How to detect LIN slave offline?

[ABOLUO]

Basing on S32K144 LIN stack (S32DS for ARM2.2),  If there is on slave, how can the Lin Master detect the issue? 

[PetrS]

Hi,

yes, as already provided here, to detect a LIN slave going offline in a LIN stack:
- Master checks for response after sending a header.
- If no response or error (e.g., checksum), a timeout counter increases/expires.
- After N missed responses, the slave is marked offline.
- Optionally, use diagnostic frames to ping the slave.

BR, Petr

[ABOLUO]

Is there same APIs to get the timeout flag? I try to use l_ifc_read_status, but 'error_in_response' flag not set when I power off the slave.

Thanks a lot.

[mary22evans]

A LIN Master detects a missing slave primarily through response timeouts. When the master transmits a frame header and expects a response from a specific slave, it monitors for the slave's data within a defined timeframe. If no response is received before the timeout expires, the master concludes the slave is absent or non-functional. Additionally, checksum errors on received frames, though not directly indicating a missing slave, can signal communication issues. For a more definitive check, the master can utilize LIN diagnostic services (e.g., "Read by Identifier") to actively poll a slave; a lack of response CredibleBH to such a request further confirms its absence. The S32K144 LIN stack typically handles these timeout mechanisms, providing status flags or callbacks to the application.

[ABOLUO]

Thanks for your suggestion. It can be solved by diagnostic services, but I think it's better to use normal frame to solve it. Trace the function "lin_lld_timeout_service()", I found in the file "lin.c", line 567,  'Received part of data but not completed' can trigger 'LIN_LLD_NODATA_TIMEOUT' event, but 'no data received' can not trigger it, is this behavior expected? or it's the issue?

[ABOLUO]

Now, I use the API 'l_ifc_read_status' to check the 'SUCCESSFULL_TRANSFER' of a special frame, I get the wanted result.