Electricity + Control December 2020

TRANSFORMERS, SUBSTATIONS + CABLES

Use existing cabling to create a new industrial LAN You wouldn’t build a new railway or motorway every time you needed to travel somewhere, so why install new cable?You probably already have spare cores in your existing multi-core cable network or, better yet, an old telephone network that’s lying unused. Gary Bradshaw, Director at network specialist Omniflex, explains how the company’s Conet technology allows businesses to repurpose existing cabling to create a new industrial local area network (LAN).

Gary Bradshaw, Director at Omniflex.

T oken passing, peer-to-peer network? Check. High system redundancy? Check. Ten-kilometre transmission distance? Check. Data integrity and security? Check. Low latency? Check. These aren’t features you would typically think of when you repurpose existing infrastructure to create a new, high-performance industrial network. And it’s usually more profitable for most suppliers to sell you a new network. But there’s another way of looking at it. In an age where we need to consider the circular economy, when we must consider costs and reduce wasted resources, it’s about elegant engineering. It’s about using what you already have to deliver performance that’s equal to, or better than, a bespoke new system. This is exactly what we’ve done at Omniflex with Conet, a true token-passing peer-to-peer LAN. Conet was developed and launched in 1981 in response to a need from plant operators who wanted to bring field data back to the control room or supervisor’s office in the most cost- effective way. The only solutions that existed at the time were expensive and beyond the reach of smaller operators. This is why

one of the most important features of Conet is its ability to operate on low cost cabling which, in many instances, is already available as a free pair in an existing multi-core or telephone cable. This type of network design was inspired by the requirements of the mining industry where the nature of the job means a reliable network is needed to run from the surface to the underground levels in the mine, often with power cables. These are applications where wireless networking is simply not possible, or is too unreliable given the mission-critical nature of the operations. This is also the case for nuclear sites, where new cable installation, soil excavation and building work must adhere to strict construction rules specific to the nuclear industry. On these sites especially, it’s not only cheaper but also operationally beneficial to make use of the existing cable infrastructure on site. Key benefits Conet offers two key benefits: multidrop telemetry and data acquisition. The first means Conet can be used to transmit digital and analogue signals from one or many nodes with- out a central host computer. The second means multiple host computers can connect to the network to communi- cate with field devices such as PLCs (programmable logic controllers), RTUs (remote terminal units) and other digital devices. As well as this capability, at its heart Conet is still based on the ISO OSI 7-layer model, so it meets networking standards theworld over. It is on this foundation that Omniflex engineers have built high-performance features that make Conet a resilient technology. These include a robust token- passing protocol, allowing users to add or remove up to 127 nodes on the network without reprogramming the system. It is also a deterministic network, making it ideal for real-time applications where low data-loss rates and low jitter are required. Here, the throughput and access times are recorded between 0 and 100 milliseconds. The system also offers high data integrity and electrical noise suppression; each node is transformer isolated to block voltage fluctuations.

Conet was developed to offer plant operators a way of bringing field data back to the control room or supervisor’s office cost- effectively.

26 Electricity + Control DECEMBER 2020