I/O today, I/O tomorrow

Based on the results of a recent survey, this article takes a look at how users implement I/O today, what they like, dislike, and expect to happen with the systems they’ll use tomorrow.

By Jim Taylor, VDC, and Joe Feeley, Editor in Chief

As we’ve done in previous years, we invited Industrial Networking readers to participate in a study conducted by Venture Development Corp. to get good overview of user requirements for distributed/remote I/O.

The results summarized here are a compilation of the responses made by end users, industrial OEMs, and system integrators during interviews with VDC analysts and via a web-based questionnaire.
 It’s a big market. Worldwide shipments of distributed/remote I/O for industrial markets totaled $3.2 billion (US) in 2005 and are forecast to approach $ 4.3 billion in 2010 (5.9% CAGR).

The growing acceptance of distributed/remote I/O as a means of reducing costs associated with the hard wiring of devices to local I/O at controllers provides the major growth impetus. More than half of the overall 2005 shipments were for OEM and SI applications, but, not surprisingly, end users represented 65% of the DCS use. 

The applications profile isn’t seen to change markedly during that time. The segmentation of markets by product classes today stands at 54% to PLC-centric applications, 34% to DCSs, and 12% to PC-based control systems. By 2010, the study estimates those shares to be 55%, 33%, and 13% respectively.

The market for distributed/remote I/O for PC-based control systems is much smaller than the market for the other product types under study, but should achieve the highest growth rate (6.4%) through 2010. However, the study suggests that the hype surrounding PC-based control systems has died down somewhat and the future displacement rates are not expected to be as pronounced. One reason given is the increasing intelligence provided in PLCs, as well as displacement of DCSs by PLC systems.

There is some trend toward greater implementation of distributed/remote I/O by industrial OEMs and system integrators that the study suggests reflects the outsourcing of new controls designs and retrofits by end users, as they look to cut back on engineering staff and concentrate on their core operations. In addition, with the increasing sophistication of controls, many end-user engineering and implementation staffs lack the needed expertise they once had. 

For DCS applications in the end-user segment, the largest markets are the electric power, chemical, and petroleum & gas industries. The fastest growth forecast is for applications in the petroleum & gas industry. The largest OEM and system integrator markets involved with DCSs are in process controls for the electric power and chemical industries. The fastest growth forecast is for use in controls for textile manufacturing equipment/machinery.

PC-based control system applications in the end–user segment revealed the largest markets are automotive and electric-power industries. The fastest growth forecast is for applications in the plastics industry. The largest OEM and system integrator markets dealing with PCs are in controls for material handling and packaging equipment/machinery. The fastest growth forecast is for use in controls for textile manufacturing equipment/machinery.

PLC system applications in the end-user segment reveal the largest markets are the automotive and food & beverage industries. The fastest market growth forecast is for applications in the consumer products industry.

The largest OEM and system integrator markets for PLCs are in controls for assembly, packaging and material handling equipment/machinery. The fastest growth forecast is in process control applications for the petroleum & gas industry.

Let’s Get to the Users
The study asked the participants to identify the most important product features, characteristics, and specs that they consider when selecting distributed/remote I/O. Whether in PLC, DCS, or PC-based applications the top three considerations were compatibility with existing or other systems, compatibility with chosen hardware, and reliability, although not in the same order, and with less mention (as a %) by the PC-based group. Figure 1 details the major findings.

Participants were asked for their recommendations on how to simplify, reduce, and speed up maintenance of these I/O products. Self-diagnostic capabilities and easier-to-use diagnostics were the clear top choices, mentioned by more than 60% of the respondents. Better documentation and better vendor web site support can third and fourth.

Hot-swappable I/O was named an important consideration for the DCS crowd—64% called it very important. By comparison, 52% of the PLC group and 28% of the PC-centric users called it very important. All users did recognize the importance of hot-swapping for applications in which high levels of uptime and reliability are vital. 

The study also asked about the most important non-product-performance criteria in making a selection. Price (named by 54%), application/technical assistance (51%), customer support (40%), and parts availability/delivery (39%) were top of the list. Figure 2 identifies the other criteria mentioned.

The Ins and the Outs
The study participants were asked to identify the type of sensors being most used with these I/O products. Flow, pressure, RTD, level, and thermocouple were the clear most cited sensor inputs by the DCS group.

For PC-based system users, there was considerably less use as a percent of the responders, but proximity, pressure, thermocouple, flow, strain gauge made the top five.

The PLC user group was better defined, with proximity, pressure, level, thermocouple, and flow significantly outdistancing other sensor inputs. Figure 3 details the findings.

Discrete and digital signals (on/off) account for the largest average share of inputs and outputs for all three system types. In the PLC world, digital/discrete accounts for 75% of inputs and 79% of outputs. For PC-based systems digital/discrete signals account for 62% of inputs and 80% of outputs, while DCS users reported 58% of inputs and 66% of outputs as discrete/digital.

