RS485: is "Y" multidrop allowed?

Question

I imagine that the proper way to implement an RS485 multidrop bus is the following:

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What happens if, in order to save cables, I connect the same 5 nodes above using this other topology?

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• Will it works?
• If no, why?
• If "maybe", under which circumstances will it work?

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P.S.: yes! I know that MEGA has three Serials and, as such, I could implement two different BUSses (1: Mega<->Mega<->Mega; 2: Mega<->Nano<->Nano), but this will increase the complexity of the software I'm running, as it needs some hacking in order to play nicely with two distinct RS-485 busses;

P.P.S.: This is the bus discussed in this other question

Answer 1

At low speeds and short distances that won't be a problem.

At high speeds (megabits per second) and long distances (hundreds of meters) you may get reflections unless you get the termination just right.

• Largato: Can you please tell values you think is reasonable to call "short distance" and "low speed" in this context?
• Majenko: @Bacco tens of meters and 115200 baud, I'd call short distance and low speed.
• Largato: Thanks for your feedback!