Startup Multi-Master

Jonas Bengtsson 2 years ago in Master modules updated by Gustav Widén (System support) 2 years ago 1

If an application have a MD4 and MC4X and they are connected as multi-master. How does the startup looks like? Will the MC4X start communicate with peripherals as soon its booted or does it wait until MD4 is booted?


Both masters will start running their applications independently of each other before the multi-master communication is up and running. Meaning they will read local and expansion inputs, set local and expansion outputs, and communicate with 3rd party modules on J1939 and generic CAN. 

You can observe this by looking at the system information channel for Multi master state.

The channel will only be in init for one cycle, it then changes to Limited operation, and stays in that state until it changes to OK indicating that multi master communication is up and running.

The IQAN-MC4x will start up after about 500 ms. The IQAN-MD4 is fast for a display but not as fast as an MC4x, the MD4 it is typically running its application after about 1.7 seconds.  (varies with size of the applications)

After the MD4 has started its application, it will take at least another 500-600 ms to set up the multi-master communication. 

A related topic worth mentioning. When a J1939 bus  in IQANdesign is configured to use address claim, no J1939 messages are sent until the address claim procedure is completed.