I/O modules on continuous improvement path
I/O modules on continuous improvement path
Input and output (I/O) module manufacturers are not resting on their laurels. The unsung devices that are tucked away in enclosures and scattered about the plant floor are seeing steady improvement in communications, integration ease, and density, among other areas.
Not only do I/O modules provide the necessary connections between sensors or actuation devices and the site of control logic, thereby closing the control loop, they also are adaptable to a wide variety of communication protocols, physical constraints, and physical-layer connections. I/O modules, like all other control system devices, must be applicable to in-plant expansions and control-system revamps.
Built-in scalability, flexibility, and backward compatibility are considered prerequisite, and are qualities reflected in the products described below. I/O module manufacturers have done their homework and continue to provide control engineers with a variety of versatile connectivity devices.
Trends in I/O modules were covered in an August 2004 email/Web survey by Control Engineering and Reed Research Group-both part of Reed Business Information . The study queried subscribers about preferences in I/O devices, including technological preferences and purchasing patterns. Results were based on 177 qualified responses from readers involved in specifying, recommending, and/or buying I/O devices.
Use is universal
As might be expected, I/O devices are widely used in industry for both in-plant requirements and OEM applications. The majority appear on the plant floor. The survey showed that 52.8% of those specifying and buying I/O devices did so as part of in-plant control system requirements. Specifiers that bought them for OEM (resale) machine control systems accounted for 17.1% of the total.
Breakdown of primary applications for I/O devices mirrors the trend set in the purchasing requirement portion of the survey. Continuous processing and batch operations, both in-plant operations, account for nearly three-quarters of I/O applications. The largest application category was both continuous and batch processing operations at 45.2%. Continuous processing accounted for 22.9% of the responses and batch processing only, 4.8%. Discrete products manufacturing applications represent 15.7% of total responses.
The preponderance of I/O modules used in process operations is entirely understandable. In the process world, I/O points can involve analog devices and valves, often many of them. These require more adjustment and have multiple failure scenarios when compared to discrete manufacturing sensors and related devices. Ability to handle both analog signals and diagnostics is required in these control schemes. In continuous processing, availability is an important issue. If data tell that a sensor is about to fail or a valve is about to “hang up,” users can perform maintenance before the fact and prevent or shorten downtime. High I/O counts are the hallmark of process systems for this reason.
According to survey results, the “ability to network as a very important reason to specify and buy I/O devices” took a dramatic jump from the previous survey done 11/2 years ago—up to 57% from 47%, while most other characteristics remained about the same (see accompanying bar graph). Connie Chick, business manager for controllers at GE Fanuc (www.gefanuc.com) explains the growing interest in networking, especially in continuous process, by saying, “In the process world, high availability is critical; no DCS runs without it. Anything, such as smart devices, that can help that process stay up makes the investment extremely worthwhile—something that discrete manufacturers might sometimes debate. As programmable automation controllers move more into hybrid and the edge of pure process, they will see networking requirements.
“Increased security concerns have been getting more attention lately,” Chick continues, “This also leads to a requirement for more diagnostic data from field devices. As costs of smart devices go down, speeds of fieldbuses go up, and networking becomes easier to manage through software configuration and control, we will see more central processing units with many network connections to devices.”
Future I/O modules
So what is on the horizon for I/O module technology? According to Larry Komarek, automation product manager for Phoenix Contact (http://www.phoenixcon.com), I/O form factors are evolving and incorporating new connection and communications technology to lower the installed costs for more application situations.
“In the past, only PLC rack mount I/O modules were available. Now both machine OEM and manufacturing process users employ modular manufacturing approaches that consist of using standardized function assemblies, each containing the control, mechanics, and software routines. Subassemblies are manufactured and combined to form custom solutions in much less time than the traditional separation of control and mechanical/process engineering. The highly modular approach is driving the need for different I/O structures: highly modular and configurable I/O for main control cabinets, small low-cost fixed I/O blocks for junction boxes, and enclosureless IP67 I/O for highly modular assemblies,” Komarek continues; “The ability to mix fieldbus compatible modular vs. block I/O with IP20 and IP67 ratings allows the lowest installed cost with the ability to quickly (and affordably) respond to changes in customer demand.”
