Distributed Digital I/O Solves Problems

Oct. 19, 2010
It's Hard to Overlook the Benefits When You Move Away From Hardwired Control Systems

Some machines still use hardwired I/O components and run points back in cable trays to motor control centers and PLC combinations. This approach has advocates vs. on-machine components with instruments wired via a digital protocol.

"The advantages are cost saving and being able to distribute, so you have redundancy," says Eric Rice, director of technical support for North America, Intelligrated ( in Cincinnati. "If one of the main cables is cut, there's no downtime. If someone with a fork truck severs wires in a centralized control scheme, then the entire system is down."

Local racks provide a one-stop location for troubleshooting vs. having to open junction boxes and cabinets that aren't always mounted in an easily accessible spot, says Wade Peterson, electrical engineer, CMD ( in Appleton, Wisconsin. "However," he cautions, "local racks have significant problems when they outgrow their original cabinets. These same issues are trivial with distributed I/O. It's easy to add a new junction box with 10 blocks of I/O and a new node on the network."

Because of the in-depth analysis and diagnostics value of data in a distributed I/O structure, the whole push toward green technology is on the horizon, says Jim Braun, vice president of product development and standardization for MAG Americas ( in Hebron, Kentucky. "If you look at the machine tool industry as a big consumer of electricity, most people want to make parts faster, and that consumes more power," he explains. "In the future, we envision ways of being able to monitor that power and potentially give guidance to the customer about what he might want to do from an energy conservation point of view."

Fuse the Circuit
WTB2-FB130L IEC fuse holder terminal blocks have a current rating up to 30 A, and accept ¼ x 1¼ in. fuses. They have a built-in LED circuit to indicate when the fuse blows and funneled wiring entry with finger-safe IP20 terminals. Marking system allows for fast and easy circuit identification. c3controls724/

Push It
Modular push-in terminal (PIT) blocks reduce insertion forces compared with other spring-technology products. With a 2.5 mm2 cross section, an orange actuation button opens the spring to maximum wiring space of 14 AWG, and the devices are compatible with standardized push-in bridging, marking and testing accessories for all connection technologies.
Phoenix Contact

Four R Series I/O modules for the PXI platform are equipped with Xilinx Virtex-5 field programmable gate arrays (FPGAs). PXI-7841R, PXI-7842R, PXI-7851R and PXI-7852R modules have eight analog inputs, eight analog outputs and 96 digital I/O lines, as well as analog input rates more than 3.5 times faster than previously released R Series devices. These modules provide engineers with commercial off-the-shelf hardware that can be graphically programmed with the LabView FPGA module to perform custom onboard processing for in-line data analysis and deterministic I/O control for applications that require specialized timing and triggering.
National Instruments

Decentralize the I/O
With IP67 protection, X67 I/O modules can be installed on the machine, and can span 100 m between modules. Users can set parameters for the digital inputs and outputs and connect to all standard fieldbuses.
B&R Industrial Automation

Motion I/O
Universal I/O module for multi-axis RMC150 motion controllers has two analog inputs, six discrete I/O and two high-speed Quadrature/SSI channels. The 16-bit analog inputs can be used for pressure/force control or as position or velocity reference inputs. Quadrature/SSI channels can be configured as ½-axis quadrature or SSI reference inputs for gearing or to synchronize multiple controllers.
Delta Computer Systems

Module Finds Trouble
With KE-style enclosure-mount, four input/four output, AS-Interface I/O modules, should an output wire be disconnected, switchable lead breakage detection automatically sends the peripheral fault signal to the upper level controller. Any input pulse/noise spike less than 2 ms is automatically filtered out by input pulse suppression. Advanced diagnostic LEDs alert the user to reverse polarity, overload or short circuit conditions.

Modbus Supporter
APAX-5070 Modbus/TCP Remote I/O coupler module allows a PC, controller or HMI device that supports Modbus/TCP to add remote I/O functionality. The module has two RJ-45 ports with the same IP address, which can build daisy chains to connect remote I/O devices directly without an additional Ethernet switch. It can perform alarms without a controller, with the help of a utility to control the output module based on input conditions.
Advantech Industrial Automation

D-Sub Interface
DSUB DIN-rail-mounted interface modules provide a reliable plug-and-play interface for any industrial control system. CE-compliant modules come with male and female D-subminiature connectors and are available as 9-, 15- and 25-pin models. Optional D-Sub cables are available. Suitable for packaging and automated assembly.
Omega Engineering

Digital I/O Handbook
The Digital I/O Handbook covers a range of devices including optically isolated inputs, relays and sensors, and has circuit diagrams and drawings, and software code examples. Learn about real-world implementation from technical author Jon Titus and company president and CEO Tom O'Hanlan. Enter promotional code CD001.
Sealevel Systems

Spring and Jump
HMM.1 din-rail-mounted spring clamp terminal blocks are 4.2 mm wide and accept PTC jumpers that provide for connecting adjoining blocks together or alternating terminal blocks. The wire range is 24-14 AWG, current rating of 17.5 A at 500 V. HMM.1 has all international approvals including cURus.

