AUTOSAR

Posts 1-5 of 5

Alexandru Nastas
The company name is only visible to registered members.

Question about IPduM
Hello, I'm new to Autosar. I have some questions about the communication stack.
What is IPduM used for ? I mean I know that it does Mux/Demux of I-PDUs, but in what manner ?
What are the static and dynamic parts in an I-PDU and what is the role of the selector field ?
Why do we need multiplexation ?

Thank You
- 03 Feb 2010, 11:24 am
Alexandru Nastas wrote: > Hello, I'm new to Autosar. I have some questions about the > communication stack. > What is IPduM used for ? I mean I know that it does Mux/Demux of > I-PDUs, but in what manner ? > What are the static and dynamic parts in an I-PDU and what is the > role of the selector field ? > Why do we need multiplexation ? > > Thank You
Oliver Meili
The company name is only visible to registered members.

Re: Question about IPduM
Hello,

the IPduM is used to handle so called Multiplex Messages on the CAN bus. They are used to save CAN-IDs by using more than one signal layout for one message. The selector then defines the layout and the signals are typically part of the dynamic part of the message. Additionally it is possible to have a common set of signals for one message (the static part).

Hope this helps

Oliver
- 03 Feb 2010, 1:01 pm
Oliver Meili wrote: > Hello, > > the IPduM is used to handle so called Multiplex Messages on the CAN > bus. They are used to save CAN-IDs by using more than one signal > layout for one message. The selector then defines the layout and the > signals are typically part of the dynamic part of the message. > Additionally it is possible to have a common set of signals for one > message (the static part). > > Hope this helps > > Oliver
Alexandru Nastas
The company name is only visible to registered members.

Re^2: Question about IPduM
Thanks a lot, Oliver

But still got some questions like : what is a signal layout (couldn't find the definition in specs), what is the common set o signals used for (in the static part) ?

I'm sorry for the stupid questions, I read the COM and IPduM specs, but did not find the answer to these questions. I'll try to see CAN TP, CAN IF specs also, maybe better luck . Thanks a lot.
- 03 Feb 2010, 1:36 pm
Alexandru Nastas wrote: > Thanks a lot, Oliver > > But still got some questions like : what is a signal layout (couldn't > find the definition in specs), what is the common set o signals used > for (in the static part) ? > > I'm sorry for the stupid questions, I read the COM and IPduM specs, > but did not find the answer to these questions. I'll try to see CAN > TP, CAN IF specs also, maybe better luck . Thanks a lot.
Oliver Meili
The company name is only visible to registered members.

Re^3: Question about IPduM
Hi Alexandru,

this is not an AUTOSAR specific topic, but a matter of how the CAN bus is used in the automotive industry...

The information in CAN messages in encoded in signals, which define the information exchanged among ECUs. Typically, a CAN message with a given CAN-ID has a defined set of signals, while the signal layout (or to be more correct, the signal mapping) describes at which position a signal is transmitted in the message. Using multiplexing, it is possible to transmit more than one signal at one and the same location in the CAN message by transmitting the first signal at one time instance and the second signal at a second time instance. All signals which are not the same between the two time time instances are the dynamic part of the message. The two different cases are identified by means of the multiplexor or selector signal. There might also be a common part in a multiplex message which AUTOSAR refers to as static part.

Check any good CAN reference for the automotive industry to learn more about multiplex messages.

BTW: not many OEMs actually use multiplex messages, thus you might never really require the use of the IPduM...

Best regards

Oliver
- 03 Feb 2010, 2:08 pm
Oliver Meili wrote: > Hi Alexandru, > > this is not an AUTOSAR specific topic, but a matter of how the CAN > bus is used in the automotive industry... > > The information in CAN messages in encoded in signals, which define > the information exchanged among ECUs. Typically, a CAN message with a > given CAN-ID has a defined set of signals, while the signal layout > (or to be more correct, the signal mapping) describes at which > position a signal is transmitted in the message. Using multiplexing, > it is possible to transmit more than one signal at one and the same > location in the CAN message by transmitting the first signal at one > time instance and the second signal at a second time instance. All > signals which are not the same between the two time time instances > are the dynamic part of the message. The two different cases are > identified by means of the multiplexor or selector signal. There > might also be a common part in a multiplex message which AUTOSAR > refers to as static part. > > Check any good CAN reference for the automotive industry to learn > more about multiplex messages. > > BTW: not many OEMs actually use multiplex messages, thus you might > never really require the use of the IPduM... > > Best regards > > Oliver
Alexandru Nastas
The company name is only visible to registered members.

Re^4: Question about IPduM
Hello Oliver,

Thanks for the answers. Now I got some ideas about this topic.

Thanks again :)
- 04 Feb 2010, 10:50 am
Alexandru Nastas wrote: > Hello Oliver, > > Thanks for the answers. Now I got some ideas about this topic. > > Thanks again :)

AUTOSAR

Question about IPduM

Re: Question about IPduM

Re^2: Question about IPduM

Re^3: Question about IPduM

Re^4: Question about IPduM