In my project i use 3 arduinos to communicate over RS485.
I am still at prototype, but o got an issue wich i solved, and dont undestand why.
1 master 2 slaves.
i am using those RS485 modules sold everywhere for arduinio.
The behaviour before:
Master sends message to slave 1 and receive wrong response.
Master sends message to slave 2 and receive wrong response.
After some trial and error, i discovered that if i connect the A to +, using a resitor
and B to - using other resistor, i got the system talk fine.
My question is: Why do i need to connect A and B to + and - can some one explain me?
Looking at module diagram, this connections are already made.
I used 220ohm resistors. (were the ones i had at hand)