Other possible changes
Connection and communications technology innovations are fueling I/O system innovations. Examples of this include slice-style modular I/O connection schemes that reduce I/O station wiring time by eliminating countless module-to-module wires required by traditional rack I/O devices. For IP65/67 I/O systems, new M12 connectors are emerging that reduce connection time by up to 90% by connecting in less than one turn vs. many turns for conventional M12 systems. “While saving a few turns may not at first seem significant, multiply the time savings by total number of connections in a large I/O-count system, and the savings adds up quickly. Fast IP67 connection technology also reduces the chance for a poor watertight connection that allows slow fluid entry and helps prevent production-disrupting failures,” Phoenix Contact’s Komarek adds.
Demise of 4-20 mA?
According to survey results, Ethernet TCP/IP was the communication network most often cited for respondent’s current and future I/O networking needs. The old standby, 4-20 mA, was second choice in both categories. According to Todd Walter, data acquisition group manager for National Instruments , this response is not unexpected.
“In recent years, there has been a significant trend in the automation market to adopt PC-based technologies and standards. The boom of the computer in office and consumer applications has created reliable and low-cost components that have been heavily leveraged by the automation market. Historically, 4-20 mA communication was used because of its ability to detect open circuits and for its immunity to signal losses that voltage transmissions experience over long distances due to line resistance. However, with the adoption of PC-based technology into automation applications, communication with various devices and transmitters on the network is now almost exclusively digital. And because Ethernet has become the defacto network communication standard for the PC, it has also been adopted by the automation market,” Walter notes.
“Specifically, Ethernet has begun to dominate the controls market as a high level communication bus due to its high bandwidth and ability to handle multiple communication protocols, including Modbus, TCP, FTP, HTTP, and others. In fact, Ethernet is only one of the many technologies adopted from the PC industry into automation,” Walter adds.
For more manufacturers, visit www.controleng.com/buyersguide; for system integrators, click here . Also visit the Web sites listed.
Flex I/O family expands
By expanding its family of Allen-Bradley Flex modular I/O products, Rockwell Automation has given system designers and end-users more connectivity, enhanced diagnostic capabilities and new options and certifications that meet the needs of hazardous-location applications. The line now includes 8-point input (IE8H) and output (OE8H) HART analog modules that allow communication with “smart field” devices that support the popular HART protocol. Modules can access the HART digital signal in parallel to the module’s 4-20 mA analog signal with no effect on analog-signal processing. Modules allow users to connect to ControlNet or EtherNet/IP networks, HART field devices, HART handheld programming terminals, Rockwell Automation controllers, human-machine interface (HMI) products, and Field Device Tool (FDT)-compatible software. Other features include digital diagnosis, conformal coating, and UL/cUL hazardous location certification.
Module links I/O, PC via Ethernet
T1H-EBC100 module provides a high-performance Ethernet link between the company’s Terminator I/O products and PC-based control software, or WinPLC/DL205/DL405 CPUs using its Ethernet Remote Master module. The module supports TCP/IP, UDP/IP and IPX at 10/100 Mbps. It also supports Modbus TCP protocol, said to be the most widely used open protocol in industrial manufacturing, at 10/100 Mbps. The module can be configured using an Internet browser to access the module’s HTML configuration page. This configuration method uses the TCP/IP protocol, and the module’s IP address must be known to establish communications. NetEdit3 software can be used to verify the module’s IP address and to configure the module.
Ethernet process control, distributed I/O network goes wireless
When wires can’t be run for practical or economic reasons, the Wireless Link Module (WLM) provides accurate and reliable wireless connectivity between remote field sites. This bi-directional, spread-spectrum wireless module employs Intelligent Spectrum Frequency Hopping technology and 32-bit CRC error correction for secure, robust communications. Available models support Ethernet or serial communications, and operate at FCC license-free frequency ranges of 902 to 928 MHz or 2.4 to 2.483 GHz. The WLM is ideal for use with its developer’s NCS NET Concentrator System (NCS), as well as similar process control and distributed I/O systems. NCS process control and distributed I/O system provides 20-bit measurement resolution; signal-conditioning capabilities are said to equal the highest-quality transmitters on the market. Data rates up to 100 megabits per second are available.
