The ubiquitous PC architectures, Ethernet and wireless networking are transforming industrial applications, helping integrators reduce costs. The industrial world is continuing to move to commercial-off-the-shelf technologies used in offices, but that push will always be tempered by the need for far more ruggedization.
Industrial consumers are adopting COTS products, but the hardware is often beefed up with sturdy housings, enhanced power supplies and other technologies that ensure that plant floor systems won’t suffer maladies like the blue screen of death. These extras add cost, forcing companies to closely balance their need for rugged equipment with the cost of additional hardware like extended temperature ICs and extended testing.
“If you’re using standard PCs versus industrial PCs, you’ll usually pay a factor of two or three to get the same amount of computing power in an industrial package. But if the reliability requirements are there, that extra cost will be money well spent,” says Dr. Gerd-Ulrich Spohr, innovation & technology strategy manager at Siemens AG Industry Automation Division.
Industrial suppliers have been migrating to PCs and other office-style components since the mid 1990s, a transition that is part of the shift to distributed computing systems. A growing number of the circuit boards inside manufacturing equipment use common PC components like Intel CPUs, but the packaging and equipment that surrounds these boards are significantly different.
“Servers for industrial usage usually have better power equipment and dustproof housing. The price of the equipment will depend on the type of housing, the power supplies and other upgraded components like chips with industrial temperature ranges,” Spohr says. Life cycle management will also help improve reliability, he added.
One aspect of this decision will be the manufacturing technique used in a facility. Companies in light industries may find it easier to use COTS components, as will some batch manufacturing operations. “If somebody has a batch process, they don’t need too much reliability on equipment because it often stops naturally,” Spohr says. While these natural shutdowns provide time to rest and check production lines, he noted that batch processes will suffer if lines shut down unexpectedly.
Regardless of the type of production lines being built or upgraded, economics will be a dominant factor when companies determine how much ruggedization they need. Hardened systems will typically have longer lifetimes in rough industrial environments, which often justifies the added expense for many companies. When management explores techniques that improve reliability, which includes ruggedized equipment and redundancy, they will have to trade off the cost of equipment and the impact that downtime will have on their productivity.
“Buyers have to decide ‘this is enough reliability for me at the price I want.’ In low level controllers like PLCs, there will be for a certain time the need for industrial-types equipment,” Spohr says. “There are already equipment manufacturers that are packaging standard CPUs in ruggedized boxes being sold as PLC replacements.”
The drive to COTS also includes both wired and wireless communication technologies. In both, economics are driving a shift to Ethernet and its wireless version, Wi-Fi. Their high volume pricing benefits are supported by technology – they give users high bandwidth and the ability to carry a number of protocols over one wire.
In the mainstream with wired technologies, some companies use routers provided by commercial suppliers like Cisco. “In communications, you’ll find a lot of components are more or less the same as in the office, though in industrial applications there are more hardened components so they can withstand the harsh environment,” Spohr says.
In wireless, the technology that’s being deployed by a growing number of industrial network managers isn’t exactly the commercial version of Wi-Fi, even though it’s based on the same IEEE 802.11 specification. That’s because demanding industrial users can’t accept interruptions that are acceptable for systems that carry e-mail and other less critical data.
“In industrial environments, there’s no way you can accept a loss of transmission,” Spohr says. That’s been addressed by adding some capabilities that account for the interruptions by opening up multiple data paths.
“Many times, that’s addressed by using transmitters and receivers that work on multiple frequencies,” Spohr says. If there’s an error on one frequency it goes over another so you don’t lose packets. “If you’re doing control over wireless, you have to use multiple frequencies.”
Though that sounds like a straightforward solution, upgrading Wi-Fi to provide the reliability needed in production facilities wasn’t an easy task. Ensuring that all packets are sent and seamlessly pulling the right packets from the different data streams has a number of possibilities for problems. Ironing out all the minute technical issues to insure that this complex technology works 100% of the time without any errors took some time.
“It took the industry about five years to enhance Wi-Fi and get an industrial version that would work in harsh environments,” Spohr says. “If you’re doing control, you have to use the enhanced methodology.”
While these multi-frequency wireless networks are optimal for many industrial environments, Wi-Fi isn’t the only solution. Mesh networks have the potential to give users lower prices and longer ranges, for example.
“There are some interesting options at the moment. ZigBee and some others are already established in laboratory areas. But there’s still R&D needed to take this technology to the industrial floor,” Spohr says.
He also notes that some factories may be able to use high end versions of Wi-Fi routers and gateways that are sold in electronics stores. That’s possible in environments that aren’t that much different than in front offices. For example, light industries with production equipment that doesn’t have high voltages could be candidates for lower-priced routers that aren’t ruggedized. However, the longer lifetimes and enhanced diagnostics offered by ruggedized equipment can make them equally attractive when full product life cycles are considered.
The pervasiveness of Ethernet highlights the benefits that can be gained when industrial users adopt COTS technologies. That trend is also transforming other aspects of the industrial world as PC architectures gain acceptance. In both areas, the decision to use commercial hardware must be tempered by the reliability requirements of manufacturing environments, which can be quite harsh. Figuring out how much upgrading each piece of equipment needs can be challenging, but the gains and savings can be equally rewarding.
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