Ethernet serial servers facilitate network integration with protocols like RS232/422/485 and Modbus. Some provide connections for just a single device. Others can connect multiple devices, or even multiple devices that are using different data communications protocols. No Ethernet serial server is the most appropriate or the most cost effective for every imaginable application.
Serial servers with Power over Ethernet (PoE) not only let serial devices communicate across networks, they will power them as well. This eliminates clutter created by power supplies and cables, and will also let serial devices operate in locations where there is no easy access to power outlets.
Like serial RS-232/422/485, Modbus remains a very popular and very useful data communications protocol. As with serial, the Modbus protocol can be converted for Ethernet use.