EXPERT has a lot of various models to do conversion, where you can make the coise between the isolation side and extension of protocol (RS485 only or adding RS422)
Take for instance the cheapest model, our EX9520, This is a high-performance low-cost RS-232 to RS-485 converter, packaged for convenience in a compact DIN rail mounted unit. One of the unique features of the product is its self tuning circuitry “Auto Pro”. This permits the unit to auto-detect and auto-tune to any baud rate and data format over the whole network to which it is connected. The added benefit of this technique is that there are no hidden dip switches to set (*). All devices on the network can operate at the maximum bandwidth of up to 9600 Bps. With this feature the user may link PLC's, RS-485 devices, RS-232 devices and even other PCs over a standard RS-485 network. This can be achieved even if the data format and baud rate of those devices are different. The baud rates are from 3 00 baud to 115k baud covering the majority of standard serial communication devices. Up to 256 devices can be supported on a single network.

Each unit is isolated to 3000 volts offering high-level of electrical protection to devices on the network. For easy mounting and connection., the modules may be mounted on a DIN rail, panel or directly onto the wall. The EX9520A offers the same basic features as the EX9520 but with the added option of selecting either RS-485 or RS-422 protocol (dip switch). All other specifications and performance details are the same.
The EX9520R and EX9520AR are adding Isolation to the RS485 side, while offering the same features.

Standard RS-485 networks operate over distances of 1.2km (4000 feet). To extend the distances and provide high voltage protection to certain parts of the network a EX9510 Repeater can be added to the network. The EX9510 offers the same self tuning circuitry as a EX9520 and can support multiple baud rates and data types. Complementing the EX9520, the EX9510 offers the same level of isolation up to 3000 volts.