J1939 Comms Between masters

Carl 4 years ago in IQANdesign updated by Gustav Widén (System support) 4 years ago 1

Hi Guys,

Is it still the case that if you have multi PLC's say MD4, MC41, MC42 that to transmit from say the MD4 to the MC42, you have to create a J1939 Generic device copy of each module or is there a better way now? Also, if say we have the engine connected to the MC42 but want to read some engine CAN messages on the MD4, is there an easy way or lots of JPOUTs and JPINS between modules?

Yes, the most efficient way for sending signals between masters is by setting up your own J1939 communication, as in this post

Using the Master bus with APPOUT and APPIN is easier, but eats a lot of bandwith. 

Values from e.g. an MC4x that is showin on the Display page on an MD4 is sent automatically over the Diagnostics bus. 

The best method for a J1939 engine is to have both masters connected to the bus with the engine. To benefit from e.g. the DM1 viewer on the MD4, the MD4 must be connected to the engine. At the same time, you probably want to read a few signals like engine speed directly on the MC4x. But if you are considering having just one of the masters connected to the engine, using the CAN routing feature on the MC4x is the second best, then you avoiding having to set up JFOUT to the other master