If RS485 wants to be seamlessly upgraded to Ethernet, there includes many key technologies. It needs to seamlessly combine Ethernet technology and RS485 communication protocol for transition. These include: 9-bit technology, framing technology, master-slave mechanism, etc.
9-bit technology: In 485 mode, users can send 9-bit data. And sometimes the 9th bit is used to indicate whether it is a data frame or an address frame. Since Ethernet is 8-bit data during network communication, there is no space that 9 bits can be placed. So how to transfer the 9-bit of 485 becomes a problem. It is understood that Shanghai Zhuolan's serial device server uses a protocol called realcom, which can convert RS485 9-bit data format into Ethernet 8-bit data.
Framing technology: Framing is a key technology in serial to Ethernet (including RS485 to Ethernet), that is, when the serial device server receives the data of the serial device, when the data is packaged and forwarded to the Ethernet, if each byte is packaged into one packet, obviously the efficiency is too low, so how many bytes are appropriate to be packaged. This requires the user to set a parameter called the longest packet length and the longest packet interval.