There are a ton of communications systems, just to name a few out of my head: RS232, RS485, USB, PS/2, Centronic, Firewire, I2C, SPI, JTAG, SPDIF, LIN, FlexRay,

There are a ton of communications systems, just to name a few out of my head: RS232, RS485, USB, PS/2, Centronic, Firewire, I2C, SPI, JTAG, SPDIF, LIN, FlexRay, AS-i, Component, IO-Link. CAN is also used outside of Automotive. Even Google is using it for their servers, or better for the redundant power supplies for their servers. HP is using it in their printers and copy-machines. The thing is, there is always a technology you don't know. There is your preferred search engine and Wikipedia to help you with that knowledge, these days. PS: These days almost everybody miss the difference between Ethernet and TCP/IP. While everybody talks about Ethernet most of the time TCP/IP is meant, not Ethernet.