Built-In Meter
EL3681 and KL3681 terminals integrate digital multimeters directly into I/O nodes and provide precise, simple, high-resistance measurement from 300 mV to 300 V. Measured values can be processed directly in the I/O system or by the master controller. Immunity to interference is achieved by galvanic isolation of the electronic measuring system and a measurement interval of 200 ms.
Beckhoff Automation

Dinnerctor Line
DINnector line of terminal blocks includes circuit breaker terminal blocks available in ¼ A to 10 A sizes. Terminal block sockets in 12 V and 24 V come with or without LED indicators, and offer single- and double-level plug-in style.


I/O Complete
1799-ER DIO board has dual EtherNet/IP ports, redundant wiring and a built-in managed switch. Universal inputs and user-selectable outputs maximize I/O channel use. The board automatically detects an expansion module connection and provides the necessary EDS files embedded within it.
Rockwell Automation

FAS20 IP20-rated, in-the-cabinet, block I/O stations for AS-interface (AS-i) networks have four inputs or four inputs and four outputs. All ports are terminal blocks in removable and non-removable versions. AS-i bus and AUX power connections can be made via terminal blocks or an optional integrated M12 eurofast bulkhead receptacle for connection outside an enclosure.

Fail-Safe I/O
ET 200M fail-safe modules for Simatic ET 200M I/O station meet requirements of SIL 3/Cat. 4 and PL e in mixed operation with standard modules, without a safety protector. The modules have Profisafe-Profil 2.0 for use in Profinet networks in connection with PN/DP couplers. Modules can send an acknowledgement after a voltage drop and preserve the last valid function, which provides the last valid state, and energize-to-trip functions to provide the last value.
Siemens Industry

64 Channels
Analog input modules for EtherStax provide high-resolution scanning of 64 single-ended channels monitoring dc current or voltage signals. ES2163 and ES2164 models perform 16-bit A/D conversion and interface to Ethernet devices or controllers with Modbus TCP/IP or UDP/IP. Scanning updates all 64 channels in less than 10 ms. ES2163 accepts dc current with ±20, 0-20 or 4-20 mA ranges. ES2164 units accept ±5 or ±10 V.

Combo Block
Series 2020 and 2022 X-Com S pluggable connector systems merge touchproof, pre-wired assemblies with TopJob S terminal blocks to combine pluggable connectors, DIN-rail blocks and Cage-Clamp S connection to streamline and eliminate wiring errors during panel and machine building. The terminal blocks are available in single- or double-deck configurations and 3.5 or 5.2 mm pin spacing.

Compact Size
Impact20 fieldbus I/O station is designed for applications in terminal boxes and control panels due to its compact size. It is available for CANopen and DeviceNet protocols and as a 16 output only, 16 input only or mixed with eight inputs and eight outputs.

Advantys STB IP20, bit-modular, distributed I/O platform provides 512 I/O points per island, with up to 32 modules per island on seven segments. Configuration software includes I/O diagnostics, and the platform has hot-swap capability and removable memory cards. Up to 16 I/Os and eight networks can be supported.
Schneider Electric

Master Distributor
microNCS provides Modbus RTU (RS-485) master capabilities, cost-effective distributed data acquisition and, with expansion I/O, control capabilities. One or both of the microNCS's Modbus RTU ports can be configured to poll other RTU slaves with all of the network polling functions of a typical Modbus master. An industry-standard OPC interface delivers plug-and-play integration with popular PC-based HMI and SCADA software packages.
Moore Industries

Dense-Packed I/O
Eurostyle terminal blocks have front-style plugs with a wire-entry cavity and activating screw head located on the same plane, parallel to the direction of the plug, which allows the plugs to be densely stacked, side by side. Offered in 5.0 and 5.08 mm centerline spacings, the blocks have a current rating of 300 V and 16 A, are available with 2-12 positions, and accommodate 14-24 AWG wires.
Tyco Electronics

Analog I/O Backpanels
Analog I/O signal channels provide each 8B module with an analog bus, and all module outputs are simultaneously accessible to high-speed data acquisition boards. A temperature sensor provides cold junction compensation for thermocouple input modules. It has a -40 to 85 °C operating range, and high-density screw clamp, 16 AWG max, interface connector.

Can Two
CANopen extension module 1 SI for Simatic ET200S I/O system connects CAN 2.0A and CANopen devices with the integration of the CAN 2.0A protocol. The module can be used for transmission/reception of any CAN 2.0A frame regardless of the overlaying CAN application protocol. The module can be engineered with Step7, and allows upgrading already-existing 1 SI CANopen boards with this new functionality.
HMS Industrial Networks

125 Vdc input module for the RX3i controller provides 16 input points in one group with a common power input terminal, one control engine, 300 MHz Intel microprocessor and 10 MB of user memory, a universal backplane with a high-speed PCI bus and a serial bus for simple I/O.
GE Intelligent Platforms

Measurement Module
Snap-AIPM-3 analog input module measures and manages three-phase ac power usage, mounts on an I/O rack and measures Vac rms and Aac rms. The module calculates true power, Volt-Amps and power sums for all three phases of power. When used with Snap controllers or I/O, it can support controlling and regulating equipment and facility power monitoring.
Opto 22