USR-TCP232-304 is a RS485 serial server with small size and controllable cost. It realizes the function of RS485 to Ethernet two-way transparent transmission; it has 1 Ethernet port, 10/100Mbps rate; supports timeout restart, DHCP automatically obtains IP DNS domain name resolution, remote upgrade, virtual serial port function; support custom heartbeat package to prevent dead links; custom registration package to detect connection status.