide box, a clunky grey brick with a single rotary switch and a two-line LCD. She disconnected the main power, pulled the heavy motor cable from the C-axis drive, and clipped the guide box in its place.

“We’re going to talk to the motor directly,” she said. “Bypass the controller. Ask it where its soul is.”

For ten minutes, she turned the rotary switch through a sequence of diagnostic modes: F-DAT, A-DAT, C-DAT. The LCD flashed cryptic hex codes. Finally, she found it: a blinking value, 1860. The current value was +127.

She pulled out her phone, opened a secret FANUC field engineer PDF (watermarked “CONFIDENTIAL – NOT FOR CUSTOMER”), and cross-referenced the motor model number: A06B-0243-B100.

The correct 1860 value for that motor, at that specific alignment, was -211.

“See?” she said, pointing. “The battery backup glitched. The amplifier forgot the offset. It thinks the rotor is 338 electrical degrees away from where it actually is. The servo is trying to correct a ghost.”

Cole didn’t understand degrees or rotors. He understood time. “Can you fix it?”

“I have to teach it.”

She powered the main breaker back on. The cabinet fans whirred. The red alarm still blazed on the main screen. But on the guide box, she went into Parameter Tuning Mode.

She didn’t type -211.

Instead, she rotated the C-axis motor shaft by hand—a tiny, precise, agonizing turn. She used a torque wrench set to 2.5 newton-meters, and a dial indicator on the tool holder. The needle moved 0.002 inches. She stopped.

Then, on the guide box, she pressed SET and INC simultaneously for three seconds.

The guide box beeped. The main CNC screen flickered. The red #417 alarm turned yellow, then green, then vanished.

The LCD on the guide box now read:

P1860 = -211 (FIXED)

She reconnected the motor cable, closed the cabinet, and looked at Cole. “Type G28 C0. Let’s see if it bites.”

Cole’s finger trembled over the CYCLE START button. He pressed.

For one terrible second, nothing happened. Then, with a familiar, powerful hum, the C-axis rotated smoothly to its home position and locked with a solid clunk. The tool changer cycled. The spindle warmed up. FANUC Parameter 1860: The Definitive Guide to Reference

Goliath was alive.

“Never forget,” Margie said, closing the manual. “Behind every fancy CAD/CAM model and every five-axis toolpath, there’s a single, lonely parameter. 1860. It’s the spine. Break it, and the whole body falls.”

Cole nodded, reset the feed rate to 100%, and loaded the first block of code. The chips began to fly. The rush order would be just two hours late—a miracle.

From that night on, Cole kept a laminated card taped inside the cabinet door. On it, in permanent marker, was written:

“If all else fails, check 1860. It’s not a bug. It’s a broken promise between the motor and the world.”

It was a late Tuesday shift at the machine shop when the lights flickered and the old Fanuc-controlled mill went dark. When the power finally hummed back to life, the operator didn't see the usual ready screen. Instead, a series of APC (Absolute Pulse Coder) alarms blinked in angry red—the backup batteries had finally given up, and the machine had "forgotten" where it was.

The lead technician, Sarah, knew this was a high-stakes moment. In the world of Fanuc CNCs, losing your reference point isn't just a minor glitch; it’s like a pilot waking up mid-flight with no idea where the horizon is. The Hidden Tracker: Parameter 1860

Sarah dove into the system menus, bypassing the standard position screens. She was looking for Parameter 1860.

In Fanuc technical lore, Parameter 1860 is often seen as a "ghost" value. It represents the current position of the absolute encoder—a raw, digital count that tracks every rotation of the motor even when the power is off. While operators usually focus on Parameter 1815 (which actually sets the home bit), 1860 is the underlying data that makes that home bit meaningful. The Re-Homing Ritual

Sarah began the delicate process of "teaching" the machine its home again:

Setting the Stage: She switched to MDI mode and enabled Parameter Write Enable (PWE).

Clearing the Error: She navigated to Parameter 1815 and toggled the APZ (Absolute Position Zero) bit to 0.

The Manual Move: Using the handwheel, she moved the Z-axis to its physical home position, watching the raw encoder values in the background—data that would eventually populate 1860.

The Lock-In: She flipped the APZ bit back to 1. The machine took a "snapshot" of its current state, linking the physical position to its internal digital map. The Lesson Learned

As the machine homed successfully and the alarms vanished, Sarah reminded the crew: "Parameter 1860 isn't something you change; it's something the machine remembers for you.". If that battery dies, that memory vanishes, and you're back to manual alignment and clocking holes just to get the spindle moving again.

The mill hummed back to life, its digital "brain" finally in sync with its steel limbs, ready for the next part.

Are you currently troubleshooting a battery failure or trying to re-home an axis on a Fanuc machine? FANUC? M6 toolchange position. | Practical Machinist

A very specific topic!

Understanding FANUC Parameter 1860

FANUC is a well-known Japanese company that specializes in the development and manufacture of CNC (Computer Numerical Control) systems, robots, and other industrial automation products. In the context of FANUC CNC systems, parameters are used to configure and customize the behavior of the machine.

