Multidrop RJ45 RS485 connectors

I would have concerns about either module creating a standing wave which reflects energy back that creates false bits because I see either as more of a star topology where each RJ connector is the beginning of 'stub' exiting from a common point.

How_is_this_not_effectively_a_Star_network.jpg


Yes, the connectors are physically separated by mm or inches of tracing, but daisy chaining puts devices in parallel. each of which is at some distance from each other, there is a clear end on each end, unlike a star that does not have two ends.

One of the 'rules' of RS-485 is to limit stub or star wiring.

It might be that reflections are not a problem at internal-to-the-panel distances. But it goes against conventional wisdom in 485 networking.
 
+1 danw

What makes RS-485 more resistant to noise is to work by current, circulating an appreciable intensity through the cable, and this is only fulfilled with a daisy chain connection and the resistors at the ends.
 
I'm totally going to try the red lion product on DSI multidrop if I am ever forced to use it again. The Powerflex 523/525 rj45 connectors are utter garbage to try and terminate as a daisy chain.
 

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