The data sampling rates reported seem to suggest that PC-based systems are being recognized for high-speed applications. Some 33% of that group reported cycle time needs in a range from 1 millisec to 100 µsec, with another 25% requiring speeds of 10 µsec or faster.

The biggest PLC reporting density (24%) was in the 100 to 10 millisec range, but a full 36% said they need cycle times of 100 µsec and faster. Twenty-nine percent of the PC-based responders reported this need.

The comparative slow pokes, not surprisingly, are the DCS users. The clearly biggest reporting percentage (42%) said they require 100 millisec or slower. Only 16% report rate needs of 1 millisec or faster. Figure 4 provides more detail.

Software Preferences
The VDC analysts asked the study participants to identify the most important features and performance requirements of software they chose for implementing distributed/remote I/O buses/networks.
 Reliability was top of the list for both the PLC and DCS-centric responders, while compatibility with other software and systems was the top requirement for the PC-based group. Ease of programming was the second-most-named requirement of the PC and PLC crowd. Ease of configuration was the named second-most by the DCS crowd. Diagnostic/troubleshooting capability of the software was high on all three groups’ lists. Figure 5 provides more details.

Asked what they most liked and disliked about the software they use for implementing these products, there was unanimity among all respondents: expense and license fees easily were the top two dislikes. Difficulties with configuration placed no lower than fourth on all three groups’ lists.

What they like most carried some variation across the respondent groups. Ease of configuration, ease of installation, and open standards were the top three named among the DCS users. Ease of programming, ease of use, and ease of configuration topped the list of the PC-based community, while Reliability, ease of programming, and open standards were the three most-mentioned by the PLC users. (Figure 6 has more details.)

Another software inquiry determined the most prevalent sources for acquiring the necessary drivers. Not surprisingly, 80% of the respondents go directly to the hardware developers. While less than 10% of the PLC users develop their own drivers, 19% of the DCS users and 28% of the PC-system users say they do driver development for their systems.

Media Attention
Two-wire twisted shielded cable is the runaway most used media today (named by 66%), say the study respondents. Four-wire twisted unshielded is named second-most often (by 47%). Two-wire shielded is seen to decline in use, with 54% (still ranked first, however) expecting to be using it by 2010. The respondents indicate large growth in use of wireless and plastic fiberoptic cable by 2010.

Mounting and Packaging
DIN rail-mounted products accounted for the largest share of the worldwide distributed/ remote I/O market in 2005 for all product classes. On-machinery mounting accounted for the second largest shipment shares for those used with PC-based control systems and PLC systems. The popularity of this mounting configuration is due to the ongoing trend to distributed controls. By locating the I/O modules directly on the machines, users can save wiring costs and have more flexibility with floor plan design. The relatively small share of on-machinery mounting for use with DCSs is related to propensity of use in process controls.

Future Connections
We all know users that are moving away from local I/O hardwired at the controller to distributed/remote I/O connectivity via buses and networks. The study attempted to get a sense of the progression that trend is likely to make during the next several years.

The study respondents say that, at present, local I/O still accounts for the majority of their connections, with 57% of the PLC users, 53% of the DCS users, and 45% of the PC users reporting local hard-wired I/O use. That % is projected to drop to about 40% by 2010 with significant movement in all three groups. The respondents also expect to increase use of devices with embedded interface circuitry during the measured period. Fully one in six of the PC users expect to use that solution by 2010,, up from one in 10 reported today. A breakdown by group is found in Table I

Safety Buses/Networks and I/O
Shipments of distributed/remote I/O having connectivity to safety buses/networks for use in safety controls and safety instrumented systems accounted for only a small portion of the overall market in 2005. Overall shipments of distributed/remote I/O with safety bus/network connectivity totaled $42 million in 2005 and are expected to approach $100 million in 2010. Most of these products are for use in safety PLC system applications.

Safety buses/networks currently in use with distributed/remote I/O include: AS-i Safety at Work, DeviceNet Safety, Interbus Safety, PROFIsafe and Safetybus p.

The shift to Ethernet-based networks also is occurring in the safety bus/network market. Profisafe, for example, is compatible with Profinet. Furthermore, products will be coming on the market for Ethernet/IP Safety, a new safety bus development of ODVA, and SafetyNet, an Ethernet-based safety bus being developed by the Safetybus p Club.

Product Research Habits
Finally, we’re always curious about how technology buyers are getting information about the products they buy and use or embed in their machines.

Given a list of potential information sources, 73% of the respondents named using the Internet as a source of information—the largest response total. Article in trade magazines was noted by 64%, magazine ads 42%. Catalogues continue to have strength as a source: vendor catalogs were noted by 49% of the respondents. One-third mentioned trade shows, and roughly 30% said they use reps, agents or distributors to learn about products. Direct contact with manufacturer sales reps was noted by only 24%.