Technical data

Fieldbus Communication • 177
ETHERNET
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
4.1.3.2.1 ETHERNET
ETHERNET address (MAC-ID)
Each WAGO ETHERNET (programmable) fieldbus coupler or controller is
provided from the factory with a unique and internationally unambiguous
physical ETHERNET address, also referred to as MAC-ID (Media Access
Control Identity). This can be used by the network operating system for ad-
dressing on a hardware level.
The address has a fixed length of 6 Bytes (48 Bit) and contains the address
type, the manufacturer’s ID, and the serial number.
Examples for the MAC-ID of a WAGO ETHERNET fieldbus coupler (hexa-
decimal): 00
H-
30
H-
DE
H-
00
H-
00
H-
01
H.
ETHERNET does not allow addressing of different networks.
If an ETHERNET network is to be connected to other networks, higher-
ranking protocols have to be used.
Attention
If you wish to connect one or more data networks, routers have to be used.
ETHERNET Packet
The datagrams exchanged on the transmission medium are called
“ETHERNET packets” or just “packets”. Transmission is connectionless; i.e.
the sender does not receive any feedback from the receiver. The data used is
packed in an address information frame. The following figure shows the struc-
ture of such a packet.
Preamble ETHERNET Header ETHERNET Data Check sum
8 Byte 14 Byte 46-1500 Byte 4 Byte
Fig. 4-9: ETHERNET-Packet
The preamble serves as a synchronization between the transmitting station and
the receiving station. The ETHERNET header contains the MAC addresses of
the transmitter and the receiver, and a type field.
The type field is used to identify the following protocol by way of unambigu-
ous coding (e.g., 0800
hex
= Internet Protocol).