The UDS (Unified Diagnostic Services) protocol is a diagnostic standard used in modern vehicles that enables communication between diagnostic tools and electronic control units (ECUs) through the CAN network, allowing functions such as data reading, fault code clearing, and access to internal vehicle information; to interpret CAN frames under UDS, it is necessary to understand that each message contains an identifier (ID) and a series of data bytes where the second byte represents the requested service (for example, 0x10 for session control or 0x22 for data reading), followed by specific parameters such as DID identifiers, while the ECU response is identified by adding 0x40 to the requested service (for example, 0x62 as a response to 0x22) or by a negative response code (0x7F), which indicates an error; additionally, when the data exceeds 8 bytes, the ISO-TP protocol is used to segment the message into multiple frames, which is essential for proper interpretation; in this learning and analysis process, tools like the CAN BUS multiplex trainer are very useful, as they allow real-time visualization of CAN frames, making it easier to understand the structure of each message and helping to accurately interpret the data transmitted over the CAN network.
