I am currently trying to communicate with a modbus slave through a RS485/Ethernet converter. The slave device is RS485 2 wire, and the converter is RS485 4 wire. As of now, I wired both Tx+ and Rx+ to the slave's Data+ pin and the same for its data- pin. However, when communicating I only get echoes of the master's queries instead of proper answers from the slave. According to [this forum][1] the converter I use might not shut down its receivers when transmitting, thus the echoes I get.

After looking around I found two possible ways to fix the problem:

   - use a converter: either buy it or make it, although I haven't found any projects about this 
     online so maybe making it isn't worth it

   - use something [similar to this isolator for I2C][2], which prevent signals from coming back to their origin


Are those the only possibilities I've got? I feel like buying a converter will be the final solution but I also wanted to know about the ways to go around this problem.

Here's a sketch for more details:

[![wiring sketch][3]][3]

  [1]: https://control.com/forums/threads/modbus-rs-485-4-wire-to-2-wire.17671/
  [2]: https://www.electronicdesign.com/technologies/analog/article/21798879/even-cheapskates-need-reliable-i2c-isolation
  [3]: https://i.sstatic.net/oWjaI.jpg