Moore Industries-International Inc.
I/O family is high-performance, simple, affordable
Telemecanique Advantys OTB is the latest addition to a family of modular distributed I/O products from Schneider Electric. These I/O devices have been optimized for use in modular distributed I/O architectures. Advantys OTB are also said to meet the requirements of machine manufacturers and users who seek the best compromise between size, ease of installation/cabling and costs. Open and modular, these I/O solutions enable OEM manufacturers to create small and medium-sized I/O islands, managed by a master controller over a fieldbus or communications network. Distributing I/O devices and logic closer to sensors and actuators reduces wiring time and costs for modular machines. Three module communication bases work with CANopen, Ethernet TCP/IP, or Modbus RS-485 serial line. Inputs and outputs are integrated into each interface module.
Smart I/O terminals for DeviceNet
According to Omron Electronics, users can monitor more than I/O status using DRT2 “smart” DeviceNet slave terminals. Available as discrete, analog, and IP67 sealed-discrete input and output modules, DRT2 slaves collect valuable information that can be used in preventive maintenance programs to reduce unexpected shutdown due to component failure. Users can also remotely monitor automatically collected data using Omron’s DeviceNet Configuration Software. All devices offer communications supply voltage monitoring and a communications error log. Analog I/O terminals provide scaling, integration, and comparator functions. Discrete modules have 16 input or output points, optional 8-point expansions. IP67 sealed-discrete modules have 8 or 16 inputs, or 8 outputs. Analog modules have 4 inputs or 2 outputs in various selectable voltage and current ranges.
Omron Electronics LLC
Universal analog I/O module
PACSystems RX3i Universal Analog module offers functionality of four modules in one to reduce I/O space requirements, decrease spare parts and inventory, and simplify wiring and configuration. It also provides up to 30 types of analog input configurations. Channels can be individually-configured using Proficy Machine Edition software for developers, providing any combination of up to 8 channels of voltage, current, thermocouple, RTD, and resistance inputs. Modules are software-configurable, require no module jumpers to set, provide six filter frequencies, and are individually selectable by channel. They also feature rapid channel acquisition times based on filter frequency, full auto-calibration, on-board error-checking, module hot-swap support, open-circuit detection for most input types, and short-circuit detection for RTDs. Also featured is resolution at 24-bit ADC converted to floating point or integer, scaling in engineering units, alarms and rate of change alarms, configurable CPU interrupts, and flash memory for future upgrades.
Next generation of multifunction DAQ devices
National Instruments now offers a new generation of multifunction data acquisition (DAQ) products based on the newly designed NI-STC 2 system controller chip and NI-PGIA 2 amplifier technology. M Series multifunction DAQ devices offer increased accuracy, faster sampling rates, more I/O channels, and features previously unavailable in multifunction DAQ devices. These devices are said to lower the cost per I/O channel and reduce overall system costs by minimizing setup time using development tools included in NI-DAQmx measurement services driver software. Applications include test, control, and sensor measurement. The core of each M Series device is the new NI-STC 2 synchronization and timing controller, which allows up to six operations to execute simultaneously at throughput rates up to five times faster than previous DAQ devices. The redesigned NI-PGIA 2 family of programmable gain instrumentation amplifiers dramatically reduces settling time to ensure accurate measurements even at the fastest scanning rates, NI says. In addition, M Series DAQ devices offer up to 32 18-bit analog input channels, four 16-bit analog outputs, two 32-bit counter/timers, and 48 digital I/O lines.
I/O system upgrade
ABB Automation Technologies
ABB has upgraded its original automation I/O system. S400 I/O is a direct replacement for previous technology and is compatible with the current ABB I/O system, the S800 I/O. The replacement system is based on the newer S800 design, yet is a direct replacement for the original S400 I/O systems. The upgraded S400 is said to be capable and reliable in the field and able to support current industry-standard fieldbuses. New units have the same footprint and field-cable connector socket locations as the old ones, simplifying replacement. Existing field cable need not be changed or relocated. According to the company, the new S400-to-S800 I/O upgradeexpands functionality, flexibility, reliability, and self-diagnostics, and provides accessto fieldbus technology.
