Multiframe Message Implementation

[manumohan]

Hi,
im facing a  protocol implementation problem for J1939 which is specified in
SAE I N T E R N A T I O N A L SURFACE VEHICLE RECOMMENDED PRACTICE ( J1939-21 ) REV APR 2001 for SAE J1939 Data Link Layer Implementation section 5.10.3.5 and
5.10.4 in which i have to implement a CAN Message with 2 Periodicities.i.e I have to send a Broadcast Announce Message(BAM) with 5 sec periodicity which will be an announcement for the Nodes that a Multiframe message(Message with 24 bytes) which consisit of 3 frames
coming at 100 ms periodicity.i.e
1.bam messagecoming at 5000ms
2.Tpdt frame follwed by bam at 5100 ms
3.Same tpdt with different data at 5200ms
4.One more tpdt at 5300ms
5.tpdt's  transmition is interrupted till next bam coming at 10300ms then the tpdt cycle proceeds.
The above mentioned cycle is required to initialise some of the Nodes in a network of ECU's.
so i cannot initialise tpdt with fixed periodicity and data content.
Currently Channel api is used for the application to implment CAN.
My question is:
1.is it possible to implement the same with frame API's?
2.How can i modify the channel api to implement the same ?
 
Thax and Regards
Manu Mohan
 

 
 

[Sputnikrent]

Hi Manu Mohan, It does not look like you should have too much trouble setting that up in the Channel API. You will want to set the CAN channels up in MAX to specify the different&nbsp; messages that you have. This can be found in the CAN Channels section (pg 34) of the NI-CAN manual that can be found <a href="http://digital.ni.com/manuals.nsf/websearch/6C57190E7F6553A986257205006D273A" target="_blank">here</a>. Let us know how it goes!

[manumohan]

Hi Rasheel,
Thax for the info.The problem here is not about creating a message.I already have 2 messages which is defined in a dbc file which i imported to max.
My issue is ,these messages are dependent to each other and one message have a variable periodicity with multiple data for same signal.
Do you think this can be addresses in the driver layer itself instead of moving up to the API Level ?

[Sputnikrent]

Can you give me an example of what you mean by one message depending on another? How are they dependent? Unfortunately you cannot make any adjustments in the driver layer, we will have to use the API to configure things.