Remote-controlled edge protocols

The solutions for remote-controlled protocols include 10BASE-T1S, CAN FD light and UART over CAN. These protocols operate in half duplex, allowing non-simultaneous, bidirectional data transmission between two devices. Half duplex enables multidrop capability, where more than two devices communicate on the same bus, requiring only a single networking device in the commander ECU to interact with multiple edge nodes. Figure 7 illustrates an example of a multidrop topology.

10BASE-T1S, CAN FD light and UART over CAN differ in speed, payload capacity and number of nodes in the multidrop and bus topologies. Table 2 compares these protocols.

Figure 8 shows the difference between the round-robin and commander-responder topologies. The round-robin topology operates cyclically, where each node has a dedicated transmission opportunity per cycle based on its node ID. This automates arbitration, but requires mediation to ensure that priority or time-critical data is not delayed by low-priority data on the bus. The commander-responder topology requires the commander ECU to prompt downstream nodes before sending data on the bus. The order of transmission is up to the commander ECU rather than being dictated by node ID.

10BASE-T1S, standardized by Institute of Electrical and Electronics Engineers (IEEE) 802.3cg, uses the Remote Control Protocol, which is standardized by Technical Committee 18. It operates at 10Mbps and in a round-robin multidrop topology. As an Ethernet protocol, 10BASE-T1S can incorporate Ethernet features such as Media Access Control Security (MACSec), Time-Sensitive Networking (TSN), Audio Video Bridging (AVB) and Power over Data Line (PoDL). Table 3 describes these four features. Additionally, systems already using a high-speed Ethernet backbone may benefit from simplified software with an all-Ethernet network.

CAN FD light, a variant of CAN FD based on the International Organization for Standardization (ISO) 11898-1:2024 standard, operates at 1Mbps to 5Mbps. Unlike traditional CAN, which follows CAN arbitration (where nodes transmit simultaneously and the node with the lowest node ID wins), CAN FD light operates using a commander-responder topology. Edge nodes employ CAN FD light responders, while commander ECUs use CAN FD light commanders or CAN FD transceivers. Since many preexisting architectures already use CAN FD transceivers to communicate with edge nodes, integrating CAN FD light into current architectures is easy. Achieving speeds >1Mbps requires CAN FD light commanders, however, given controller arbitration phase constraints.

Both the 10BASE-T1S and CAN FD light protocols bridge Ethernet and CAN to other protocols such as SPI, I2C, UART, GPIO and PWM (see Figure 9). This bridging enables remote control of multiple sensors and drivers through 10BASE-T1S and CAN FD light, making both solutions versatile across various end applications.

UART over CAN transmits UART packets over the CAN physical layer (PHY) using CAN transceivers (see Figure 10). Operating at ≤1Mbps in a commander-responder topology, UART over CAN offers a cost-effective solution but relies on UART-based drivers such as an LED, or motor drivers with integrated real-time control and diagnostic features.

Smart drivers with integrated real-time control complement remote-controlled edge solutions by reducing the amount of upstream control requirements. Texas Instruments (TI) offers smart motor drivers with integrated control for sensorless motor systems, including sensorless field-oriented control for brushless-DC (BLDC) motor drivers and integrated current sensing and stall detection for stepper motor drivers. Stepper motors are especially good for remote-controlled edge applications because they require less upstream diagnostic data given the increased rotation accuracy. Table 4 lists some TI devices.