ABB Automation Technologies
Distributed I/O provides IP20 protection
Siemens Energy & Automation
Siemens Energy & Automation’s Simatic ET 200S distributed I/O now delivers IP 20 field-level protection for Ethernet. ET200S can now use Profinet, the Profibus International industrial Ethernet offering. Profinet is real-time Ethernet that encompasses all aspects of automation, including I/O, motion, machine cell connectivity, and safety. When combined with Siemens IM 151-3 PN ProfiNet interface, the ET 200S I/O operates as distributed I/O controlled via Ethernet, including analog signals, counters, serial interfaces, motor starters, frequency converters and pneumatics. Replacing the ET 200S I/O is quick and easy thanks to a plug in, micro memory card available with the Profinet interface, which eliminates need for a programming device. Bus interface connections can also be made or terminated with the Profibus interface in less than 30 seconds with Siemens FastConnect technology.
Siemens Energy & Automation
High-density input module
Snap-HDIDC-32, a 32-channel digital input module, is used with Opto 22’s Snap Ethernet systems for local and remote monitoring, discrete manufacturing, process control, and data acquisition applications. Snap-HDIDC-32 is said to offer a new level of density for users with high digital I/O point count applications, or for those who require more than 64 points in a single location or I/O rack. The module also reduces the per-point cost of digital I/O systems by providing up to eight times the number of I/O channels in the same space. It provides 32 optically isolated channels of status input and can be used to sense on/off status for low ac or dc voltages from proximity switches, limit switches, push buttons, pilot switches, and other sources. Snap-HDIDC-32 is also ideal for detecting low-voltage auxiliary contacts. Automatic latching is also included.
Inline block-style I/O modules
Block I/O modules include 16- and 32-channel digital block modules and are compatible with a number of fieldbus protocols including Interbus, Profibus DP, DeviceNet, CANOpen. The compact design of the Inline Block I/O modules allows them to be easily installed in distributed control panels or control cabinet doors. The 2-in. high Inline Block I/O modules are said to be ideal for smaller control cabinets. Installation is said to be easy; I/O and communications are integrated into one low-cost unit. Sensor and actuator cables are also easily connected without tools through use of removable wiring arms. Start-ups with the Inline Block I/O station are simple because of extensive diagnostic indicators, data, and use of color-coded wiring indications, which also minimize maintenance and wiring errors.
Phoenix Contact Inc.
Capture process-upset events
Emerson Process Management
Sequence of Events (SOE) I/O cards are used to capture process-upset events from field devices. Because events are captured and temporarily stored locally on the SOE I/O card, faster recording is possible for each channel on the card. Events captured by an SOE input card are time stamped using 1/4-ms resolution. The DeltaV controller resolves time stamps to ensure accuracy across the network. Events are stored electronically so the user always has easy, reliable access to the data that can be displayed in chronological order. All data can be automatically exported as well, so that it can be read with Microsoft Office applications. The I/O card can be paired with a 32-screw or a mass termination block. Pending certifications include CE, CSA, FM Class 1, Div. 2, Groups A, B, C and D.
Emerson Process Management
Combination I/O module
Model ET-MIX24880-D has a double-density design that provides 24 discrete inputs and/or eight discrete outputs, and eight analog inputs in a single compact module. ET-MIX24880-D joins the family of EtherTrak I/O modules while providing direct Ethernet and/or RS485 connectivity, which can be used as a redundant backup communication path. Use of the new ET-MIX24880-D instead of individual modules for each I/O type, saves space, reduces installation time, and lower costs. The module has a 16-bit A/D converter for precision measurements and hot-swap capability. Engineered to withstand the abuse of harsh industrial environments, the ET-MIX24880-D is vibration and surge resistant, operates in temperatures ranging from -40 to 70 °C, and is CE, UL, CSA, and Class 1, Div. 2 (Zone 2) rated. The module also has Det Norske Veritas No. 2.4 (Class A & B) certification for marine and offshore use.
DIN-rail-mounted I/O modules
Automation Systems Interconnect Inc.
