The challenge: Cycle times in the production environment

In battery production, every second counts. Control units must be programmed during the production process without interrupting the flow. Traditionally, flashing is done via CAN or CAN FD. These buses are widely used in the automotive industry but offer limited bandwidth. Previous approaches involved pre-processing the flash data on the PC and then transmitting it as individual CAN messages. This resulted in higher latencies and therefore unnecessary delays. For system integrators and suppliers, this poses a significant risk: exceeding the required cycle time can lead to costly process adjustments. OEMs, in turn, demand reliable solutions that integrate seamlessly into existing test environments and are future-proof. One solution that has proven successful in practice are DoIP gateways.

Image 1: Structure of the DoIP message frame format

What is Diagnostics over IP (DoIP)?

DoIP is standardized in ISO 13400 and defines how diagnostic data is transmitted over Ethernet networks. Unlike classic CAN-based communication, DoIP relies on the TCP/IP protocol, which is well-established in the IT world and enables high data rates with low latency. By using Ethernet as the physical layer, bandwidths ranging from 100 Mbit/s to 1 Gbit/s can be achieved – magnitudes that represent a quantum leap compared to classic CAN and CAN-FD buses (1 to 8 Mbit/s).

DoIP also offers standardized mechanisms for addressing and identifying electronic control units (ECUs). This allows multiple ECUs to be addressed in parallel, which is crucial for the flashing process in complex battery systems with numerous submodules. Furthermore, DoIP continues to support the familiar UDS services (Unified Diagnostic Services, ISO 14229)  without modification. This means that existing diagnostic and flashing tools can continue to be used without requiring any adjustments to the application logic.
From a technical perspective, DoIP is based on layers 2 to 4 of the OSI model: Ethernet as the physical layer, IP for addressing, and TCP or UDP for transport. This ensures that DoIP adheres closely to established IT standards and enables easy integration into modern vehicle networks.

Image 2

The role of ISO-TP

ISO-TP (ISO 15765-2, "Transport Protocol") for CAN and CAN FD splits large firmware files into smaller frames, assigns them numbers and acknowledgments, and reassembles them correctly at the receiver. This enables the reliable flashing of files several hundred megabytes in size. In a DoIP gateway, the gateway then ensures that the timing and sequence are maintained on the CAN bus.
Another advantage of DoIP in combination with ISO-TP is the ability to integrate security mechanisms such as Transport Layer Security (TLS). This not only accelerates flashing and diagnostic processes but also protects them against unauthorized access – an aspect that is becoming increasingly important, especially for remote updates and in networked vehicle architectures.

The DoIP gateway as a bridge between worlds

Many electronic control units (ECUs) lack their own Ethernet interface, so a DoIP gateway as an intermediary between the two communication environments is requires. It receives DoIP packets from the diagnostic tester, converts them into CAN or CAN FD messages, and forwards the ECU's responses back to the Ethernet network. This allows even ECUs that are not Ethernet-enabled to be integrated into modern diagnostic and flashing environments.

Image 3: The DoIP gateway as a bridge between worlds

An example of a high-performance DoIP gateway is the CANnector Automotive Gateway from the HMS product brand Ixxat, which operates in standalone mode and supports both DoIP and ISO-TP. Together with the CANeasy test software, into which ODX and PDX flash containers can be directly imported, this results in a powerful solution for efficient flashing processes. The practical benefit is particularly evident in the significant reduction of flashing times: In a recent application, a time saving of approximately 20 percent was achieved. This is possible because data processing no longer takes place on the PC, but directly in the gateway, thus minimizing latency. Using the Advanced Configuration Tool (ACT), the gateway can be configured very easily, and existing ARXML files can be integrated without difficulty. In addition to the actual flashing function, diagnostic tasks, logging, or residual bus simulation can be performed in parallel without interrupting the process. For OEMs, this means adhering to strict cycle time specifications, while suppliers benefit from an easy-to-implement and scalable solution that also takes into account future requirements for larger software packages and more complex diagnostic data.

Conclusion

Firmware flashing of battery ECUs remains a key task in electromobility. While classic CAN-based methods are reaching their limits, DoIP gateways offer an efficient and future-proof solution. They bridge the gap between traditional bus systems and modern Ethernet-based protocols – ensuring that production lines can reliably meet their cycle times.
The relevance of DoIP is also evident in new standards such as SAE J1979-3, which specify diagnostic functions for electric vehicles via DoIP. This makes Software-Defined Vehicles (SDVs) a reality, where software updates and diagnostics must be performed in increasingly shorter cycles. Real-world examples demonstrate that DoIP already offers not only speed but also flexibility for the vehicle diagnostics of tomorrow.