Some systems may include multiple nodes that communicate data between one another between different parts of the system. In some systems (e.g., vehicle systems), each node may be, for example, an electrical control unit (ECU) that controls a specific part of the system. For example, one node may control a specific part of a system (such as a wheel braking system) and may rely on a sensor measurement taken at a different node that controls a different part of the system (e.g., a brake pedal control system). Nodes may communicate data between one another by driving (i.e., transmitting and receiving) data across a communication bus. In some systems, rather than include a dedicated communication bus between two communicating nodes, multiple nodes in the system may communicate with one another via a single shared communication bus (e.g., a single communication bus that is shared by multiple nodes in the system). For example, a wheel braking system may communicate with a brake pedal control system across the same communication bus used by a cooling system to communicate with an engine propulsion system even though the wheel braking and brake pedal control systems rarely or never communicate directly with the cooling and/or the engine propulsion systems.
In some systems, nodes may communicate across a single shared bus according to a message-based protocol, such as a Controller Area Network (CAN) protocol, a FlexRay™ protocol, an Ethernet protocol or another type of message-based communication protocol. Message-based protocols may minimize and even prevent data communication between two nodes from interfering with the data communication between two different nodes. Message-based protocols may eliminate the need for a central (e.g., host) computer to manage communication data on the bus by instead relying on timing (e.g., controlling when a particular node can communicate on the bus) and/or message identifiers (e.g., headers within the data that identify the sender and recipient of a data communication) defined by the protocol.
Message-based protocols may define communication between nodes using low voltage differential signals. Two or more nodes may communicate data between each other by transmitting and receiving differential signals across the bus. The polarity of a low voltage differential signal at a given time may define the logic value (e.g., a one or zero for binary data) of the data being transmitted. For example, a transmitting node may include a bus driver that drives a low voltage differential signal (e.g., as the difference between two voltage signals) across one or more signal lines of the bus. The bus driver of a receiving node may receive the two voltage signals from the one or more signal lines of the bus and determine, based on the difference in voltage between the two signals, a single low voltage differential signal. Based on the polarity of the low voltage differential signal, the receiving node may determine the data being transmitted being transmitted across the bus.
While a single shared communication may offer the advantage of limiting the number of electrical connections (e.g., wires) used to communicate data between nodes of a system, a single communication bus may have some disadvantages. For example, by way of physically connecting to the bus, each node connected to the bus is electrically coupled (i.e., connected) to every other node connected to the bus. As such, each node on the bus inherently shares an electrical connection with every other node connected to the bus and may be susceptible to over-current conditions caused by every other node on the bus. In other words, a single node on the bus could cause an over-current condition (e.g., by way of a short circuit, incorrect design, excessive load, or another factor) on the bus that either damages or otherwise causes other nodes connected to the bus to malfunction. In addition, the wire harness that holds the bus may cause an over-current condition at the bus that has the potential to damage the nodes connected to the bus. For instance, an over-current condition may arise on a bus when a bus wire of a wire harness inadvertently comes in contact with other electrical wires or metal parts of a supporting mechanical structure due to vibrations, collisions, and/or failures of the supporting mechanical structure.