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Master to master comunication efficencies?

Forrest 3 years ago in IQANdesign updated by Gustav Widén (System support) 3 years ago 1

I am considering a MD4, MC42 and MC41 system vs. the current MD3 with a pair of  XA2 modules for a revamp comming up.


Does version 5 comunicate between masters more efficently than V4?

How about V6, and if so, about when can I expect it?


How many packets of information can I send before the bandwidth gets clogged and performance is impacted?


Is there a way to set J1939 inputs to autmatically generate when an J1939 ouput is created in another master?

If not, please consider it for a future revision.


There is no difference in the bandwidth usage for a multi-master system between versions 4 and 5, the APPOUT/APPIN protocol (Master bus) is exactly the same. 


The APPOUT/APPIN:s is a protocol designed primarily for safety related communication, and because of the way we designed it there is a lot of overhead compared to more high-density protocols, e.g the the expansion module bus. 

Each APPOUT you add will take up one full-length CAN frame (DLC 8) with extended identifier (29bit). The bus speed is 250 kpbs, so that translates to about 0.7 ms on the bus for each APPOUT/APPIN combo. 

Sending one APPOUT to two APPIN:s generates two messages. 


Note that if you actually use the APPOUT/APPIN:s for safety related real-time data, you would set them to send continuously with a known time instead of the "on change" setting, so then it becomes relatively easy to predict the bus load. 



There is no feature to do exactly what you request with auto-generating J1939 messages between masters, but there is another feature coming that might help some, the DBC file import:

http://iqan.userecho.com/topic/529474-dbc-file-import/