Switch a serial tab to CAN mode when the connected adapter carries CAN frames. Select the adapter and bus settings before interpreting traffic.
Choose the adapter
- SLCAN-compatible adapters: classic CAN with up to eight payload bytes, a Monitor bitrate control, standard/extended IDs, and remote requests.
- mjbots fdcanusb: classic CAN and CAN-FD with up to 64 payload bytes. Configure its rates and Bus On state in the adapter console before connecting.
Follow the dedicated adapter guide before reading or sending. The adapter firmware must implement the expected protocol. For CAN-FD, preserve FD and BRS indicators in the result.
Decode signals
Provide the database for the bus or ECU: DBC, KCD, SYM, or AUTOSAR XML.
Embedder prepares a Monitor profile under .embedder/can/. Select that profile in the CAN toolbar and enable Decoded. The Monitor uses the prepared profile rather than opening the source database directly.
Check the message ID, standard or extended format, length, byte order, scaling, and units against a known frame. If no database exists, review a proposed source-code interpretation before using it.
Send a test frame
CAN transmissions can change ECU state or command actuators. Identify the bus, receiver, ID, payload, and expected effect before sending.
id#data in the CAN send input:
This example represents ID 0x123 and four payload bytes; replace it with the reviewed frame for your bus. Follow the SLCAN send rules for extended IDs and remote requests, or the fdcanusb send rules for explicit classic/FD/BRS flags. A submitted frame does not prove the receiving application acted on it.
Read and decode first. Send only when the test explicitly requires it.
Interpret results
Keep raw bytes with the decoded values. A frame without a matching definition remains raw; do not assume its application meaning.
Higher-level protocols such as J1939, CANopen, ISO-TP, or UDS need their own project definitions. Raw CAN framing alone does not identify them.
Troubleshoot
- No frames: check the adapter firmware, bus bitrate, wiring, termination, and bus activity.
- All frames remain raw: confirm the selected profile and matching message IDs and lengths.
- Wrong decoded values: verify byte order, bit positions, signedness, scale, and offset.
- Adapter errors: inspect the reported bus status before transmitting or changing configuration.
Use a logic analyzer or oscilloscope when you need to inspect the electrical signal. 
