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My requirement is to receive/send more than 8 bytes from 29 bit CAN id. I'm using TP layer for this. Is there any library functions for receiving the can data which is from 29 bit id? Ex: 0x1CDA00FE is tester and 0x1CDAFE00 is server.

Arulkumar
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  • What do you mean? The data part of CAN messages are maximum 8 bytes, no matter the length of the address field. Unless you are talking about CAN-FD. – matli Mar 14 '18 at 20:59
  • @matli, bus type is CAN (500 KBPS). I'm not talking about CAN - FD. If you want to transmit more than 8 bytes data in CAN bus, Transport protocol (ISO 15765) will be the medium to transmit the data. – Arulkumar Mar 16 '18 at 10:57
  • Ah, sorry. I have very limited experience with ISO-TP, and didn't even think about its existence. Can't help you there I'm afraid. – matli Mar 16 '18 at 13:09

1 Answers1

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non CAN-FD protocol on Data Link Layer does not support payload greater than 8 bytes. Payload in TP greater than 8 bytes is handled as consecutive frames, and usually are incorporated in a packaging protocol, like UDS.

If this is a diagnostic message ID, and you have diag layer (UDS/KWP) configured on this message, there is a complete diag library in CAPL to send/receive diag requests on the configured Diag Layer.

But to do this "by hand" (I do not know what protocol uses your message IDs to send consecutive frames, like in UDS) :

Receiving

message 0x1CDA00FE msgContainer; /*Create/ define an arbitrary instance of CAN message element*/

Here is how you capture the first iteration of the consecutive frames sent (all of them will be 8 bytes, but you will wait for them as individual 8 byte messages until the intended TP layer payload is completely sent to you). So you basically repeat this snippet 6 times (if your TP payload is 6*8=48bytes long), and do with the msgContainer (message with your payload) whatever you want, until the next one comes. 

testwaitformessage(0x1CDA00FE,1000); //wait for the message ID to arrive in 1s
testGetWaitEventMsgData(msgContainer); /*Capture the message content from tail to toe in the msgContainer*/
write("The Byte(0) selector of the captured message for example selects the first byte of the 8 byte payload: 0x%X",msgContainer.byte(0)); // see message selectors for more options

Sending:

byte qword QPayload=0x11223344x55667788; /*You can do with byte array also, I don't fancy to write fors now*/
message 0x1CDAFE00 messagetoSend;
messagetoSend.qword(0)=QPayload;
output(messagetoSend);

/*Prepare another payload to send as the next consecutive frame*/
...
VioletVynil
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