DeviceNet to EtherCAT Gateway Solves Multi-Slave Sync in Port Cranes
Project Background and Integration Challenges
A large modern container port embarked on a smart port initiative to integrate new automated rail-mounted gantry (RMG) cranes with existing rubber-tired gantry (RTG) cranes. The new RMG cranes use Beckhoff CX2040 PLCs as the main controller, leveraging EtherCAT for precise control of servo drives and sensors. The existing RTG cranes rely on Omron CJ2M PLCs with CJ1W-DRN32 modules acting as DeviceNet masters to manage field devices.
This setup created several critical issues:
- ● Protocol Barrier: EtherCAT and DeviceNet are incompatible at physical, data link, and application layers, preventing direct communication.
- ● Data Silos: Inability to exchange real-time job commands, equipment status, and position data led to inefficient scheduling and container transfer delays.
- ● Missing Safety Interlocks: No hardware-level safety interlocks between systems meant emergency stops and collision avoidance could not be coordinated, posing safety risks.
- ● High Maintenance Costs: Two separate control systems required diverse programming skills and a large inventory of spare parts.
- ● Limited Scalability: Future expansions were constrained by the existing network architecture.
The Solution: Protocol Conversion Gateway
A high-performance industrial gateway was deployed to bridge the two networks. This device acts as a DeviceNet to EtherCAT protocol converter, enabling transparent bidirectional data exchange. Key features include:
- ✓ Dual Slave Architecture: Functions as a slave on both the EtherCAT and DeviceNet networks, allowing seamless integration without disrupting existing masters.
- ✓ High-Speed Data Exchange: Supports up to 1440 bytes of input/output data with refresh cycles in the millisecond range, suitable for real-time control.
- ✓ Flexible Configuration: Web-based and dedicated tool configuration for easy parameter setup and online debugging.
- ✓ Robust Diagnostics: LED status indicators, network diagnostic parameters, and automatic reconnection upon link loss.
Implementation Steps
The integration followed a structured approach:
| Phase | Activities |
|---|---|
| Network Analysis | Analyzed existing DeviceNet topology and load; planned EtherCAT scan cycle and sync; defined data mapping tables. |
| Hardware Installation | Mounted gateway in control cabinet; connected EtherCAT to Beckhoff PLC and DeviceNet to existing network; set terminators. |
| Software Configuration | Imported ESI file into TwinCAT; configured EtherCAT slave parameters and PDO mapping; set DeviceNet slave in CX-Programmer; used web config for data mapping. |
| Data Mapping | Mapped DeviceNet inputs to EtherCAT outputs and vice versa; set byte order and conversion rules; configured watchdog and fault handling. |
| Testing & Optimization | Performed unit and integration tests; optimized communication cycle; ran 72-hour continuous test. |
Results and Benefits
The gateway successfully enabled real-time data exchange between the two crane systems, yielding significant improvements:
| Metric | Before | After |
|---|---|---|
| Data Exchange Latency | Manual, minutes | < 5 ms |
| Crane Coordination | Independent operation | Synchronized handshakes |
| Safety Interlocks | None | Cross-system emergency stop |
| Maintenance Complexity | Two separate skill sets | Unified diagnostics |
The solution preserved the existing investment in Omron PLCs and DeviceNet devices while enabling the advanced capabilities of EtherCAT-based control. It also provided a scalable foundation for future expansions.
Industry Applications
This protocol conversion approach is valuable in many sectors:
- ▶ Lithium Battery Manufacturing: Integrates coating, rolling, slitting, and die-cutting machines from different vendors using various industrial protocols, enabling real-time monitoring and quality traceability.
- ▶ Smart Logistics and Warehousing: Connects AGV dispatch systems with warehouse management and multi-brand conveyor controls for seamless material flow.
- ▶ Food & Beverage Packaging: Synchronizes fillers, labelers, and case packers in high-speed lines while ensuring FDA/GMP data traceability.
Conclusion
The successful deployment of a DeviceNet to EtherCAT gateway in a container port demonstrates the critical role of industrial protocol converters in modern automation. By enabling interoperability between legacy and new systems, such gateways protect capital investments, enhance safety, and pave the way for Industry 4.0 initiatives. As edge computing and 5G evolve, intelligent gateways will become even more central to industrial IoT architectures, offering advanced data processing and connectivity.
For engineers facing similar integration challenges, a dual-slave protocol gateway provides a cost-effective, reliable, and scalable solution that avoids the need for complete system overhauls.
