Thinking outside the box about the future of I/O systems
Trends in I/O Devices Ethernet as a fieldbus Flexibility Integration of safety components Thinking outside the box has become a metaphor for daily life. Whether it's providing creative answers to everyday problems or placing a new emphasis on various areas of a plant floor, thinking outside the box sets new ideas in motion.
Trends in I/O Devices
Ethernet as a fieldbus
Integration of safety components
Thinking outside the box has become a metaphor for daily life. Whether it's providing creative answers to everyday problems or placing a new emphasis on various areas of a plant floor, thinking outside the box sets new ideas in motion.
Input/output (I/O) devices have also undergone change due to industries' need to think outside the box. Today's end-users are looking beyond remote I/O systems and desire, among other features, flexibility, increased intelligence, and open yet tightly integrated systems.
George Ziegler, business development manager for Schneider Electric (North Andover, Mass.) says, 'Flexibility has always been an issue with I/O devices. They have traditionally been designed to work within a particular manufacturer's preferred network or configuration. As a consequence, flexibility was limited.'
More intelligence, scalability
Louis Szabo, strategic applications manager, distributed I/O systems, for Rockwell Automation (Mayfield Heights, O.) says, 'For I/O devices, users have desires in three areas; power to the I/O devices, packaging, and intelligence. In these days of rolling blackouts and power shortages, we find a lot of customers concerned about clean power being applied to all field devices and as a result look to us to provide local DIN-rail mounted power supplies.
'There's also a growing trend toward offloading some of the burden on the controller by embedding more intelligence into the local I/O device itself,' he adds.
In February 2001, 100 phone interviews were conducted among Control Engineering professionals to measure their involvement in selecting and using input/output devices. Some specific areas studied were:
Types of I/O devices used and applications; and
Current and future I/O device purchases.
Following are highlights from the survey:
Forty-percent of respondents' primary application of input/output devices is both continuous and batch processing; 20% said discrete products for manufacturing; 18% continuous processing only; 10% batch processing only; 5% utility services; and 6% responded their primary application was for other uses.
In answer to what types of I/O devices are currently used, 85% responded a combination of analog input and output; 80% said a combination of discrete input and output; 75% use network interface; while 70% responded motion control. (See graph.)
When asked what best describes their application of I/O devices, 23% of respondents answered they apply the devices in DCS systems; 18% responded for DIN-rail mounted from PLC controller supplier applications; 17% said for DIN-rail mounted from supplier different from controller; 15% apply I/O devices for PLC systems; 14% for PC-based systems; 6% distributed I/O systems; and 2% responded they use I/O devices for single-point applications.
While type of I/O system used depends on the application, end-users also desire convenience, reliability, and accuracy.
Chris LeBlanc, product group manager for National Instruments (Austin, Tex.) says, 'When it comes to I/O systems, accuracy and calibration are two very important concerns shared by end-users. The trick is to find an I/O system with high quality measurements for more than just analog input but also thermocouple, RTD, and analog output.'
Moreover, Bill Arnold, I/O product marketing manager for Omron Electronics (Schaumburg, Ill.) says, 'Debates over field network technology over the past several years have made users aware of costs of installing traditional I/O systems. Users want to maximize their return on investment.
'They want their I/O devices to be compatible with multiple systems, to have future capability for enhancement. and to feature ease of maintenance,' adds Mr. Arnold.
Mr. Szabo says, 'Ethernet is getting a lot of attention in the industry these days, but users realize there are a lot of flavors of Ethernet that can make actual installation and operation a real headache. We believe EtherNet/IP protocol will help resolve that by providing a common flavor for all devices.'
Finally, Mr. Szabo added that Rockwell Automation expects to see continued growth in DeviceNet, ControlNet and EtherNet/IP for the foreseeable future, with many plants using combinations of the networks to meet specific needs.
Future out of box interests
Jeff Frekot, product manager for controllers and I/O development at Phoenix Contact (Harrisburg, Pa.) says, 'Different markets have different successes and applications, but the simplest protocol is 4-20 mA. Recently, there has been a strong interest in DeviceNet and Profibus due to an expansion of product offerings and I/O compatibility with Phoenix Contact and other manufacturers.'
There has also been a growing trend towards use of PC-based systems and specialty modules for I/O devices.
Paul Ruland, PLC and I/O product manager, AutomationDirect (Cumming, Ga.) says, 'Increased demand in specialty I/O modules has been most notable in the areas of motion control and device-level network connectivity. Advancements in microprocessors and the acceptance of Flash ROM are allowing high-speed counting modules to be designed as mini-coprocessors that use technology developments that provide more cohesiveness between software and hardware.'
Bryan Moore, product specialist for Entrelec (Irving, Tex.) adds, 'There is an increased interest in PC-based control. However, there is concern about its reliability. Most users have seen the white box on their desk lock up or blue screen. Increasing the reliability of the host PC is important.'
Rockwell's Mr. Szabo agrees with the viability of PC-based systems. He admits that while there are concerns about the support from smaller vendors and the reliability of both hardware and operating system, PC-based systems are here to stay and will become more common.
