It's easy to use RS485 devices with softwareSerial library.
You just have to add another output pin to the pin 2 and 3 of the 485 driver to enable/disable transmission.
So from, considering the 485 drivers wire it in that way
pin 1 : TX
pin2/pin3 linked together. Enable/disable tranmission
pin 4 : RX
pin 5 : 5V
pin 6 : A positive RS485 signal
pin 7 : B negative RS485 signal
pin 8 : ground.
Really easy to use.
It's better to add a the first and last devices an 120ohm resistor between A and B.
Hope it can help you.