Machine-Mount I/O Go Everywhere

Technical Advances, Regulatory Reforms Allow I/O Components to Do the Same Jobs Outside of Their Former Enclosures

By Jim Montague

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Once you're willing and able to get out of your cabinet or other comfy shelter, you can travel anywhere to provide assistance—if you bring the right tools and protection. This is just as true for machine-mounted I/O devices.

"Builders want to get the costs out of their machines and produce them faster with the same people, and so they're learning they can assemble controls faster with machine-mount I/O," says Will Healy, marketing manager for networking products at Balluff ( Consequently, technical advances and regulatory reforms allow many popular I/O components governed by IP20 to take on their own IP67 protection, so they can do many of the same jobs outside their former enclosures.

"Customers are demanding higher IP ratings and simpler installation," says Helge Hornis, manager of the Intelligent Systems Group at Pepperl+Fuchs ( "Where IP65 used to be good and IP67 was great, many customers won't settle for IP65 any longer, and really want IP68/69K."

To achieve this machine-mount I/O simplicity, single- and two-piece designs are best, Hornis explains. "Fifteen years ago we designed I/O housings with bases that contained moving parts," he notes. "Now this same functionality is available in designs that are simpler, more rugged, and offer higher IP protection at lower cost. Installation time probably is reduced by a factor of five to 10."

Pepperl+Fuchs offers Connect & Done I/O modules, which are so small that most users don't even need to mount them in the usual way, Hornis adds. "Once connected to the network cable, they're simply dropped into the cable tray."

Meanwhile, Aaron Henry, marketing manager at Murrelektronik (, adds that more builders are exploring machine-mount I/O because they want to easily migrate from using only in-cabinet I/O to adding out-of-cabinet I/O. However, they want to do it using the same IP address on the same bus node, and this means using IP67-rated components. To give builders this capability, Murrelektronik introduced its Cube20/67 transition module about 18 months ago.

"We’ve always used a single-cable bus system that combines power and communications, and we launched our Cube67 I/O system for simple connectivity about nine years ago," Henry says. "Cube67 combines power and communications on the backplane, and can go from module to module to extend a machine’s I/O system, while our Cube20 is just for in-cabinet I/O."

IP20 and IP67 areas have recently started to blend, necessitating the Cube20/67 transition module, Henry says. "As a result, we’re seeing more acceptance of third-party I/O suppliers such as ourselves because builders and end users are really beginning to see efficient machine connectivity as a labor-saver when they’re laying out a machine," he says. "Not only can better connectivity reduce wire counts, but it also means less guarding is required and less protection of wire bundling is needed. Also, this kind of distributed I/O system makes maintenance and troubleshooting of machines easier because users don’t have to go into the cabinet as much and don’t need as much high-level expertise to do it. Problems are easier to find and switch out.”

Free of their cabinet-based straightjackets, machine-mount I/O devices have diversified, too. Adoption of I/O modules with sealed connectors has picked up speed for five or six years, and suppliers also provide more interface types and capabilities, such as functional safety, motion control and position feedback, reports Kurt Wadowick, I/O specialist at Beckhoff Automation (

"I/O density has increased from eight in a single width to 16 in a double width, and there are more types of I/O, such as those for encoder inputs, motor drives and I/O-Link for communications," Wadowick says. "To serve in more diverse applications, more machine-mount I/Os are sealed and IP67-rated against dust, oil and water, and extend their range to -13 to 140 °F for normal operations. We keep a close eye on our customers' applications, and adapt to help fill any gaps that appear, such as installing safety I/O components to detect a safe-stop condition about 200 ft up in windmills that are, by turns, colder, hotter, windier and harder to reach than other settings."

Charlie Norz, I/O product manager at Wago (, agrees that more potential users have been investigating out-of-cabinet I/O in the past two years, especially machine builders and process industry applications seeking to reduce terminations and wiring. "IP67 allows just one I/O block on the machine, so there's only one wire from it to the solenoid or RTD and only two terminations," he says. "Using a cabinet requires four terminations or more."

Machine-mount I/O blocks also are becoming more sophisticated and diverse, and so digital I/O points are being joined by data on electrical current, encoders, RTD modules and serial communications, Norz says. "This allows users to do a lot more tasks on the IP67 platform. In fact, our Speedway IP67 PLC can even do high-speed data processing at this device level, instead of the traditional approach of sending it back to a higher-level controller and waiting for a response."

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