Distributed Digital I/O Solves Problems

It's Hard to Overlook the Benefits When You Move Away From Hardwired Control Systems

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Some machines still use hardwired I/O components and run points back in cable trays to motor control centers and PLC combinations. This approach has advocates vs. on-machine components with instruments wired via a digital protocol.

"The advantages are cost saving and being able to distribute, so you have redundancy," says Eric Rice, director of technical support for North America, Intelligrated (www.intelligrated.com) in Cincinnati. "If one of the main cables is cut, there's no downtime. If someone with a fork truck severs wires in a centralized control scheme, then the entire system is down."

Local racks provide a one-stop location for troubleshooting vs. having to open junction boxes and cabinets that aren't always mounted in an easily accessible spot, says Wade Peterson, electrical engineer, CMD (www.cmd-corp.com) in Appleton, Wisconsin. "However," he cautions, "local racks have significant problems when they outgrow their original cabinets. These same issues are trivial with distributed I/O. It's easy to add a new junction box with 10 blocks of I/O and a new node on the network."

Because of the in-depth analysis and diagnostics value of data in a distributed I/O structure, the whole push toward green technology is on the horizon, says Jim Braun, vice president of product development and standardization for MAG Americas (www.mag-ias.com) in Hebron, Kentucky. "If you look at the machine tool industry as a big consumer of electricity, most people want to make parts faster, and that consumes more power," he explains. "In the future, we envision ways of being able to monitor that power and potentially give guidance to the customer about what he might want to do from an energy conservation point of view."

Digital I/O 

Fuse the Circuit
WTB2-FB130L IEC fuse holder terminal blocks have a current rating up to 30 A, and accept ¼ x 1¼ in. fuses. They have a built-in LED circuit to indicate when the fuse blows and funneled wiring entry with finger-safe IP20 terminals. Marking system allows for fast and easy circuit identification.

 Digital I/O

Push It
Modular push-in terminal (PIT) blocks reduce insertion forces compared with other spring-technology products. With a 2.5 mm2 cross section, an orange actuation button opens the spring to maximum wiring space of 14 AWG, and the devices are compatible with standardized push-in bridging, marking and testing accessories for all connection technologies.
Phoenix Contact

 Digital I/O

Four R Series I/O modules for the PXI platform are equipped with Xilinx Virtex-5 field programmable gate arrays (FPGAs). PXI-7841R, PXI-7842R, PXI-7851R and PXI-7852R modules have eight analog inputs, eight analog outputs and 96 digital I/O lines, as well as analog input rates more than 3.5 times faster than previously released R Series devices. These modules provide engineers with commercial off-the-shelf hardware that can be graphically programmed with the LabView FPGA module to perform custom onboard processing for in-line data analysis and deterministic I/O control for applications that require specialized timing and triggering.
National Instruments

 Digital I/O

Decentralize the I/O
With IP67 protection, X67 I/O modules can be installed on the machine, and can span 100 m between modules. Users can set parameters for the digital inputs and outputs and connect to all standard fieldbuses.
B&R Industrial Automation

 Digital I/O

Motion I/O
Universal I/O module for multi-axis RMC150 motion controllers has two analog inputs, six discrete I/O and two high-speed Quadrature/SSI channels. The 16-bit analog inputs can be used for pressure/force control or as position or velocity reference inputs. Quadrature/SSI channels can be configured as ½-axis quadrature or SSI reference inputs for gearing or to synchronize multiple controllers.
Delta Computer Systems

 Digital I/O

Module Finds Trouble
With KE-style enclosure-mount, four input/four output, AS-Interface I/O modules, should an output wire be disconnected, switchable lead breakage detection automatically sends the peripheral fault signal to the upper level controller. Any input pulse/noise spike less than 2 ms is automatically filtered out by input pulse suppression. Advanced diagnostic LEDs alert the user to reverse polarity, overload or short circuit conditions.

 Digital I/O

Modbus Supporter

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