Automation Systems Interconnect Inc. announces expansion of the line of DIN-rail-mounted input/output modules used with PLCs, CNCs, and industrial controllers. Latest additions include modules designed for use with GE and Siemens controllers; others are available upon request. The modules feature 24 V dc or 110 V ac inputs, current ratings of 5 to 10 amps, SPST, SPDT, or DPDT contacts. They also feature from 4 to 40 relays in one package depending on configuration and model. Additional features include terminal block, ribbon cable or D-sub connections, fuses, and LED indication.
Automation Systems Interconnect Inc.
Sensor-level I/O network
CC-Link/LT is a sensor-level network version of the device-level network CC-Link. CC-Link/LT can reduce the cost of connecting simple digital devices, such as pilot lights, limit switches, and pushbuttons, to a controller. CC-Link/LT takes the network to the I/O device and eliminates discrete wiring runs, saving system costs and cost of installation and maintenance. CC-Link/LT requires no cutting or stripping of cable to make network connections with simple-to-use insulation displacement connector termination. Connection to I/O blocks from field devices can also be made with IDC connections, eliminating the need for wiring lugs and associated installation work. CC-Link/LT is said to outperform other sensor level networks, spans over 1,600 ft, and handles up to 1,024 sensors per network. Trunk and drop line topology saves cable by eliminating return loops from I/O drops. No special programming is required because all I/O appear local to the controller.
Mitsubishi Electric Automation Inc.
Custom I/O modules
Control systems can have connectors used with logic control equipment because they might have been developed incrementally over time, or because users need specific components to meet particular goals. In these cases, establishing reliable communications with standard interfaces can be difficult. Due to a lack of universally followed standards for logic control elements, remote terminals, and industrial PCs, users may need special physical connectors for physical layer connectivity between the far-end sensors and actuators, and the logic control elements in use. In applications where customized I/O modules are required to establish this physical layer path, Weidmuller can provide custom I/O modules solutions so users can get the exact combination of features to address specific application needs. Weidmuller manufactures I/O modules to customer specifications; such modules are more robust, accurate, and cost-efficient by design, the company says.
Ethernet Fieldbus coupler
The 750-341 Ethernet Fieldbus Coupler provides EtherNet/IP connectivity for Wago-I/O-System 750 I/O modules. The fieldbus-independent I/O modules are combined on the DIN rail with the fieldbus coupler to provide a cost-effective distributed I/O system with maximum flexibility, Wago says. The coupler automatically configures itself on boot-up and creates a local process image that may include analog, digital, or specialty modules. All connection points feature its developer’s Cage-Clamp wire terminals for fast and secure, vibration- and corrosion-resistant connections. Each coupler takes 128 connections.
Low-cost PC/104 utility board
Acces I/O Products Inc.
Model 104-IDIO-16 is a low-cost 32-channel PC/104 utility board featuring 16 optically isolated inputs and 16 optically isolated solid-state outputs. Isolated, non-polarized inputs may be driven by 3-31 V dc sources (or higher by special order) or V ac sources at frequencies of 40 Hz to 10 kHz. Optically isolating digital inputs from each other and from the computer ensures smooth, error-free data transmission in noisy, real-world environments. The 16 input channels are available via a 34-pin IDC type header. Fully protected solid-state outputs, capable of driving 1 amp each, are said to be inherently more reliable than electromechanical relays and give system architects a more robust product for designing the control circuitry. Solid-state outputs are available via a 50-pin IDC type header.
Acces I/O Products Inc.
Gateways meet ODVA requirements
Pepperl+Fuchs’ new AS-Interface DeviceNet Gateways have passed Compound Version 18 of the ODVA conformance test. VBG-DN-K5-D single-channel gateways and VBG-DN-K5-DMD dual-channel gateways provide diagnostic capabilities while supporting polled I/O points and change-of-state operations. Additional features include detected slave display, visual fault diagnostics, support for analog I/O points, and ability to network safety devices, such as emergency stops and light curtains up to Category 4. Gateways are the core of the wiring system and connect AS-Interface to upper-level controllers. They handle the complete data transfer, cyclically polling all participants connected to the wiring system. The gateway can be placed anywhere in the AS-Interface segment. The single-channel version can handle 248 inputs and 186 outputs over 62 addressable I/O modules. The dual-channel gateway has 496 inputs and 372 outputs.