Machine-Mount I/O for Harsh Environments

March 20, 2015
Reducing the distance between I/O devices and the signals being monitored can eliminate the cost, inconvenience and possible error sources associated with long wire runs.

New technologies and the inclusion of existing technologies are helping to make machine-mount I/O an alternative to cabinets, and these devices often can be used in harsh environments.

Machine-mount I/O can be advantageous and cost-effective in certain circumstances. For those planning to increase automation, it may be worth looking into.

“Depending on equipment type, cabinet-free automation systems help in minimizing the planning, cost, start-up and servicing of automation applications,” says Charlie Norz, I/O-System product manager at Wago.

Reducing the distance between I/O devices and the signals being monitored can be very beneficial, eliminating the cost, inconvenience and possible error sources associated with long wire runs, says Earle Foster, senior vice president of marketing at Sealevel Systems.

Machine-mount devices eliminate other wire issues, such as stripping and terminating wires, testing and debugging, while enabling the ability to add more I/O points for the future without having to modify the cabinet, says Shishire Rege, marketing manager, networking and connectivity, at Balluff. This makes it easier to adapt to changing customer demands. Rege says that, while engineering changes are required to define which port to use when plugging cables in the I/O block, it takes only a few minutes instead of hours to implement, reducing downtime and shortening build time.

Also Read: Machine-Mount I/O Go Everywhere

Among the technologies leading the way in this shift are various communications protocols and their price points.

“Fieldbuses can now provide communication between control unit, system and machine, thereby eliminating the need for discrete wiring,” says Norz.

Further helping to reduce wiring is IO-Link vendor-neutral technology, which enables I/O blocks to multiply the I/O points several times over. “IO-Link ports on the machine-mounted I/O opens entirely new possibilities to easily connect smart sensors, also called measurement sensors,” says Rege. This will reduce sensor wiring down to a single standard M12 cable.

In addition to fieldbuses and IO-Link, stand-alone I/O adapters are available that use Ethernet or USB to interface to the host computer, and modules are made that are suitable for the factory environment, adds Foster.

Product cost reductions also are helping to fuel the machine-mount I/O market. These reductions are achieved through the acceptance and expansion of Ethernet into the industrial market.

“This acceptance is reducing the cost of the Ethernet components integrated into machine-mount I/O,” says Jason Haldeman, product marketing lead specialist—I/O and Light, I/O and Networks, for Phoenix Contact USA. “In the past, product costs were the biggest hurdle to overcome. It was hard for people to see past this initial cost and see the overall cost savings down the road in labor or installation time. With labor cost on the rise and component cost down, machine-mount I/O looks a lot more attractive to the I/O market.”

Also useful for machine-mount I/O is inductive coupling to transfer power and data over an air gap. “Inductive couplers can be used on robot end-effectors, tool changers, indexing or turntables and in automotive assembly automation to supply power and data to the assembly on pallets,” adds Rege. Without mating connectors or friction, there is no wear or tear.

It’s not as much the introduction of new technology, as much as the proliferation of proven technology to include a wider range of products,” says Todd Bissell, commercial program manager for sensing, safety and connectivity, Rockwell Automation. “The sealing and connection techniques found on the devices that have been out on the machine for ages—sensors, switches, connection components and I/O—are being added to controllers, motor control, safety products and even network switches,” he says.

Factors that once were prohibitive for using machine-mount devices in harsh environments are being addressed.

“Environmental factors such as heat, humidity and spray are key when it comes to designing a panel or machine,” says Andrew Barco, product manager—network connectivity, Weidmuller North America, who believes that machine-mount devices allow designers more flexibility while meeting harsh environment ratings. “These factors pose limitations on where the machines can be placed, and accommodating them can often add to the cost of the machine. With that said, the adoption of technology has recently started to catch up with designers’ imaginations.”

Constructing the housings with more robust materials also is paving the way for harsh-environment use. “Stainless steel, die-cast zinc and IP67-rated plastic are a few of the main options available from vendors,” says Kurt Wadowick, I/O systems specialist at Beckhoff Automation. “Stainless steel is ideal for the demanding cleaning procedures common to food and beverage, packaging and pharmaceutical machinery. Die-cast zinc I/O boxes offer increased load resistance and protection against weld spatter. Rugged IP67-rated plastic offers moisture and dust resistance and is the more commonly used option by machine builders who utilize machine-mountable I/O.”

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