FEATURE PLCsy


End of the road for Simatic S5


Siemens Simatic-S5 (right), the iconic workhorse of automation, is being put out to pasture


S


ince its launch over 40 years ago, the ground-breaking programmable logic controller (PLC) has automated countless


machines and processes, and transformed production in every industry imaginable. The Siemens PLC – the Simatic S5 –


off ered factory engineers a signifi cant increase in computing power. Add to that control functions enabling higher-level tasks to be performed and its robust and simple technical layout, it is no wonder so many are still in use today, including at small manufacturers and giants alike, such as Heinz at its plant in Wigan.


End of an era


Now the Simatic-S5 has been retired. Its product life-cycle ended on September 30th, which means spare parts will not be available and repairs not possible for the this family of products, heralding the end of an era and a move to next-generation Siemens technologies.


For many engineers, the end of S5’s lifecycle has prompted a sense of nostalgia and refl ection about the impact and legacy of this game-changing box of tricks. This includes Alan Norbury, Chief Technology Offi cer at Siemens, who was taking his fi rst


steps in his illustrious career as a Siemens apprentice in Congleton, the same moment as S5 was unveiled to the world. But, it wasn’t a straightforward journey


from PLC newcomer to market leader, as Norbury can attest to. In those early years he was one of three product specialists out on the road, encouraging production managers to take a technological leap of faith.


“In the late 1970s, engineers were used to wiring diagrams and relay panels. The arrival of S5 – which was a tenth of the size of the traditional hard-wired panel – was a huge advance,” said Norbury. “Siemens was very aware of the cultural change it was proposing, so designed S5 to look familiar to what relay-panel engineers were used to. But, the biggest shift was that the functionality was ruled by a stored program rather than a hard-wired system. That was the biggest barrier: the change in approach. A move from the physical to software required a new mind-set of what was now possible, and an entire set of new skills.”


It was certainly a new world to engineers, so the challenge was getting customers to


understand the value of change. “We gradually overcame those barriers,” said Norbury.


The S5 line The S5 line was produced in 90U, 95U, 101U/R, 100U, 105R, 110A/S/F 130A/W, 150S 115U/F/H, 135U and 155U/H chassis styles. The higher the number, the more sophisticated the system. For each chassis, several CPUs were available, with varying speed, memory and capabilities. Some systems provided redundant CPU support for ultra-high-reliability control, as used in pharmaceutical manufacturing. Others provided failsafe capabilities, designed to safeguard machines and people, used in applications such as oil and gas, for example.


Much of the success of S5 is owed to the


introduction of the engineering software Step 5, which made it easier to quickly create and modify programs. “It was ground-breaking: Structured


programming was a big leap for engineers working in automated plants, and enabled them to diagnose faults much more quickly. It was easy to follow and you could label elements to organise the software. There was no longer a huge linear string of code to wade through to fi nd a fault,” said Norbury. “This was a huge benefi t to customers in the automotive industry. It sped up fault diagnosis and increased the uptime of machines, which saved them a lot of money.”


Siemens apprentices, 1978 8 November 2020 | Automation Simatic S5, 1983


It wasn’t long until S5 was the leading PLC in the market, but competition and industry needs were driving forward advances in automation technology. For Siemens that meant setting itself apart


automationmagazine.co.uk


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