Fanuc 7115 Alarm

Navigate to SYSTEM → PMC → DIAG → STATUS. Look for diagnostic address DGN 300 or 400 (model dependent). These bits will tell you where the I/O link failed.

The solenoid valve that releases the brake/clamp might be stuck or sluggish. The CNC tells the valve to open, but the mechanical spool inside doesn't move fast enough, or the feedback sensor (limit switch) on the clamp cylinder is dirty or broken.

If an operator or technician has forced a diagnostic bit (e.g., G54.0) using the PMC Maintenance screen and then saves the ladder while that force is active, the system may reboot with a logical inconsistency. The 7115 alarm appears because a forced coil exists in a state that violates the ladder’s normal logic flow.

Alarm Code: 7115 Alarm Message: OVERSPeed (or related parameter error) Applicable Systems: Fanuc Series 16i/18i/21i, 16/18/21, 0i, and 30i Series controls.

Alarm 7115 is a critical safety alarm indicating that the system has detected a condition where the spindle or servo motor speed has exceeded the maximum allowable limit defined in the control parameters. Alternatively, it may indicate that the control has calculated an invalid speed based on current parameter settings.

When this alarm occurs, the machine will typically initiate an emergency stop to prevent mechanical damage to the motor, spindle bearings, or drivetrain components.

If the hardware checks out, the ladder is likely corrupted.

Press the "MSG" (Message) key. Note the sub-codes or data displayed alongside the 7115.

| Alarm | Relationship | | :--- | :--- | | 7100 | Over travel alarm | | 7106 | Reference point return deceleration signal error | | 7107 | Reference point return dog signal not detected | | 7110 | Reference point return speed error | fanuc 7115 alarm

Conclusion: The FANUC 7115 alarm is a configuration or position-related error preventing safe reference point return. It is usually resolved by correcting parameter 1006#5 or moving the axis away from the deceleration dog. Setting 3004#5 = 1 is a common and safe permanent solution for most machines.

The FANUC Alarm 7115 is an EtherNet/IP Error typically indicating a communication failure or configuration mismatch between the FANUC robot (acting as either a Scanner or Adapter) and a remote device. Direct Meaning

This alarm signifies that an EtherNet/IP connection has been lost or cannot be established. It is often accompanied by a sub-code (e.g., 7115, 1) that provides more specific detail about which connection point is failing. Common Causes

Physical Layer Issues: A damaged Ethernet cable, loose connector, or a faulty network switch.

Configuration Mismatch: The Input/Output (I/O) sizes defined in the robot's EtherNet/IP setup do not match the sizes defined in the PLC (e.g., Allen-Bradley Logix controller).

IP Address Conflicts: Another device on the network is using the same IP address as the robot or the target device.

Timeout: The "Requested Packet Interval" (RPI) is set too low for the network traffic, causing the connection to drop. Troubleshooting Steps

Check Hardware: Inspect the Ethernet cable plugged into the robot's CD38A or CD38B port. Ensure the link lights on the port and the network switch are active. Verify I/O Sizes: Navigate to SYSTEM → PMC → DIAG → STATUS

On the Teach Pendant, go to [ MENU ] → I/O → EtherNet/IP.

Compare the Input Size (words) and Output Size (words) with your PLC configuration. They must match exactly.

Ping the Device: Use the robot's "Ping" utility ([ MENU ] → Setup → Host Comm) to see if the robot can see the PLC/remote device on the network.

Cycle Power: If configuration changes were made, a Cold Start (turning the controller off and back on) is often required for the EtherNet/IP settings to take effect.

Check Connection Status: In the EtherNet/IP setup screen, check if the connection is "Offline," "Error," or "Running" to narrow down which specific slot is failing.

Do you have a specific sub-code appearing with the 7115 alarm, or are you currently unable to ping the robot?

The Fanuc alarm is most commonly associated with the Spindle Switch Control feature on machines like Mori Seiki. What is the 7115 Alarm? Spindle Switch Control Alarm

(SPN 1), which indicates that a required control condition for spindle operation has not been met. It often triggers when the CNC is attempting to switch spindle modes (such as high/low gear or speed ranges) and fails to confirm the state of the hardware. Common Causes & Troubleshooting Contactor Issues: Alarm Code: 7115 Alarm Message: OVERSPeed (or related

The spindle speed switching contactors are not pulling in correctly during power-on or mode switching. 24VDC Power Supply Failure:

A frequent culprit is a failed or weak 24VDC power supply (often Izumi brand in Mori Seiki cabinets), which prevents the relays and contactors from activating. Interlock or Panel Issues: It often appears alongside an EX0099 Panel Alarm

, which can point to a broader power issue in the operator panel or control circuit. Feedback Timeout:

The system timed out while waiting for a confirmation signal (proximity switch or auxiliary contact) that the spindle has successfully switched states. Recommended Steps Check 24V DC Supplies:

Measure the output of the 24V power supplies in the electrical cabinet. Even if they show 24V with a multimeter, they may be failing under load. Inspect Spindle Contactors:

Manually check if the high/low range contactors are physically sticking or if their coils are burned out. Verify Proximity Switches:

Ensure that the sensors detecting the gear or spindle range position are clean and functioning. Is this happening during a gear change or right when you the machine?

Follow this sequence to diagnose the 7115 alarm:

| Step | Action | | :--- | :--- | | 1 | Power off and on the CNC. Sometimes the alarm occurs due to a transient state. | | 2 | Manually jog the axis to the middle of its travel range, away from the decel dog. Then attempt reference return again. | | 3 | Check the deceleration dog (limit switch or proximity sensor). Ensure it is not stuck in the active (depressed) state when the axis is away from it. | | 4 | Monitor the decel dog signal on the PMC diagnostic screen: Typically X address (e.g., X9.0 for Z-axis). The signal should be 1 when the dog is not activated, and 0 when the axis is on the dog. If reversed, invert the signal logic in PMC or check wiring. | | 5 | Check Parameter 3004#5 (RCD) – Set to 1 to disable the direction check (temporary workaround only for testing). If alarm disappears, the root cause is a configuration or hardware direction issue. | | 6 | Check Parameter 1006#5 for the axis. If 0: reference return in + direction. If 1: reference return in – direction. Confirm this matches the physical decel dog placement and machine design. |