I've connected 3 separate networks each with 1 Quantum 434 and 8 Sepam 2000 on Modbus RTU. For Quantum you should use XMIT. It came as Loadable and if you don't have it I can provide it to you. This XMIT will only attache itself as Master on COMM1 in Quantum. Sepam 2000 use an RS-485 port to implement the network. For this reason you have to use an RS232 to RS485 converter. The speed of the network can be up to 19.200 kB