All our interfaces support standard Modbus RTU protocol over RS485 network and therefore you can use Modbus to control and read parameters of the indoor units.
If you wish to use a RS232 network then a RS232 to RS485 gateway is required. We recommend our Modbus gateway RTD-DSX (click here for further information).
For any other communication protocol and network type a gateway/adapter to Modbus over RS485 is required.
See these articles for further information: