Protocol Taxonomy¶

Machine communication names often refer to different layers or artifacts.

Visual Model¶

flowchart TD electrical["Electrical interface: RS-232, RS-485"] --> framing["Framing: UART, LIN"] framing --> bus["Data bus: CAN, ARINC 429"] bus --> transport["Transport or transaction: ISO-TP, MIL-STD-1553"] transport --> semantic["Semantic vocabulary: J1939, UDS, OBD-II"] description["Description formats: DBC, ARXML, LDF"] -. describe .-> semantic capture["Capture formats: MDF, BLF, ASC, PCAP"] -. record .-> bus

CAN is a bus and data-link frame format. J1939 is a higher-layer vehicle convention on top of CAN with 29-bit identifiers, PGNs, SPNs, transport behavior, and diagnostics.

UART is a byte framing primitive. RS-485 is an electrical multidrop signaling standard. A protocol such as Modbus RTU can ride on serial framing and RS-485 wiring, but those are not the same thing.

ARINC 429 is a unidirectional avionics data bus centered around labeled 32-bit words. MIL-STD-1553 is a command/response avionics and defense bus with a bus controller, remote terminals, and bus monitors.

USB is a layered host/device system with signaling, enumeration, transfers, classes, and descriptors. It is not comparable to a DBC file.

DBC is a description format for CAN signals. It is metadata about messages, not a bus or physical transport.

schoolbus keeps these distinctions visible so learners can ask whether they are looking at wiring, framing, arbitration, addressing, transport, application meaning, capture format, or description metadata.