Computer Solutions
4 Engineering professionals in disparate industries all need to integrate increasingly complex systems while at the same time ensuring reliability. Boris Sedacca asks engineers how to achieve this.
4 Tous les professionnels de l’ingénierie des industries disparates doivent intégrer des systèmes de plus en plus complexes tout en garantissant la fiabilité. Boris Sedacca demande aux ingénieurs comment y parvenir.
4 Engineering-Experten in verschiedenen Industriezweigen müssen alle zunehmend komplexe Systeme integrieren und zugleich deren Zuverlässigkeit sicherstellen. Boris Sedacca fragt Ingenieure, wie dies erreicht werden kann.
Automation networking demands resilience
I
ncreasing complexity in automated systems adds new points of failure. Engineers must ensure that individual component failure does not bring entire systems to a halt. There have been dramatic developments in supervisory
control and data acquisition (SCADA), fieldbus and resilient computing which have transformed the industrial landscape over the last couple of decades. HMI, PLC and servo technology have all been
affected by fixed and wireless communications. Fault-tolerant servers using dual- or multiple- redundant industrial networks need to be connected to plug and play hardware components, all controlled by resilient SCADA software systems. However engineers all have different views of the best way to achieve this. Cost is a particularly relevant factor. Michael Kohli, president of Kohltek, says: “I
had a customer who works for a major robotic manufacturer and when one of the engineers said he needed redundancy, my customer reminded him
they were not willing to pay for it. Apart from cost issues, hardware needs to be immune to interference and fade. It could mean using Spread Spectrum Hopping radios instead of Wi-Fi, RS-485 instead of RS-232, or fibre instead of wire.” Kohli contends that the proper use of
combining networks such as Rockwell’s Common Industrial Protocol (CIP) or using switches with Internet Group Management Protocol (IGMP) snooping to control traffic can ensure proper bandwidth allocation.
Sensor voting
“The easiest way to provide redundancy is through sensor voting, where three sensor are used and the two that agree win,” adds Kohli. “The use of 1+n redundancy is standard in most high reliability systems, but care needs to be taken to insure that repair can be made with taking the system down such as the use of hot swappable products.” Resilience in avionics software is as taxing
Fig. 1. Ever greater complexity in automated systems can add new points of failure. To overcome this, everything has to be tested at NASA.
Photo courtesy: NASA.
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