Infrastructure components

The router

Industrial access routers provide a simple and secure connection between office networks, or between the Internet and production networks.

Routers purposefully separate different networks. Access to the production network behind the router is only allowed for author-ized users. This allows a connected facility to be concealed be-hind a single IP address. Thus the installation overhead is signifi-cantly reduced.

Thanks to the integrated modem (analogue or ISDN), the router can be accessed from any point around the globe via the tele-phone network for configuration, administration and monitoring purposes. A VPN (virtual private network) connection can be used to connect two routers through a local Internet service pro-vider. Only authorized applications are then allowed through.

Application areas:

• Separation of Ethernet networks

• Opening access to the Internet

Ethernet networks should be separated with a router. This simplifies the data exchange and reduces the risk of long response times.

Various options, such as VLAN or QoS, are available for isolating and prioritizing network data. A router filters data at the IP level.

Only authorized users can access the secured network remotely.

And only approved devices can send data out of the secured net-work.

The router uses a single IP address to conceal a machine with its own IP subnet and multiple network nodes. External access at-tempts to this IP address are automatically forwarded to a prede-fined IP address on the network behind the router. If required, the device can be kept isolated from the outside.

Wave-LINE SWITCH/ Industrial Ethernet switches A switch is a network component used for connecting multiple nodes with a local network.

Tasks:

• Structuring networks

• Optimizing communication paths and times for data traffic

• Increasing the data throughput Features:

• Very sturdy and reliable

• Assembly on top-hat rail or wall

Industrial networks with industrial Ethernet require high-perfor-mance managed switches. These switches serve as centralized intermediary units within the electrical cabinet. There are signifi-cant differences between them and unmanaged switches.

Overlapping functions and operational modes Auto-crossing:

• Automatic detection and correction of the transmit and receive data lines.

• This allows components to be connected using both 1:1 straight-through wired cables and also cross-wired cables Auto-negotiation:

• The data transmission rate is automatically and independently negotiated with the link partner at each port

• The link is created utilizing the highest-possible rate of data transmission at which both partners are capable of communi-cating

Blocking:

• Non-blocking – when the switch capacity is sufficient to deal with connection to all partners at the maximum data rate

• Blocking – when a connection cannot be established because of a capacity overload

Half-duplex:

• An operational mode where the Ethernet node is either send-ing or receivsend-ing data at any point in time

Full-duplex:

• An operational mode where both partners can communicate at the same time bi-directionally

Managed switches

A configuration of the managed switch is always required be-cause of its wide array of configurable functions. A terminal pro-gram or Web interface can be used to propro-gram the switch. This simplifies the process of adjusting components and allows the operator to use almost any connected PC to configure remote, far-off devices over the network.

The implementation of a monitoring function for individual ports makes it easier to troubleshoot after a malfunction.

Application:

• Port trunking

• Port mirroring

• VLAN

• IGMP snooping

• DHCP

• RapidRing

Unmanaged switches

Unmanaged switches enable an entry into the world of industrial Ethernet. You do not need to make any configuration; rather con-figuration is accomplished by Plug-and-Play.

Application characteristics:

• For price-sensitive applications

• Designed as compact, Plug-and-Play modules

• Enables simple installation of industrial Ethernet networks

• Configuration or parameter assignments are not required

It is important to realize when using unmanaged switches in Ethernet/IP networks with real-time I/O traffic that the multicast broadcasts for certain address ranges are sent out unfiltered to all ports (as a broadcast). This results in an increased network load.

Wireless LAN (WLAN)

Wireless LANs are local networks not bound by physical hard-wired connections. An access point is needed to take advantage of the wireless technology. The access point serves as a gateway between the cable network and the wireless network.

