I/O on Demand: The New Paradigm

One of the Goals of Human-Centered Design Is to Eliminate Unnecessary Work

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Electronic Marshalling Streamlines Work

While I/O on Demand promises usability and labor-saving improvements for almost any choice of I/O approach, perhaps the most transformative innovation for project work is the practice of electronic marshalling.

For conventionally wired instrumentation, electronic marshalling allows users to land field cabling wherever there is an available terminal block in the marshalling cabinet—regardless of signal type or control strategy. Each terminal block is set up to receive a single-channel characterization module, or CHARM, which includes the A/D converter and associated signal characterization for that point's particular type of analog or digital I/O signal. Each I/O point is then digitally communicated via the marshalling cabinet's DeltaV backplane—and can be associated with any control strategy in any of the system's DeltaV controllers.

The effort and cost savings potential is enormous, because the manual cross-referencing of each incoming pair of wires with the appropriate I/O card is effectively eliminated—along with the requisite "spaghetti" wiring, extra terminal blocks and cabinet space. Further, because signal characterization is done on a single-channel basis, flexibility to accommodate late stage design changes is greatly enhanced. On a typical capital project, Emerson estimates that electronic marshalling could result in 32% reduction in DeltaV controllers, a 40% reduction in cabinet footprint, and a whopping 90% reduction in intra-cabinet wiring relative to conventional I/O practices.

Redundant Wireless Boosts Flexibility

A second important aspect of Emerson's I/O on Demand approach is the addition of redundancy to the company's Smart Wireless infrastructure offering. Redundancy will allow an increasing number of traditionally wired I/O points to go wireless—for incremental monitoring as well as for closed-loop control, Emerson believes. This will have a profound impact on the design of new facilities as well as the ability of brownfield plants to easily implement new measurement points and asset management strategies.

"44% of process control inputs can be wireless with no difficulty, and for a greenfield plant that's a savings of 7% overall," says Duncan Schleiss, Emerson vice president of platform strategy. "Getting rid of wires eliminates most activities associated with wiring design and installation," Schleiss adds. "Poof! Cabinets, wire, terminations, cable tray design, fusing, installation drawings and a host of other activities are simply gone."

Reducing Fieldbus Effort and Cost

Emerson's HCD effort also took a hard look at Foundation fieldbus and found that substantial improvements could be made in how fieldbus is done. "Foundation technology requires third-party power supplies and power conditioners—along with the necessary engineering and wiring and cabinet space," Schleiss explains. "And if you wanted to get at the bus diagnostics, you had to jump through OPC and RS485 hoops in order to get the information into the control system."

"With DeltaV S-series and I/O on Demand, we've integrated the power circuitry with the H1 card itself," Schleiss says. "Third-party power conditioners and dedicated power supplies—and the engineering that went with them—are a thing of the past."

Citing a recently completed project consisting of some 2,500 Foundation fieldbus segments, Emerson estimates that total project cost could have been reduced by some 7% using the new I/O on Demand approach. "Five thousand H1 power conditioners, 32 H1 power cabinets, along with their design and documentation, and all that factory and on-site wiring," lists Schleiss. "All gone!

"But we also integrated diagnostics. So now the maintenance staff can wait for the DeltaV H1 card to notify them of a problem on the physical layer, such as low voltage or high current. Easy! It's all integrated!"

Safety I/O Leverages HART Data

Emerson also has addressed flexible I/O considerations in the modular, distributed architecture of its safety instrumented system, DeltaV SIS. Fully configurable I/O for any type of signal, the ability to add incremental logic solvers at any time, and scaleability from 16 to 30,000 I/O points all contribute to increased flexibility, improved robustness and the elmination of single points of failure.

Further, the integration of DeltaV SIS with the DeltaV basic process control system (BPCS), allows users to leverage SIS I/O information to make better operations decisions.

Error-Proofing Conventional I/O

Even the DeltaV system's "conventional" I/O hardware has evolved to make life easier with the new S-series. Patent-pending heat dissipation technology allows for a completely enclosed shell (no vents). This prevents particles—or an errant screw—from entering a card and short-circuiting electronics.

And the new S-series hardware also offers "easy-on-hard-off" installation, which means there are no screws needed to install a card onto the backplane, yet releasing one requires pushing an out-of-the-way release button on top of the card.

In the final analysis, I/O on Demand spans both revolutionary new technologies as well as the sum-total of myriad human-centered design innovations—all in the name of shifting the I/O paradigm. Now, I/O doesn't seem quite so hard, does it?

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