How do I route audio to the AD2428 A-port Upstream?

The reason I'm asking is that I've come across an OEM product that appears to work use A port.
I'm trying to understand what I'm may be missing.
(My existing system I configured using B port is also imitating the OEM.)

Could it actually be that the second module is operating as an independent A2B network with its own main node,
rather than being part of the same network? In other words, are there cases where two separate A2B networks coexist without sharing a single network topology?
(There is clearly only one audio generator, and it is outputting properly through port B.)

Thank you
LocoField

AD243x series A2B does offer running two parallel, i.e. two synchronized but independent  busses where all the sub nodes run off a common clock, to get 64 channels.  But both the main (root) nodes are still a B port only setup.

It might be possible with some serious register hacking to make a main node have a functional A port but I kind of doubt it because of the way the clocking and data movement happen inside the part.  Best as I can tell that's all in internal state machines and you can't change it.  

I've been thinking about this for a few days, but I think I've been overthinking it.

I think my board would be the sub node if I use a and b together.
It is true that I send the audio from my board, but I just need to wait for it to be set up as a sub node, receive the bclk, and then send only the audio, right?

not quite sure I follow your question, but the general answer is you can only have the one main node, and main nodes do not have an A port.  So unless you change the main node to be whatever it is you're adding then whatever you're adding must be a sub node with and A and B port (unless last node, then no B needed).

I think though I'm not answering your question.

Thank you, your answer was very helpful.

The conclusion was that I initialized a subnode as the main node across the entire network without waiting for discovery from the OEM main node.
I just left it alone, and eventually, a discovery request came from the main node...

A2B_NODE (0x29) is 0x20 (Node Discovered (5:DISCVD))

Thank you, your answer was very helpful.

The conclusion was that I initialized a subnode as the main node across the entire network without waiting for discovery from the OEM main node.
I just left it alone, and eventually, a discovery request came from the main node...

A2B_NODE (0x29) is 0x20 (Node Discovered (5:DISCVD))