Spare parts will not be available and repairs not be possible for the S5 family of products, Siemens reports.
S5’s main achievement was that it offered factory engineers a significant increase in computing power; as well, control functions enabling higher-level tasks to be performed.
For many engineers, the end of S5’s lifecycle has prompted a sense of nostalgia. This includes Alan Norbury, now chief technology officer, who was working as an apprentice in Congleton when the S5 was being launched.
In the following years he was one of three product specialists out on the road winning the hearts and minds of production managers and encouraging them to take a technological leap of faith.
“In the late 1970s, engineers were used to wiring diagrams and relay panels,” Norbury said. “The arrival of S5 - which was a tenth of the size of your traditional hard-wired panel - was a huge advance. “Siemens were very aware of the cultural change it was proposing, so designed S5 to look familiar to a 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 psychological change. A move from the physical to software required a new mindset of what was now possible and an entire set of new skills.
“It was a new world to engineers, so the challenge was getting customers to understand the value of change. We gradually overcame those barriers.”
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 operation 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.
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 groundbreaking,” Norbury explained. “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 find a fault. This was a huge benefit to customers in the automotive industry. It sped up fault diagnosis and increased the uptime of machines, which saved them a lot of money.”
Later, Siemens launched its universally applicable S5 U series, and sales figures grew rapidly. The advent of the S5-100U range, which introduced a central processing unit (CPU) option, reduced switching times and enabled more complex and faster production processes.
Dave Pickles, managing director of Capula, an industrial systems integrator, started his career at Siemens as an apprentice engineer with Norbury and was involved in training electricians to use S5.
He says: "It is remarkable that decades later I am still opening cabinets in plants and finding S5 beavering away, given the advances we have made in automation. I suspect I’ll still be finding units that have been forgotten about in years to come.”
For 16 years S5 made progressive strides, paving the way for its replacement, the first generation SIMATIC S7 in 1994. Its arrival heralded the beginning of the network era and another leap forward for automation, offering more power, speed, flexibility, open communications and architecture, and faster more intuitive diagnostics.
As to what the future will bring, Norbury believes the next stage for automation is artificial intelligence controlling production robots that solve new tasks autonomously and factories that continuously optimise themselves. “When I look back to the start of my career focused on relays, contactors and push buttons, through automation and into software and virtualisation, I couldn't have imagined that we would be where we are today.”