BECKHOFF CX1020 - Manual (Page 20)

Product overview
18 Embedded PC
Connection of the Ethernet ports:
Warning
The two Ethernet ports of a basic CPU module must not be connected to the same external
switch!
Schematic structure of the network components:
The CX1020 features two MAC blocks. The first one (MAC1) operates the network interfaces for the Ethernet ports.
The two outputs are connected via a switch. In this way a line structure can be configured as described below. From
an operating system perspective this represents a single connection. The second block (MAC2) operates the
extended PC104 bus. The second physical network connection can be utilised via additional system interfaces. This
requires either a CX1100-0004 power supply unit or a CX1020-N060 system interface. A connection to the E-bus for
EtherCAT terminals is realised via the power supply unit. The CX1020-N060 interface establishes the Ethernet
connection, thereby making a further network interface available.
Note
Only for use in LAN, not for connection to telecommunication circuits.
Operating system perspective:
The operating system only sees one of the connections for the network interface. The status is always connected,
since the switch is connected directly. The internal connection via the PC104 bus extension is shown as the second
interface. If no expansion module is connected, the line is reported as not connected. If the CX1100-00x4 power
supply unit is connected, Windows XPe reports "restricted or no connection". This behavior is normal, since Windows
itself does not use this interface, and therefore no IP address is allocated. If the CX1020-N060 extension is
connected, the connection behaves like a 'normal' network port.
These interfaces are connected to an internal 3-port switch and offer a simple option for creating a line topology
without the need for additional Ethernet switches.