What is Parameter 1860?

Parameter 1860 is a specific setting in FANUC CNC systems that relates to the "Input/Output" or "I/O" configuration.

Description:

Parameter 1860 is used to specify the type of I/O device connected to the CNC system. This parameter allows you to configure the CNC system to communicate with various I/O devices, such as programmable logic controllers (PLCs), input/output units, or other CNC systems. This article applies to FANUC Series 0i, 16i,

Setting Values:

The setting values for Parameter 1860 vary depending on the specific FANUC CNC system and the I/O device being used. Here are some common setting values:

0: No I/O device (or Disabled)
1: FANUC I/O unit (e.g., I/O LINK or I/O Unit-M)
2: **PLC (e.g., SIEMENS, MITSUBISHI, or OMRON)
3: DeviceNet (a fieldbus protocol)
4: Profibus (a fieldbus protocol)
5: CANopen (a fieldbus protocol)

How to Set Parameter 1860:

To set Parameter 1860, follow these general steps:

Enter the CNC system's parameter setting mode.
Locate Parameter 1860 in the parameter list.
Set the desired value using the CNC system's keypad or pendant.
Press the "Set" or "Enter" key to save the new value.

Important Considerations:

When setting Parameter 1860, ensure that:

You have the correct documentation for your specific FANUC CNC system and I/O device.
You understand the I/O device's configuration and communication requirements.
You set the correct value to avoid any potential communication errors or system malfunction.

Troubleshooting:

If you encounter issues with Parameter 1860 or I/O communication, check:

The I/O device's connection and configuration.
The CNC system's I/O configuration and Parameter 1860 setting.
The system's error messages or alarm codes for clues.

By understanding and correctly setting Parameter 1860, you can ensure proper I/O communication between your FANUC CNC system and external devices, enabling efficient and reliable machine operation.

Fanuc parameter 1860 specifies the current position of an absolute position detector (absolute pulse coder) in machine coordinates.

It is an axis-specific parameter used by the CNC to track the physical location of each axis even when power is removed, provided the backup battery is functional. 🛠️ Key Functionality

Absolute Position Tracking: Stores the current machine coordinate value for each axis using an absolute pulse coder.

Automatic Updates: Under normal operation, the CNC updates this value automatically as the axis moves.

Recovery Use: Primarily referenced during "Home Position" (Reference Return) recovery after battery failure or motor/encoder replacement. ⚙️ Usage and Configuration

Parameter 1860 is closely linked with parameter 1815 (APC and APZ bits), which determines if an axis uses an absolute detector and if the zero position is established. Data Type: 2-word (long integer) axis parameter.

Initial Setup: When replacing a detector or battery, you often manually move the axis to the desired "Zero" and then toggle bits in parameter 1815 to force 1860 to synchronize with that mechanical position.

Diagnostics: If 1860 does not match the actual physical position, it typically triggers a 300-series SV Alarm (e.g., SV300 APC Alarm: Needs Ref Return). ⚠️ Warning

Incorrectly modifying parameter 1860 or its associated homing parameters (like 1815 or 1850) can cause the machine to move unpredictably or crash into physical hard stops. Always enable Parameter Write Enable (PWE) on the Setting Screen before attempting changes.

If you tell me the specific alarm code you're seeing or if you just replaced a battery, I can give you the exact step-by-step procedure to reset your home position. Series 16i/18i/21i/20i-A Maintenance Manual, GFZ-63005EN/02

1. What is Parameter 1860? (Fundamental Concept)

Parameter 1860 (often displayed as PRM 1860) defines the decelerated feedrate that an axis uses after it detects the reference return deceleration dog (limit switch) during a manual or automatic reference position return (G28).

Step 4 — Find Maximum Stable Value

The maximum stable 1860 is the highest speed at which the axis stops within 1-2 encoder counts every time. Back off by 10-15% for margin.

How to Adjust Parameter 1860

⚠️ WARNING: Always back up your machine parameters to a memory card or USB stick before making any changes. Incorrect parameter settings can cause the machine to behave unpredictably.

The Two-Speed Reference Return Process

To understand 1860, you must first understand the two-phase homing sequence on a FANUC control:

| Phase | Speed Control | Parameter | Description | |-------|---------------|-----------|-------------| | 1. High-Speed Approach | Rapid traverse (G00) | 1420, 1421, 1422, 1423 | Axis moves toward the deceleration dog at rapid speed. | | 2. Low-Speed Search | Parameter 1860 | PRM 1860 | After hitting the dog, axis decelerates to this speed to find the 1-grid signal (encoder marker pulse). | | 3. Final Stop | N/A (control logic) | N/A | Axis stops at exact reference position (grid point). |

Key Insight: Parameter 1860 sets the creep speed—a slow, precise velocity that allows the CNC to detect the exact rising edge of the position coder's one-revolution signal without overshoot.