🚀 go-pugleaf

I am familiar with RS-485 from the process control and instrumentation
world.  It is commonly used to connect multiple "field" instruments or
devices to a "control" device.  

RS-485 only sets the hardware and electrical standards as far as I
know.  Using copper wires, typically two twisted pairs of wires are
used (4 wires total).  One pair is designated as the transmit, or TX,
from the main control device.  The other pair is the receive, or RX,
which carries data from the field devices back to the controller.
The electrical signals are bipolar, plus and minus 10 volts if I
remember correctly.  The field devices are placed in parallel, across
the link, to establish a "bus" topology.  Each field device is typically
addressable from the controller; the controller sends out a wake up
signal with the address of the desired field device.  All devices hear
the address and the correct one responds back by placing its data on
the RX twisted pair line.  I remember that the electrical spec. places
a limit of about 6000 feet on the total length of the link.  There
are 120 ohm terminating resistors on each end of the link to suppress
pulse reflections.  I have also used convertors which take the copper
RS-485 link and put it onto two fiber optic strands (TX and RX).  
Multiple convertors can be bussed together on the copper side to appear
as a single RS-485 circuit, with multiple fiber links going out to 
field instruments in radial fashion (star topology).  I currently have
a distributed industrial control system linked together in this manner.

Hope this gives you some information for your application.

Best Luck with your project, Bill