178 Ethernet module User’s Manual
Chapter 7 RAS Information
7
Preamble (7 bytes)
Signal used to synchronize reception
SFD (Start Frame Delimiter) (1 byte)
Remote station address (6 bytes)
Local station address (6 bytes)
Ethernet type (2 bytes)
0800H:IP, 0806H:ARP
IP header (20 bytes)
UDP header
(8 bytes)
TCP header
(20 bytes)
UDP data field
(up to 1472 bytes)
TCP data field
(up to 1460 bytes)
FCS (Frame Check Sequence) (4 bytes)
32-bit CRC code for the sections of the packet other than
the preamble, the SFD, and the FCS. (Packet error
detection)
IP datagram
(46-
= Data field of
the packet
flowing on the
transmission
path
Packet
flowing on
the
transmission
path
(72 to 1526
bytes)
IP data field
(up to 1480
bytes)