RS485 feeds combine or keep separate?

[dstra1]

I currently have 2 B2A8S20P JK BMS hooked to 24V DIY batteries. I also have 2 BD6A20S15P JK BMS running another pair of 24V DIY batteries. I purchased the appropriate RS485 adapters and have them plugged into the GPS ports. Running dubs-serialbattery I have the data from the 4 BMS coming into my Pi running VenusOS. They combine in the battery cabinet with a powered USB hub before going to the Pi so there is only one port used and they do not draw power from the Pi USB port.

My question is if there is an advantage or good reason to combine the RS485 feeds before the adapters into one (or two)? One difference I see is that in VenusOS each of the batteries would show up as battery modules and it would take up less USB ports. The other is that I don't need to buy the RS485 adapters for each BMS. Anything else?

I'm going to add 2 more BMS to the system for my latest batteries. Either the same BD version or maybe PB series. Before I purchase more BMS and the adapters I'd like to see if there is a compelling reason to go one way or another.

Thanks in advance for any sage advice!

 

[ksmithaz1]

USB devices, can float on the bus, depending on enumeration. If you change the modbus ID and put them all on one you know. You can only poll one device at a time on a shared bus.

 

[kommando]

RS485 is designed to be daisy chained, so you can add more to the USB but not all together but in a chain with the last in the chain having a 120ohm resistor bridging A and B. With a typical 15 sec poll they will all be able to send their data within the 15 secs.