I/O Modules Get Smaller, Smarter

Just as all roads were said to lead to Rome, much of control engineering connects with I/O modules. People have strong views about their highways, and especially any crossroads. This crossroad is seeing traction in smaller footprints, embedded and distributed intelligence, greater communications capabilities, and easier installation, as well as scalability and flexibility.

By Mark T. Hoske May 1, 2003
Trends in I/O Modules
  • Smaller footprints

  • Embedded intelligence

  • Ethernet, wireless connections

  • Easier to install, use

  • Granular capabilities


Just as all roads were said to lead to Rome, much of control engineering connects with I/O modules. People have strong views about their highways, and especially any crossroads. This crossroad is seeing traction in smaller footprints, embedded and distributed intelligence, greater communications capabilities, and easier installation, as well as scalability and flexibility.

I/O—inputs and outputs—from measurement and actuation go through modules and attached networks to the control logic. Logic also can be distributed or embedded near or close to the point of measurement or actuation, closing the control loop in a very small space. To learn about I/O trends, Control Engineering and Reed Research Group (both part of the Reed Business Information www.reedbusiness.com ) asked subscribers about I/O devices in a March 2003, e-mail/Web-based survey.

Results follow, along with observations, and new products, including four exclusive product introductions from AutomationDirect, National Instruments, Rockwell Automation, and Schneider Electric.

Survey responses were received from 193 subscribers who evaluate, specify, recommend, install, and/or purchase I/O devices for in-plant or OEM (resale) requirements. Discrete input, analog input, discrete output and analog output are the most widely used I/O modules, followed by network interface modules, combination modules, then PID (proportional-integral-derivative) modules.

A bit less PID: Largest change between “currently use” and “plan to use” is an expected 8-percentage point drop in PID modules.

The most widely used network communications connected to I/O modules is presently 4-20 mA at 84%. Results show that Ethernet TCP/IP now at 79% will narrowly secure the top spot within 12 months, moving up to 85%, while 4-20 use will dip slightly to 83%. Other networks currently in double-digit use are 52% DeviceNet, 38% ControlNet; 38% HART, 34% Profibus, 22% FOUNDATION fieldbus; 15% Interbus, and 11% Optomux. FOUNDATION fieldbus had the largest difference between “currently use” and “plan to use” at seven percentage points.

When buying I/O devices, respondents cite technical support, ease of use, and communications as important.

Moving on up: Compared to the June 2002 survey, “communications capabilities and “ability to network” and “on-devie intelligence” each moved one higher in rank order in May 2003.

Prognostication, observation

Jerry Penick, a Rockwell Automation (Milwaukee, WI) manager for distributed I/O, says I/O connections continue to migrate from inside centralized cabinets to on-machine mount style products, reducing the installed cost and costs associated with maintenance and repair. “Likewise, we are seeing intelligence move from centralized locations to the I/O, especially in extremely high-speed applications.” Andy Hoheisel, Rockwell Automation business manager for distributed I/O, says on-machine design also reduces wiring and system costs. “OEMs and end-users want to see a common look and feel when programming/ designing systems,” Mr. Hoheisel adds. Listening to customers enhanced DeviceNet capabilities (see product on page 60).

Having more I/O devices distributed, intrinsically safe, networked, and smart means going beyond “I failed,” to “I’m about to fail,” says Connie Chick, GE Fanuc (Charlottesville, VA) controller and I/O manager. Predictive intelligence prevents down time and saves end-users money. Cost considerations still reign, Ms. Chick says.

Smarter oil pumping

Todd Walter, National Instruments (Austin, TX) industrial control and distributed I/O product manager, also promotes the intelligent line of thinking. For instance, on a European Shell Oil drilling platform, LabView Real-Time software runs on Compact FieldPoint I/O modules to measure oil and natural gas pressures and levels. “The software predicts when the separator tank is going to receive a slug of oil or a pocket of high-pressure natural gas and controls a pre-separator tank to allow faster production ramp-up while avoiding separator-tank overflow.” Complex algorithms would be difficult to create without PC-like software, he says.

Ed Rogin, a manager for distributed I/O at Siemens Energy & Automation (Norcross, GA) is seeing an increase in I/O module use from the process industries. “We have been working on adding higher capabilities in our function and analog types of modules. We also have a variety of motion-control and stepper and drive controls that customers add to regular I/O nodes, avoiding the need for specialized components. We’re increasing the variety of what’s available.”

Mr. Rogin cites demand for more diagnostics, hot-swap capability and modules with higher current ratings and says the trend is toward more flexibility, functionality and uptime. There’s growth in modules with 1-4 points and less interest in higher-density I/O blocks. Smaller segments allow faster setup, and quicker troubleshooting once running, he says.

When you’re at the crossroads of your next project, rev up with the most-appropriate I/O modules to connect to success.

I/O module products

For more manufacturers, visit www.controleng.com/buyersguide . For system integrators go to www.controleng.com/ integrators .

Comments? E-mail MHoske@cfemedia.com

Exclusive: network modules for nano, micro PLCs

Three advanced networking modules for the DL05 nano and DL06 micro lines of PLCs are the H0-ecom Ethernet Communications Module, D0-devnets DeviceNet Slave Module, and the H0-pscm Profibus Slave Module. H0-ecom Ethernet Communications Module is said to be a cost-savings breakthrough for a high-speed PLC communication module. At $169, it provides a 10 Mbit Ethernet link for PLC systems and can be used for peer-to-peer PLC communication between two or more DirectLogic PLCs or between DirectLogic PLCs and PCs. It is offered in 10BaseT, using standard RJ45 modular connectors and supporting UDP/IP and IPX protocols. It can do online programming of DL05/06 PLCs using DirectSoft32 over Ethernet, and simultaneously serve data to HMI/SCADA and information systems using OPC over Ethernet.

