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Multi master no contact with J1939

RobertRoss 1 year ago in IQANdesign updated 1 year ago 2

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I know this questions has a few answers already, but none of them seem to be working for us.

I now have separate J1939 'modules' assigned for each master and their addresses identical to their masters, and have tried connecting the J1939 bus to both the Diagnostic & master bus, but with no luck. I still get no contact with one module and the second is not found.


Any direction or help would be appreciated.

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Here is what I've learned from my trials with J1939 multi-master systems:

J1939 messaging tips


  1. JFINs should be assigned to J1939 module they are coming from. In multi-master JFINs should be in application for module they are being sent to.
  2. JFOUTs should be assigned to the J1939 module they are going to. In multi-master JFOUT should be in application for module they are being sent from. Source address for JFOUT should be address of module they being sent from (if JFOUT are in proper application, setting source address to "Default" does this).
  3. If communication is not 2 way between both J1939 modules there will be no contact for the module that is not sending a message (same thing will happen if the message isn't being received properly).
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some minor issues to work out, but I owe someone a beverage...THANKS!