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Automotive Diagnostics — Tester Present
Jun 27, 2021
Consider tester present service as a way to indicate to the server/ECU that the client/tester is still connected and working. It can be viewed as a heartbeat for servers to recognize if there would be any diagnostic activity
Different sub-functions supported by the tester present are
Important points about tester present
- If the server/ECU is present in a non-default session, the client uses the tester present service to maintain the server in a non-default session.
- To maintain the ECU in non-default sessions, the client keeps sending tester present periodically.
Examples of message flow
Request message
Positive Response message
Negative response message
Supported Negative response codes:
