Connecting to Multiple Master Modules with Single Master Projects on Shared J1939 Bus

Chris Litwin 4 years ago in IQANrun updated by Gustav Widén (System support) 4 years ago 3

How does IQANrun or IQANgo behave when you try to connect to master modules that have their own single master project but share a J1939 bus? If I try to connect to them on that shared bus will it give me the option to select which master module/project to connect to?


It depends on the IdTags fitted to the single masters, and it also differs between IQANrun and IQANgo.

If exactly one master modules is fitted with IdTag 0, IQANrun will pick that master module when connecting on the shared CAN bus. 

When no master modules have IdTag 0, IQANrun will bring up a selection dialog.

(either a different IdTag, or IdTag not fitted)

A special case is when all master modules have IdTag 0, then IQANrun will also bring up a menu for selecting module. 

IQANgo (connecting via G11 on the shared bus) is different. 

When there are multiple masters and none of them are address 0, or more than one is address 0, then IQANgo will give an error about "Headmaster not found" 


Thank you for the response. The IQANrun scenarios make sense. If I use all address tag 0 with IQANgo it sounds like I would need to power down one of the modules to be able to connect to one? Would I be able to power it back on after the initial connection?

Thank you,


I think that could work.. at least it gets you past the initial connection. 

And since you are not on the actual diagnostics bus, the master you power up will be silent and won't attempt to communicate with the G11. 

If you were to try two single master applications that have G11 in the application, and connect the diagnostics bus, then I anticipate there will be some problems, as both single masters would try to communicate with the G11. 

For a machine with multiple masters, my general recommendation would be to design the machine as a multi-master system. That way you know you have the system design that the G11 and IQANgo are designed and tested for.