D0-Devnets DeviceNet Slave Module, at $75, makes any DL05 or DL06 into a smart node on a DeviceNet controller network. It installs into the PLCs’ option card slot and collects and reports I/O data to a DeviceNet master.

H0-pscm Slave Communication Module allows either PLC to be networked to any Profibus DP Master. At $259, it offers selectable data rates from 9.6 K to 12 MB, depending on network length. www.automationdirect.com AutomationDirect

Exclusive: More than double DeviceNet capabilities

Rockwell Automation more than doubles DeviceNet networking capabilities for Allen-Bradley 1734-adnx Point I/O Expansion adapter. The 24 V dc network interface adapter with subnetwork expansion increases DeviceNet’s reach from 500 m to 1,500 m, and, depending on scanner capability, from 63 to more than 126 nodes per scanner. Adapter connects the main DeviceNet network to a controller scanner module and a DeviceNet subnet link with products that comply with Open DeviceNet Vendor Association requirements. Subnets are interconnected, independent, segments or domains, which can expand network size, performance, and security. Users can double the physical length of their Logix-based DeviceNet system and reduce wire runs from field sensors/ devices to a single network link by adding a node capable of interfacing to devices up to 500 m from the 1734-adnx. A subnet can have up to 63 nodes per scanner. Troubleshooting sensors/devices can be faster by isolating zones from the main DeviceNet trunk. The trunk can be configured for change-of-state operation. www.rockwell.com Rockwell Automation

Exclusive: Modules get advanced digital functions

Four new advanced digital modules are available for Compact FieldPoint and LabView Real-Time control applications. Small, rugged eight-channel digital modules can withstand high shock, vibration and wide temperature ranges, for high-speed counting, pulse-width modulation (PWM) control, and pulse-train generation. The cFP-CTR-500 and cFP-CTR-502 are digital high-speed counter modules, delivering eight counter channels, four gate inputs and four digital outputs. Input signals extend to 50 kHz; internal frequency reference or external gate inputs can be used for frequency measurement. Counter modules work with 5, 12, and 24 V dc sourcing and sinking devices. Configurable, low-pass filters eliminate high-frequency noise. Cascadable counter channels allow up to 128-bit, high-resolution counters to store trillions of counts. The cFP-PWM-520 delivers eight PWM output channels with independently programmable duty cycles for PWM-based control applications. The cFP-PG-522 pulse-generator module provides eight outputs that can generate finite or continuous pulse trains with programmable frequency and duty cycle. Prices start at $375. https://ni.com/compactfieldpoint . National Instruments

Exclusive: Distributed I/O eases device integration

Schneider Electric, in October 2003, will launch a unique, all-in-one IP20 distributed I/O platform that incorporates an improved wiring solution, power management, and device integration system. Modular Telemecanique Advantys STB platform is one of the first distributed I/O platforms with local level reflex functionality for high-speed logic solving, independent of the PLC master. Open, plug-and-play architecture allows one fieldbus node to distribute I/O across an entire machine, with interface to any standard fieldbus. Separate power for input and output devices eliminates the need for extra terminals and protection devices. Small form factor assures high granularity and optional integral diagnostics simplify troubleshooting. www.schneiderelectric.com Schneider Electric

Intelligence eases maintenance

DRT2 smart DeviceNet slave provides first-in-the-industry capabilities for monitoring I/O status and network communications status, according to Omron Electronics. It allows users to remotely monitor and diagnose low network voltage, communications errors, and shortcircuits for connected devices, providing preventive maintenance and troubleshooting abilities. With Omron Configuration Software users can connect and monitor the factory floor network over an Ethernet connection without control programming or interruption. Prices start at $225. www.info.omron.com . Omron Electronics

Distributed I/O modules

New modules for VersaPoint distributed I/O system connect easily to a variety of PLC, DCS and PC-based control systems and allow users to tailor the number I/O points per application. Snap-on modules combine the cost-per-point benefits of a higher density I/O system with flexibility and reduction of spare points. They offer higher-density discrete input and output capabilities, negative logic discretes, additional analog input and output options, a high-speed counter input, and new power and segment terminals with built-in fusing and diagnostics. Communications include DeviceNet, Profibus-DP and Ethernet. Design can yield 50% space savings and reduce wiring up to 80%. www.gefanuc.com GE Fanuc Automation

I/O line gets HMI, PID, OPC

Snap I/O lines expand with upgrades to automation and data acquisition software, with PID control, subroutines, and enhanced security and performance. “ioDisplay 2.0” is a new graphics-based human machine interface software package. “ioControl 2.0” for Snap Ultimate I/O system is flowchart-based control programming software, with an enhanced debugger for easy PID loop tuning. OPC Server 2.1 provides easy, standard integration of the mentioned I/O systems with any OPC-aware software client ioControl 2.0 comes with the Snap Ultimate I/O system; ioDisplay 2.0 is $99 per seat. www.opto22.com Opto 22


A list of most-purchased-from vendors, and products—including the following—to come soon.

Phoenix Contact wireless I/O modules

Moore Industries-International: Process control Ethernet I/O network

Siemens Energy & Automation