Real-time Ethernet: standard hardware vs. specific hardware
Different processes can be used to make Ethernet compatible with real-time. The simplest form of real-time protocol is placed above the TCP/IP layer and is based on a polling mechanism, or time slot process (image below, left). Real-time protocols in which conventional protocol stacks (layers 3+4, transfer and network layer) are used in real-time protocol (image below, center) are more efficient. An additional increase in performance is possible by processing protocols in hardware (image below, right). Some real-time Ethernet protocols use their own Ethernet frame format and are therefore only compatible with Ethernet on the physical layer. On the basis of performance, all real-time Ethernet protocols shown in the image are commonly implemented in specific hardware, not only the version in the right figure.