While 66% of respondents believe the purchase of I/O devices will remain the same in next 12 months, we can be assured that end-users will continue to expect manufacturers to think outside the box.
National Instruments' Mr. LaBlanc says, 'To make an end-user successful, the out-of-box experience must convey confidence that they will be able to configure, program, and maintain their system. They need to know that their system is scalable in the event their application requirements grow.'
I/O Devices Products
For more information on I/O device products, circle the following numbers, or visit www.controleng.com/freeinfo . For a wider listing of manufacturers, go to Control Engineering Buyer's Guide at www.controleng.com/buyersguide .
To see archived Control Engineering Technology Webcast on 'Next generation I/O,' go to www.controleng.com/webcast .
Coupler networks to Profibus
Harrisburg, Pa. -Profibus Fieldbus Coupler, IL PB BK, allows inline modular I/O points, inline safety relay modules, pneumatic valve manifolds, machine mountable I/O solutions, AS-I or Loop 2, to be networked to a Profibus system. In addition to standard diagnostics, actual location and cause of error can be reported to the Profibus master by a device-related diagnostic telegram, which can be interpreted and evaluated by the controlling application software program. The coupler is UL listed and approved for hazardous locations as Class I, Div. 2, Groups A, B, C, D. www.phoenixcon.com
Phoenix Contact Inc.
Modular system allows I/O addition
Charlottesville, Va.-VersaPoint is a modular I/O system that allows the user to add I/O points in 1, 2, 4, 8, or 16 increments. Low point counts afford users the flexibility to specify the number of I/O needed for each application and appeals to applications where a wide variety of I/O points are required, but cost is critical and space is limited. VersaPoint I/O provides connectivity to standard remote I/O networks such as DeviceNet and Profibus-DP. www.gefanuc.com
Communication across long distances
Schaumburg, Ill.-Wireless DeviceNet allows users to connect to any DeviceNet-compatible product. Multiple wireless masters can be placed on a single network, which makes multiple, flexible topologies available on the same system. Its spread-spectrum technology makes the signals resistant to interference, allowing the message to get through the first time. The antenna diversity feature in Wireless DeviceNet is said to guarantee that for indoor applications, the direct line of sight signal is the one detected, rather than a reflective signal that may lose information. Target applications include material handling, conveyor systems, assembly lines, and moving equipment where wiring is impractical. www.omron.com
Modules for micro PLCs
Cumming, Ga .-AutomationDirect now offers DeviceNet Slave modules for its DL105 Series micro PLCs. The ac-powered modules are priced at $245 each and connect to any DeviceNet master. Slave modules provide powerful relays, high-speed I/O modules, support polling, and explicit messaging. Enhanced I/O control is said to be possible with four high-speed I/O modes that run in concert with DeviceNet commands. www.automationdirect.com
Pluggable connectors for I/O system
Germantown, Wis .-Modular, pluggable connectors for I/O System 752 can be prewired, allowing use of cable harnesses in panel designs. I/O devices are arranged in groups of eight per pluggable connector. The result is said to be faster wiring time and easier testing. The field side of the connectors is equipped with the vibration-proof and maintenance-free cage clamp connection. I/O System 752 is an addition to Wago's line of modular I/O products, and is available for Profibus, Interbus, DeviceNet and CANOpen. www.wago.com
Controllers usable in harsh places
Stamford, Conn. -CN3440 wall/pipe-mount universal process controller is a versatile, single-loop controller packaged in a field-mounting housing. With a NEMA-4X rating, the controller can be mounted next to a process, even in harsh environments. The instrument has extensive control and I/O capabilities fitted as standard, allowing it to be rapidly configured for almost any application. Other capabilities include autotune PID control, comprehensive setpoint profiling, and one controller for every PID control application. www.omega.com
Cards allow high resolution, small size
San Diego, Calif. -PCI-DA12 Series of digital-to-analog converter cards for PCI Bus computers are low-cost, half-size cards available with two, four, or six double-buffered outputs with 12-bit resolution. Output voltages include standard 0-2.5 V, 0-10 V ranges, as well as www.acces-usa.com
Acces I/O Products Inc.
Carlisle, Pa. -Logic signal inverter converts sensor input/output signals from positive logic (PNP) to negative logic (NPN) devices and vice versa. The inverter is compact and DIN-rail mountable for use in industrial control applications. It is said to provide an easy, convenient solution for linking sensors and controllers with incompatible dc signals.
Modules Add to I/O Family
Mayfield Heights, O .-Rockwell Automation will introduce a series of new thermocouple and RTD modules and new analog voltage modules for its Point I/O family of I/O solutions. Point I/O family consists of terminal bases with removable terminal strips, I/O modules, and network interface options that are DIN-rail mounted and snapped together to meet an application's needs. The thermocouple module features channel-to-channel isolation and cold-junction compensation (CJC) sensors built into the terminal base. Point I/O modules have DeviceNet networking compatibility and will be available with ControlNet and EtherNet/IP compatibility in future releases. Analog voltage modules are used for feedback from speed measuring and positioning devices. They can generate up to 10 V of user-specified excitation voltage for strain gauges, and also read mV values from strain gauges and similar devices. Both modules will be available in July 2001. www.automation.rockwell.com