No Additives - makes Ethernet more attractive for industry

01 October 2007

Today, virtually all photoelectric sensors are readily available with various BUS formats. However, further product development will soon see these types of sensors featuring integration of the communication interface directly into the device with FAST Ethernet capability. Terry Boughen, managing director of Leuze Mayser Electronic, explains how this can offer direct benefits to the user.

Using Ethernet as a means of inter-connectivity between controllers and line devices within manufacturing and warehousing business sectors has been, in many areas, somewhat slow to take off. Some reservations may be linked to the operational capabilities of the line speeds or the increased installation requirements with gateways. However, today we are seeing much faster line speeds, moving away from the base level 10Mbit to Fast Ethernet (100Mbit) and Gigabit Ethernet (1000Mbit).
Ethernet uses the same frame structure, addressing scheme, and link access method (CSMA/CD). The big benefit of Ethernet networks is standards – network controllers all over the world use the same standards-based protocol, which allows for backwards compatibility, and enables some amazing capabilities, such as connectivity between separate sites.
It is not only the practicalities of the Ethernet speed that will attract interest for production and warehousing applications, some device manufacturers are starting to introduce components that incorporate Ethernet connectivity direct. This has a core advantage of reducing links and gateways compared with a traditional network configuration.

Handling industries, in particular the warehousing and packaging sectors, have been fortunate to be among the first to benefit with the introduction of measuring scanners and a new brand of bar code readers launched this year.

Ethernet technology has suffered for years from a perception that in an industrial setting the required communication speeds were not there. This is no longer the case.

As a hardware technology, Ethernet addresses nearly all the requirements of the specialised industrial buses, with the added advantages of widespread usage and lower costs due to high volumes. As industrial networks gain in popularity, Ethernet will be used more and more as a solution for high-speed communication backbone applications between PCs or workstations and the industrial network.

However, some networks require specialised fieldbus networks. These will be used at the device level and a 'gateway' converter will connect these special sub-networks into the larger Ethernet network. Having a single network technology from the enterprise to the sensor level gateway will greatly simplify systems architecture, design, installation, and maintenance.

However, there are still challenges.

For the most part, components are designed for use in office environments and some people are concerned about industrial applications. However, the growing use of Ethernet in industrial applications has created a market for industrial components.

Ethernet technology is based on collision detection and avoidance that slows down the response of the network as traffic increases. To avoid this becoming an issue a network has to be planned. Traffic must be kept below its theoretical limits and, using switching technology, a network can be split into smaller ‘domains’ or groups of devices. This reduces the overall site-wide data flow and the chance of unwanted data collisions. Most Ethernet installations today are based on 10 Mb/s or 100 Mb/s Ethernet technology. However, faster Ethernet networks based on the newer 1000 Mb/s (equals 1Gb/s), are quickly becoming the de-facto standard in new installations.

There will still be a role for specialised industrial buses, and standard bridges will allow users to connect these buses into the Ethernet network. However, the new generation of devices being introduced, such as the 500i series of bar code readers with integrated Ethernet capability, will streamline systems connectivity with superior results. Users will see a large degree of interoperability thanks to standards based control layers such as TCO/IP and EIP.

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