Operator front-end PLC access point

Wireless

WLAN miniRouter

Managed Switch

Security features:

• The current encryption standards are WPA and WPA2

• A MAC address filter only allows authorized network devices access to the wireless network

The implementation of a WLAN in a corporate setting must be thoroughly planned and designed with the most stringent security measures possible.

a) Application areas

• Mobile connection for laptops

• For vehicles or machines that need to collect data in ware-houses

• In the automation sector

• For recording measurements or for machine control b) Frequencies

Two license-free frequency ranges are available for wireless net-work communications:

Standard Frequencies Channels 802.11a 5.15 GHz -

5.725 GHz

Channels: 19, all with no overlap, in Europe with TPC and DFS, according to 802.11h 802.11b/g 2.4 GHz -

2.4835 GHz

Channels: 11 in the USA / 13 in Europe / 14 in Japan. Maximum 3 channels with no overlap For all standards, the channel bandwidth is between 10 and 30 MHz.

c) Channels

The most widespread standard is 802.11b/g. It has a frequency range of 2.4 GHz to 2.4835 GHz. The frequency ranges are dis-tributed among the individual channels as follows:

Channel Frequency Application countries 1 2.412 GHz Europe, USA, Japan

d) Range of coverage

• The permitted level of emissions for standard WLAN devices is 100 mW.

• Typical coverage ranges from 30 m to 25 km depending upon the hardware and the application.

• The coverage range is dependent on physical obstacles as well as the type and material of the surrounding buildings.

• Metallic infrastructures and stone or concrete walls cannot be easily penetrated and increase attenuation.

e) Data rates

Make sure that all network nodes share the uploading and downloading bandwidth. Furthermore, the data rates provided are only theoretical values and are based on optimal conditions. Ac-tual data rates achieved will be considerably lower than the theo-retical values.

IEEE-/Group Description

802.11 WLAN for 1-2 Mbit/s on the 2.4-GHz band 802.11a WLAN for 54 Mbit/s on the 5-GHz band 802.11b Expansion of 802.11 up to 11 Mbit/s on the

2.4-GHz band

802.11g Higher data rate (from 20 Mbit/s) on the 2.4-GHz band

f) QoS

IEEE 802.11e is an industrial standard in the IEEE 802.11 wire-less LAN standard. It supports the quality-of-service concept.

Data packets are assigned a priority depending on the sender.

An access point recognizes the priority of the data packets and gives preferential treatment to packets of higher priority. Real-time applications can be better supported with help from IEEE 802.11e. IEEE 802.11 establishes a defined bandwidth on the network which ensures that data packets arrive at the receiver within a defined time interval.

g) Interference

Different types of interference can occur with other radio trans-mission systems, since WLAN uses the same license-free fre-quency blocks as other applications (such as Bluetooth technol-ogy).

Media converter

A media converter connects copper cable with fibre-optic cable.

Pump station 20 km

Transparent link

Media converter Media converter

Copper conductors are adequate for the majority of ap-plications. However fibre-optic cable is required for spe-cial applications:

• Line length is greater than 100 meters

• Electromagnetic interference

• No equipotential bonding

ComServer

A ComServer can be used to connect a device with a serial inter-face to the network. This allows you to easily connect an existing RS232-interface production facility into your Ethernet network. All computers integrated into the network can access the interface.

CU

CU

CU

Operator front-end Production facility

CU

RS232

GPRS-I/O alarm module

The GPRS-I/O alarm module is designed for collecting messages which originate in decentralized industrial facilities and building installations.

Functions:

• Alarm messages via SMS, fax or e-mail

• Fully configurable messaging chain with eight target num-bers per input

• Wireless, transparent data transmission to a serial inter-face on the machine or facility

• Additional alarm service functions via GSM, in order to also provide messages in event of malfunctions in the GPRS dedi-cated line

• Remote maintenance and configuration is accomplished over the analogue modem connection

• Values from a machine or system can be regularly stored to a data logger (server) on the Internet. Values can also be simul-taneously retrieved from the data logger.

• Continuously online due to the GPRS connection

• Can be controlled remotely with remote switching of the out-puts by means of telephone, mobile phone and SMS mes-sages

• Minimal cost of acquisition and inexpensive operation

Industrial power supply units

The Weidmüller Power Supply Unit is an ideal partner for our complete range of Ethernet Switches and Communications Electronic devices.

2.13 Passive components for copper cabling

In document Industrial Ethernet Handbook (Page 39-52)