Fieldbus vs Ethernet

It’s a popular debate amongst engineers and facilities managers nationwide: should you opt for a fieldbus protocol or an Ethernet protocol to connect your industrial components? PIF reviews the merits of both technologies, and explains why – whichever option you settle for – you should always choose Murrelektronik products.

How fieldbus works

Fieldbus allow up to 32 fieldbus devices to be wired using a single ‘trunk’ or ‘segment’ cable and each instrument connects to the cable as a ‘drop’ (instruments must have a fieldbus interface and relevant software to provide the fieldbus communications). A fieldbus trunk or segment – either FOUNDATION fieldbus H1 or PROFIBUS PA – is a single twisted pair wire carrying a digital signal and DC power. Most devices are two-wire bus-powered units requiring 10 to 20mA. However, it is also possible to have 4-wire fieldbus devices in the case of devices with a high current draw.

Ethernet explained

Industrial Ethernet protocols, such as PROFINET and Ethernet/IP, use standard Ethernet to ensure specific manufacturing data in Real-time. Time Accuracy will be about 1ms. This is perfect for conveyors, powertrain or bodyshop in automotive plants. Standard ethernet hardware can be used.. .

Industrial Ethernet protocols, such as Ether-CAT, PROFINET IRT modify standard Ethernet to ensure specific manufacturing data is sent and received on-time – exactly when the data is needed to perform specific operations. For example, a bottle-filling plant that employs Industrial Ethernet automation technology can send filling data over the network to ensure the bottles are being filled properly. So, when a bottle is full, a ‘stop filling’ command is sent over the network, providing essential Real Time Automation reporting. Time Accuracy will be in micro seconds.

Which protocol is more popular?

The majority of industrial components have historically been connected through serial fieldbus protocols, such as PROFIBUS, Control Area Network (CAN), Modbus and CC-Link. PROFIBUS is the world’s most successful fieldbus technology and is widely deployed in industrial automation systems. In recent years, industrial Ethernet has gained ground, offering higher speed, increased connection distance and the ability to connect more nodes. The most popular Ethernet protocols include PROFINET, PROFINET IRT, Ether-CAT, EtherNet/IP, Sercos III and CC-Link.

Which protocol should you favour?

Ethernet is becoming more cost-effective (a common criticism), with common physical links. Standard Ethernet protocols achieves very low latency and enable a flexible network topology. As such, many industrial communication protocols are moving to Ethernet-based solutions. However, whilst industrial Ethernet networks are growing in popularity, when it comes to connecting field-level equipment to control systems, device and fieldbus networks are still the simplest and cheapest way to go.
Deterministic Ethernet Protocols as PROFINET IRT, Ether-CAT are established on the market and available in the Murrelektronik fieldbus portfolio.

Choose Murrelektronik for all your Ethernet and fieldbus needs

Murrelektronik’s latest TREE67 range can be selected with either four or eight M12 Ethernet ports. These switches make it possible to implement decentralised machine concepts, increasing communication speed across a network. Murrelektronik also offers the widest range of Industrial Ethernet connectors on the market. No matter if they’re used in IP20 cabinet wiring or in a harsh industrial IP67 environment – Murrelektronik has the ideal Ethernet connector for you.

Plus, as experts in fieldbus architecture, Murrelektronik can provide a range of fieldbus systems. Cube67 is their award-winning, modular fieldbus system that can communicate over most industrial communication protocols. The IP67 rated MVK Metal compact fieldbus has been designed for harsh environments. Or their MVP12 Steel distribution box, made of high-quality stainless steel, is the perfect solution for a decentralised approach in Food and Beverage machines and installations.

So, there you have it. The decision to stick with fieldbus or twist for Ethernet still largely depends on your budget. Thankfully, Murrelektronik has got you covered. No matter what your budgetary requirements, and whether you ultimately favour fieldbus or Ethernet, Murrelektronik has the technology to keep you connected.

For more information about the complete range of Murrelektronik fieldbus and ethernet products, speak to one of their experienced advisers today by calling +44 (0)161 72831-33 or email sales@murrelektronik.co.uk.

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