Cover story
Maintaining long- life installed industrial communications networks
Support for legacy serial fieldbus protocols and industrial drives – by Ken Greenwood, Technical Sales Manager, Rochester Electronics
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uccessful industrial automation networks have always demanded the fastest, most reliable communication network to seamlessly link together all the elements of the factory system. Historically, industrial communications were created around a large number of customer-specific serial-based interfaces, which eventually became standards and protocols such as PROFIBUS, CANbus, Modbus and CC-Link. Whilst Ethernet-based solutions today (PROFINET, EtherCAT and EtherNet/IP) provide a common, faster and more cost-effective solution to industrial communications, installed serial-based networks continue to require long-term support, as do the older serial-based physical interfaces such as RS422/RS485/RS232. If it’s not broken, don’t fix it! Indeed, both the end customer and the equipment OEM might have reasons to maintain the status quo until performance benefits provide an overriding justification to upgrade the whole network. • If the current system provides the end customer with all the performance they need, any forced investment and re-qualification costs will be unwelcome.
• The incumbent equipment manufacturer risks opening a whole new tender process if the existing systems cannot be maintained. It seems counterintuitive, but there are significant reasons to avoid major system upgrades and to provide extended in-service support. Semiconductors are at the core of any industrial communications network. From the outlying sensor network through to the programmable logic controllers (PLC) and drive controls, semiconductors form the main
building blocks. Their ongoing availability is therefore key to being able to provide long-term system support. Unfortunately, semiconductor lifecycles continue to shrink. Semiconductor product discontinuations rose by 19% in 2020 driven by factors such as: • Acquisitions: Market consolidation continued at pace driving product rationalisation, or in some cases changing the dynamics of third-party fab arrangements.
• Wafer capacity for fabless semiconductor companies was squeezed as the increase in home networking and Internet connectivity consumed fab capacity. The investment and focus of the global wafer fab companies followed the market, and older technology nodes (45nm, 110nm) were discontinued.
Component discontinuations force customers to commit to a traditional last-time-buy where finished components are purchased at one time, to cover all future needs. As well as the tied-up capital in the stock itself, there are additional costs for specialised IC storage. Under perfect conditions, these costs are unwelcomed though manageable. Then, what happens if market needs increase, or in-service maintenance timescales need to be extended? It is a common misconception that after a component is discontinued by the original manufacturer, only the non-authorised network can help. Nothing could be further from the truth!
Sourcing through non-authorised routes, carries huge risks. Active component shortages (as in the current market), and the ongoing need for obsolete components provide additional “incentives” for gray market, poor quality or counterfeits to enter into the market.
Figure 1: Main functional blocks of an industrial system
06 October 2021
www.electronicsworld.co.uk
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