DeviceNet to EtherNet/IP Gateway for PLC-Robot Integration

The Integration Challenge on the Welding Line

In a car body welding station, the central controller was a Rockwell Allen-Bradley ControlLogix 5580 PLC, a powerful EtherNet/IP master responsible for coordinating the entire production line. The welding tasks were performed by a KUKA KR 16 robot, known for its precision and reliability. However, the robot communicated via DeviceNet, while the PLC used EtherNet/IP. Without a direct communication path, the line suffered from reduced efficiency and lack of real-time coordination.

This protocol mismatch is typical in brownfield automation projects where older fieldbus devices must be integrated into modern Ethernet-based architectures. The solution was a DeviceNet to EtherNet/IP gateway that acts as a bridge, translating data between the two networks seamlessly.

Key Equipment and Parameters

Understanding the technical specifications of each component is crucial for successful integration. The table below summarizes the main devices used in this application.

The gateway serves as the central translator. On the EtherNet/IP side, it appears as a standard I/O device to the PLC. On the DeviceNet side, it acts as the master, managing the robot and any other DeviceNet nodes. This architecture allows the PLC to exchange process data with the robot without any hardware modifications to either device.

Step-by-Step Configuration Guide

The integration process involves hardware setup, PLC programming, robot parameterization, and gateway configuration. Each step must be executed carefully to ensure reliable communication.

1. Physical Connections

First, connect the gateway’s EtherNet/IP port to the PLC’s network switch using a standard Ethernet cable. Then, connect the gateway’s DeviceNet port to the robot’s DeviceNet interface using a dedicated DeviceNet cable. Ensure proper termination resistors are installed at both ends of the DeviceNet trunk. Set the robot’s DeviceNet node address (MAC ID) using its teach pendant, for example, node 5. Avoid address conflicts with other devices on the same network.

2. PLC Configuration (EtherNet/IP Master)

Using Rockwell’s Studio 5000 software, create a new project for the ControlLogix 5580 controller. Add the gateway to the I/O configuration tree by importing its EDS (Electronic Data Sheet) file. This file provides the PLC with the gateway’s identity and communication parameters. After importing, configure the connection:

• Set the gateway’s IP address to match the PLC’s subnet.
• Define the input and output data sizes. For this application, 200 bytes input and 150 bytes output were sufficient to cover robot commands and status feedback.
• Verify the connection by pinging the gateway from the PLC’s network interface.

3. Robot Configuration (DeviceNet Slave)

On the KUKA KR 16 teach pendant, navigate to the DeviceNet settings. Set the baud rate to match the gateway’s setting (e.g., 250 kbps for a balance of speed and distance). Confirm the node address (e.g., 5). The robot’s I/O mapping must align with the data sizes defined in the PLC and gateway. Typically, the robot expects certain bytes for control commands and provides status bytes.

4. Gateway Configuration

Using the gateway’s proprietary configuration tool, create a new project and select the TX 131-RE-DNM/EIS model. Configure the EtherNet/IP side:

• IP address, subnet mask, and default gateway consistent with the PLC network.
• Input/output assembly sizes matching the PLC settings (200/150 bytes).

On the DeviceNet side, set the master’s node address (e.g., 1) and the baud rate (250 kbps). Add the robot as a slave device with its node address and configure the I/O data mapping. Download the configuration to the gateway. After a power cycle, the gateway should establish communication with both networks.

Data Exchange and Operational Benefits

Once configured, the PLC can send welding instructions to the robot in real time. Typical data includes:

• Welding trajectory points (X, Y, Z coordinates and orientation).
• Welding parameters: current, voltage, travel speed.
• Start/stop commands and program selection.

The robot continuously feeds back status information:

• Welding complete signal.
• Fault codes and alarms.
• Actual position and process data for quality monitoring.

This bidirectional communication enables synchronized operation, reduces cycle time, and improves weld quality. The gateway’s diagnostic LEDs and web interface simplify troubleshooting. The solution is scalable: additional DeviceNet devices (e.g., grippers, sensors) can be added to the same gateway, maximizing the investment.

Best Practices for Protocol Conversion Projects

Based on this case study, here are some recommendations for similar integrations:

• Network Planning: Ensure proper IP addressing and DeviceNet node assignments. Document all settings.
• Data Mapping: Carefully define the I/O data structure. Use consistent byte ordering and data types between the PLC and robot.
• Testing: Simulate communication before deploying to production. Use the gateway’s monitoring tools to verify data exchange.
• Training: Train maintenance personnel on the gateway’s diagnostic features to reduce downtime.

As Industry 4.0 initiatives drive the adoption of EtherNet/IP and other industrial Ethernet protocols, gateways will continue to play a vital role in bridging the gap between old and new equipment. This automotive welding example demonstrates that with the right gateway and careful configuration, seamless communication is achievable, leading to improved productivity and quality.