PROFINET to DeviceNet Gateway for Steel Mill Communication
In modern steel rolling mills, integrating legacy devices with new control systems often presents a significant challenge. A common scenario involves connecting a DeviceNet-based LED display to a Siemens S7-1500 PLC running PROFINET. This is where a PROFINET to DeviceNet gateway becomes an essential tool, acting as a bridge between two incompatible industrial networks.
This article explores a real-world application where such a gateway was deployed to display critical production data—date, steel grade, laying head status, and temperature—on a large LED screen in a rolling mill. The solution not only solved the protocol mismatch but also simplified engineering, improved stability, and reduced costs.
Understanding the Communication Challenge
The control system in the rolling mill was built around a Siemens S7-1500 PLC, which uses PROFINET—a high-speed Industrial Ethernet protocol. The LED display controller, however, only supported DeviceNet, a CAN-based fieldbus. Without a gateway, these two devices could not exchange data directly.
The gateway was configured as a PROFINET slave on the PLC side and as a DeviceNet slave on the display side. This dual role allowed it to translate data between the networks seamlessly. The PLC sent data to the gateway over PROFINET, and the gateway repackaged it into DeviceNet messages for the LED controller.
Key Functions of the Gateway
The gateway performed several critical functions beyond simple physical connectivity:
- Protocol Conversion: It handled the complete transformation between PROFINET and DeviceNet, including data framing, addressing, and timing.
- Data Mapping: Engineers mapped PLC data blocks directly to DeviceNet I/O assemblies using the gateway’s web-based configuration tool. This included strings (date, steel grade), booleans (machine status), and floats (temperature).
- Electrical Isolation: The gateway provided galvanic isolation between the two networks, protecting the PROFINET side from faults on the DeviceNet bus.
- Buffering: It buffered data to handle temporary communication interruptions without affecting the PLC scan cycle.
Implementation Steps
The gateway used in this project featured a web interface for configuration, which streamlined the setup process:
- Configured the PROFINET device name and IP address, and imported the GSDML file generated by TIA Portal.
- Set the DeviceNet baud rate (125 kbps) and MAC ID to match the LED controller.
- Mapped the PLC data block addresses to the corresponding DeviceNet data areas using a simple drag-and-drop interface.
No complex programming was required on the LED controller side, significantly reducing engineering time.
Benefits of Using a Protocol Gateway
| Benefit | Description |
|---|---|
| Simplified PLC Programming | PLC engineers only need to write data to a dedicated data block; no DeviceNet protocol knowledge is required. |
| Enhanced System Stability | Electrical isolation and data buffering prevent DeviceNet faults from impacting the PROFINET network. |
| Cost Savings | Existing DeviceNet LED displays can be reused, avoiding the expense of new PROFINET-compatible hardware. |
| Real-Time Performance | Gateway processing delay is in the millisecond range, ensuring timely display updates for operators. |
Technical Considerations for Gateway Selection
When choosing a PROFINET to DeviceNet gateway for industrial applications, consider the following parameters:
- Data throughput: Ensure the gateway can handle the required I/O data size (typically up to 512 bytes per direction).
- Configuration ease: Web-based or software tools with GSDML support simplify integration.
- Environmental ratings: For steel mills, look for extended temperature ranges and vibration resistance.
- Diagnostic capabilities: LEDs and web diagnostics help troubleshoot network issues quickly.
Conclusion
The PROFINET to DeviceNet gateway proved to be a reliable and cost-effective solution for integrating legacy LED displays into a modern Siemens S7-1500 control system. By handling protocol conversion, data mapping, and isolation, it enabled seamless communication without disrupting existing operations. For any industrial facility facing similar protocol challenges, a gateway offers a practical path to unified automation.
