Intermittent EtherCAT communication loss on R-50 robot arm

Description

We are experiencing intermittent communication dropouts on one of our R-50 robots on the main assembly line. The robot will suddenly stop mid-cycle, and the controller flashes an EtherCAT communication error. This happens 3-4 times per shift, causing significant downtime. We are using the NexBot Drives NET522-006 Fieldbus Cable to connect the robot's drive stack to the main system controller. The cable is routed through a high-flex energy chain. We have tried power cycling the entire cell and have visually inspected and reseated the connectors at both the controller and the robot base, but the problem persists. The issue seems to occur most frequently when the arm is performing rapid, complex movements, leading us to suspect the cable itself may be failing internally from fatigue after two years in service.

Symptoms

• Robot halts unexpectedly during operation
• Controller displays 'EtherCAT Slave Communication Timeout'
• Loss of connection is more frequent during high-speed, multi-axis movements
• System requires a full restart to re-establish communication

Resolution

The support team analyzed the symptoms and concluded that the intermittent nature of the fault, especially during dynamic movements, was characteristic of internal conductor fatigue in the high-flex cable. After millions of cycles, micro-fractures can develop in the copper conductors, leading to transient connection loss that is difficult to diagnose with a simple continuity test on a static cable. The resolution was to replace the existing fieldbus cable with a new unit and to verify the installation follows best practices for bend radius and strain relief to maximize the service life of the replacement.

Resolution Steps

1. Perform a full LOTO (Lockout/Tagout) procedure on the robotic cell.
2. Disconnect the suspect NXB-CBL-NET522-006 Fieldbus Cable from the controller's EtherCAT master port and the robot's base connection panel.
3. Carefully remove the old cable from the energy chain, documenting its path.
4. Install a new NXB-CBL-NET522-006 cable, ensuring the routing respects the specified minimum bend radius and that strain relief clamps are properly secured at both ends.
5. Reconnect the new cable to the controller and robot.
6. Remove the LOTO and power up the system.
7. Clear the E-4502 fault from the controller log.
8. Run the robot through a comprehensive diagnostic routine, including full-range movements, for 60 minutes to confirm the connection is stable.