Troubleshooting Error E-4103: Axis Following Error on NXB-CTL-213-016 Motion Controller

Related Products

Tools Required

• Personal Protective Equipment (PPE)
• Lockout/Tagout (LOTO) kit
• Multimeter
• Metric hex key set
• Laptop with NexBot Configuration Suite software

Article

This article outlines the diagnostic and resolution procedure for the E-4103 Axis Following Error on systems utilizing the NexBot Robotics 213-016 8-Axis Motion Controller. This error indicates that the actual measured position of a robot axis has deviated from its commanded position by more than the configured tolerance. This safety feature halts robot motion to prevent damage to the equipment or workpiece.

Symptom

When this fault occurs, the robot will execute an emergency stop. The teach pendant or HMI will display the following message:

E-4103: Axis [X] Following Error

Where [X] is the number of the specific axis that has faulted (e.g., Axis 2, Axis 5). The system will require a fault reset and operator intervention before it can resume operation. The error may occur intermittently under high load or consistently upon any attempted movement of the affected axis.

Cause

The E-4103 error is triggered by a discrepancy between the controller's instructions and the physical feedback from the axis encoder. The most common causes include:

1. Mechanical Binding: A physical obstruction, damaged bearing, or lack of lubrication is preventing the axis from moving freely.
2. Encoder Malfunction: The axis encoder is providing incorrect or no position data due to internal failure, contamination, or slippage.
3. Loose or Damaged Cabling: The motor power cable or the encoder feedback cable has a loose connection, internal break, or shield degradation, causing signal loss.
4. Incorrect Servo Drive Parameters: The tuning parameters (e.g., gain, following error limit) for the servo drive are set too aggressively or too loosely for the application's dynamics.
5. Excessive Load: The robot is attempting to move a payload that exceeds its rated capacity, or the motion profile demands acceleration beyond the motor's torque capability.
6. Servo Motor or Drive Failure: The servo motor or its associated drive has an internal fault.

Resolution Steps

WARNING: Always follow proper Lockout/Tagout (LOTO) procedures before performing any inspection or maintenance inside the robot or controller cabinet. Ensure all stored energy is dissipated.

Step 1: Identify the Faulted Axis and Operating Conditions

Note the specific axis number indicated in the error message. Review the program and determine what the robot was doing when the fault occurred (e.g., high-speed travel, lifting a heavy part, complex coordinated motion).

Step 2: Perform a Visual and Physical Inspection

1. With the system powered down and locked out, carefully inspect the entire range of motion for the faulted axis. Look for any foreign objects, debris, or signs of collision that could cause a mechanical obstruction.
2. Manually move the axis through its range of motion (if brakes are released). It should move smoothly without excessive resistance, grinding, or catching. Any binding indicates a mechanical issue that must be resolved first.

Step 3: Inspect Electrical Connections and Cabling

1. Inspect the motor power and encoder cables for the affected axis. Check for cuts, abrasions, or tight bends that could damage the internal conductors.
2. Ensure the connectors at both the motor end and the controller/drive end are securely fastened. Unplug and re-seat the connectors to ensure a solid connection.
3. Pay close attention to the encoder cable, such as the NXB-CBL-512-011, as it is critical for position feedback. A loose connection here is a very common cause of this error.

Step 4: Verify Encoder Feedback

1. Power on the system and navigate to the I/O or Diagnostics screen on the teach pendant.
2. Find the raw position data for the faulted axis encoder (e.g., an encoder like the NXB-SNS-ENC521-013).
3. Under operator supervision and at very low speed (1-2%), jog the axis. The position counts should change smoothly and consistently. If the counts are erratic, jump to zero, or do not change, the encoder or its cable is likely faulty.

Step 5: Review Controller and Drive Parameters

1. Using the NexBot Configuration Suite software, connect to the NXB-CTL-213-016 controller.
2. Navigate to the axis configuration parameters for the faulted axis.
3. Verify that the 'Following Error Limit' parameter is set to the default value specified for your robot model (e.g., R-20, C-10). If this value has been set too low, the system may be overly sensitive to normal position deviations.
4. Check the servo gain and tuning parameters. If these have been recently modified, consider reverting them to a previously known good configuration.

Step 6: Isolate the Fault

If the problem persists and you have another identical axis on the robot, you can perform a component swap for diagnosis. This is an advanced step.

1. Swap the servo drives between the faulty axis and a known good axis. If the error moves to the good axis, the servo drive is the problem.
2. If the error remains on the original axis, the issue is likely the motor, encoder, or cabling.

Step 7: Contact Technical Support

If the steps above do not resolve the issue, contact NexBot Robotics Technical Support. Please have the following information ready:

• Robot model and serial number.
• Controller model: NXB-CTL-213-016.
• A description of the application and when the error occurs.
• Any alarm history or logs from the controller.

Prevention

• Perform regular scheduled maintenance, including checks for mechanical wear and proper lubrication.
• Periodically inspect all cabling for signs of wear and ensure proper strain relief is in place.
• Ensure all programs operate within the robot's specified payload and acceleration limits.
• Maintain regular backups of the controller configuration and parameters.

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