Setting Up: Device Ethernet And Tcp/Ip Notes - Beckhoff CU2508 Documentation

Commissioning
4.2.3

Setting up: Device Ethernet and TCP/IP notes

Table of contents
• Explanation of TCP/IP v4 [} 40]
• Application CU2508 [} 40]
• Settings for the dedicated TCP/IP port [} 41]
• EoE settings [} 41]
Explanation TCP/IP v4
TransmissionControlProtocol/InternetProtocol (TCP/IP) is the name given to a bundle of procedures from the
1970s, which defines a packet-mediated forwarding of data. This mediation procedure is used in
contemporary everyday communication, in particular on the Ethernet physics (e.g. Fast Ethernet, Gbit) and
the hardware-orientated MAC addressing normally used there. The basic principles of this set are
• packets of user data of 64 to 1486 bytes (special forms are not uncommon) are sent from a transmitter
to one (unicast) or more (multicast, broadcast) receivers.
• In IPv4 the source and destination addresses each consist of 4 bytes separated by a point, e.g.
"192.168.1.1" or "123.001.002.001".
Note: IPv6 extends the address space by a further 2 bytes and will replace IPv4 in the mid-term.
• There does not have to be a direct physical connection (cable) between transmitter and receiver;
instead, intelligent packet mediators analyze the source and destination addresses and forward the
packets (key words: routing and switching). This results in delays and possible loss of data.
• The IP is a bi-directional reconfirmed communication, because the receiver acknowledges the receipt
of data to the transmitter. This causes a further communication load and increased transport time. Lost
data can thus be repeated automatically.
• UDP (User Datagram Protocol) can also be used instead of IP. It works without reconfirmation, lost
data must then be requested again at a higher communication level. In return, less time is required for
data communication.
The Windows operating system manages TCP/IP communication with its Ethernet adapters in the so-called
NDIS network mediation layer. The adapter settings can be accessed via the Windows Control Panel-
>Network Settings or the Windows CE CXconfig tool from Beckhoff.
These circumstances make TCP/IP-supported communication unsuitable for an application with higher real-
time requirements, but very suitable for flexible (variable) connections via many hubs (intermediate stations)
with an arbitrarily high data traffic.
Application CU2508
Two methods are available if TCP/IP frames are to be transmitted via the CU2508 (with no real-time
requirement):
• one port of the CU2508 is defined as a dedicated TCP/IP port [} 41].
Hence, it works for the operating system as an "extension" of the port to which the CU2508 is
connected, with the MAC and IP data of the Gbit port used according to the operating system data.
Under TwinCAT with its integrated CU2508 driver, this port is then connected to the Windows NDIS
mediation layer in the Windows operating system. Real-time traffic is then no longer possible via this
port; the CU2508 works as a transparent frame transporter.
• the CU2508 is generally set to EoE operation [} 41] (Ethernet over EtherCAT), "via EoE".
Then the integrated virtual EoE switch is activated in the CU2508 system and the connection is
established to the EtherCAT systems connected to the CU2508. In the case of EoE, Ethernet frames
are transported within acyclic EtherCAT telegrams by mailbox procedures, fragmented if necessary in
the case of overlength. The EL6601 or EL6614 can be used as an EtherCAT/Ethernet interface.
The MAC and IP data of the Gbit port used according to operating system data are used for
addressing.
This procedure is usable only for connected EtherCAT circuits.
The setting is made in the Ports tab for the CU2508 and does not change the mode of operation of the
CU2508, but only the handling of TCP/IP Frames in the CU2508 driver.
40 Version: 2.6 Real-time Ethernet port multiplier