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Answered

JFIN longer than 8 bytes

Antonio Dingoma 4 years ago in IQANdesign • updated by Gustav Widén (System support) 2 months ago 9
Hello!

Is it possible to read J1939 messages larger than 8 bytes? I find no way of doing this. When adding JPIN's to the JFIN, maximun bit offset is 64, and there is no option for setting a longer message size. Are segmented messages not suported? It would be used to read a 16Byte broadcasted message.

I'm on IQANdesign 3.18 , Aplication for MD4

Thanks a lot!
+1
Answered
Segmented messages are currently only supported for diagnostic messages in J1939 (DM1/DM2). There are plans on supporting this on any message in 4.x. I'll add your input to the existing feature request.

Was this feature added? I am running version 4.02 and can't find a way to read a 12 byte message.

Application for MD3.


Thanks!

Hi Carl,

This has not been added yet, but it is in the plans for this fall. We hope to be able to implement it in 4.05, which is scheduled for Q4 2016.

I'm trying implant PGN 65209 Trip Fuel Information (Liquid) and it uses 22 Bytes in the frame and no page ID what I can see.Is it possible to read this with IQAN?

It is possible in existing versions, but it comes at the expense of not being able to use the built-in DM1 and DM2 features anymore. 

To read a J1939 multi-packet broadcast on the bus, you could use JFIN:s with PGN numbers 60416 (BAM), 60160 (Data Transfer) and in the application. It will be a bit tricky, the BAM will have the PGN you want in the data field, and this decides what the content in the DT messages will be. You would have to keep track of this to avoid mixing the data. A big disadvantage of implementing your own multi-packet reader on the application layer is that it will take priority over the built in DM1 and DM2 features, these will stop working if you add the multi-packet PGN:s in the application. The project check will say "invalid identifier"  

I have been successful in a few application implementing long messages this way.  However, where i ran into a problem was when the PGN containing the long message (TTI2 or LTFI) is transmitted only on request.  When requesting this message, it appears the IQAN module does not handshake properly.


In a successful request, the sequence should look like this:

However, when using an MD4-10 to generate the request, i get the following result:


It appears the MD4 sends an Abort command rather than the Clear to Send command.


I am not sure if this is by design, unimplmeneted, or a bug.  Please let me know if this might be addressed in the future.  Thank you.


J1939 multi-packet messages are sent either as broadcast starting with a BAM message, or to a specific address using RTS/CTS. 

In existing versions, the IQAN modules only supports reception of certain multi-packet messages, requests to send anything else will be NACK:ed. There is a feature request for adding multi-packet support here: 

https://forum.iqan.se/communities/1/topics/1261-jfin-multi-packet-for-pgns-with-8-bytes-of-data



What you could try is to send the request for these PGN:s to the global address 255, then the engine should respond with BAM instead, which should be easier to pick up. 

Thank you for the clarification and this is understood.

Multi-packet support JFIN/JFOUT implemented in IQANdesign 6.00