RS485 auto direction control
This is a normal RS485 circuit.
It needs to control direction(RE/DE) pin.
Or you can use this circuit for auto direction control.
I recommend the MAX13487 chip. It is an RS485 chip with auto-direction control.
You don't need to control direction. Just tie direction pin (RE/DE) to VDD (Vcc). This chip helps programmers no longer have to worry about direction-control.