I/O Systems Resource Center

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Controls engineers, and that includes industrial machine controls, need a variety of information on device connectivity via their input/output, I/O modules and components on topics such as terminal blocks, remote I/O devices, distributed I/O devices and sensor networks, signal conditioning, cabling, wiring, connectors and cordsets.

Terminal blocks, available as spring clamp terminal blocks, screw clamp terminal blocks, and newer insulation displacement terminal blocks (IDC) are the most popular choices.

A type of industrial I/O modules known as Remote I/O provides an ability to distribute control closer to the components and share the overall control responsibilities. These modules are frequently called Distributed I/O or industrial distributed I/O.

Industrial Machine mount I/O, a sub group of remote I/O, is growing is popularity as it provides flexibility and faster reconfiguration with reliable connection using connectors and cordsets, while avoing the costs of protecting the industrial I/O within panels and cabinets.

As machine data becomes more critical to overall operations, signal conditioners and other signal conditioning devices increase in importance by helping ensure data signals are clean and uncorrupted.

The growing use of industrial digital networks, particularly starting with sensor-level networks and device-level networks, provides faster, less expensive, easier to maintain and troubleshoot data transmission.

Timely news, back-to-basics primers, feature articles, technical white papers and descriptions of the latest products all provide valuable insights that can be used in designing and building machine controls.

All the Right Connections
Gateways and Protocol Adapters Help Users Resolve an Ever-Growing List of Network Options

Digital Network Reliability
How Can You Increase Reliability and Network Availability?

Reasons to be Modular--or Not
Considering the Pros and Cons as They Relate to Your Machine and Its Users

Modular Machine Building Succeeds in Sections
Modular Machines and Production Lines Enable Quick Disconnects and Speedy Changeovers. This Flexible Approach Inspires Builders to Combine Modular Equipment in Ever More Innovative Ways

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White Papers: In Depth Research

Expanding Allen-Bradley PLC Systems With Intelligent Remote I/O
Author: Opto22
Posted: 12/20/2011
Allen-Bradley ControlLogix, CompactLogix, and similar control systems have become a corporate standard for many companies. As a control engineer, you are familiar with these systems and their architecture. You appreciate their strengths and understand how to best utilize them. And you're well aware that every expansion of the PLC system, whether into new physical space or into new functionality, by necessity puts a strain on system performance.

This PLC expansion dilemma you face with each system change is more and more frequently tied to new demands on automation functionality. Today's more sophisticated automation applications often require more than the traditional scan inputs-solve logic-write to outputs approach. Incorporating connections to third-party devices, such as RFID and barcode readers, and involving more complex logic such as PID (proportional-integral-derivative) control loops, these applications place heavy, nontraditional demands on PLCs.

Of course any expansion of a PLC system means the addition of I/O for new sensors and actuators. The PLC must scan the new I/O and run logic for it, which impacts processing power. But in comparison to existing I/O, the new sensors and actuators may demand proportionally more processing power because they are simply a different type of I/O.

Analog is a good example. Applications using many analog inputs and outputs require temperature conversion, thermocouple linearization, analog scaling and Engineering Unit conversion. All these new functional demands place nontraditional burdens on the central controller.

As functional demands for industrial automation systems increase even while budgets shrink, you may be wondering if there are other ways to achieve system expansion.

Signal Isolators, Converters and Interfaces: The Ins and Outs
Author: Moore Industries
Posted: 11/19/2010

The ability to depend on accurate monitoring and control signals is absolutely priceless. Inaccuracies can lead to process inefficiencies, process upsets and even very costly plant shutdowns. Much worse, inaccuracies can lead to dangerous safety conditions for plant personnel. Whether you call them signal isolators, signal converters or signal interfaces, these versatile workhorses are indispensable tools that enhance measurement accuracy and protect signals from damaging conditions, thereby saving time, resources and money.

With the extensive array of isolators available, selecting the correct isolator or the right combination of isolator features can be a bit daunting. However, if you take the time to add the right instruments to your process, signal isolators, converters and interfaces can help improve the efficiency and throughput of your process.

This guide by Moore Industries will tell you many of the important ways signal isolators, converters and interfaces can be used, and what to look for when deciding which one is the right solution for you.

Redundancy in Technological Systems
Author: Helge Hornis, Ph D, Manager, Intelligent Systems, Pepperl+Fuchs
Posted: 03/10/2010
Redundancy is a concept frequently applied in technological systems. When investigating in detail why redundancy is used, one will find that there are many reasons for doing this. Looking at several redundant implementations should make this clear. Still, all aspects of redundancy have one idea in common: increased ability to control a system even when problems occur.

Functional safety systems are probably the most common automation solutions based on redundancy. Here the rationale is to provide a control system that is able to safely shut down a machine in case of emergency. Depending on a detailed safety evaluation, safety solutions of varying complexity can be used to address the particular needs of the application. Safety systems are still designed to comply with EN954, which divides applications into five classes between B at the low end and CAT 4 at the upper end. To show that not all redundant systems are equal, let's focus on two scenarios. Figure 1 shows a safety system where a number of redundant-safe input devices (e-stops and magnetic interlock switches) are connected redundantly in a series. These safety strings are then connected to a safety relay, which is ultimately responsible to shut down motors, drives or other potentially harmful devices. Consider a situation where one of the safe contacts on a magnetic safety switch is welded or simply sticky. Due to the redundant nature of the safety string, the machine will still come to a safe shutdown as soon as the door, evaluated by this magnet, is opened. Even better, the safety relay will not even allow a restart of the system after the door has been closed. The reason for this is that the safety relay demands that as soon as one of its safe inputs shows an open contact, the second input must also go open, clearly a condition not satisfied due to the welded contact. Unfortunately, it is rather trivial to trick the safety relay. All one has to do is open and close another door. As soon as this happens, the safety relay detects its two inputs as open, making this a resettable condition. As soon as this happens, the redundant nature of the system is compromised. All it takes is a second fault at the magnetic door switch, and it will not be able to result in safe system shutdown.

TIA-1005 Industrial Ethernet Cabling Standard
Author: Anixter
Posted: 10/28/2009
The Effect on the 10/100 Industrial Ethernet Switch Performance.

The Anixter Infrastructure Solutions Lab wanted to determine what effect the new TIA-1005 industrial cabling infrastructure standard would have on the data throughput performance of real Ethernet data packets running between SmartBits test cards and various manufacturers' 10/100 Ethernet switches in a real-world simulation. The test included five (5) different IP20-rated switches and three (3) different enterprise rack-mounted switches using various cabling channels made from both Category 5e and Category 6 cabling components and connector pairs that are allowable under the standard. The premise also asserts that the effect of the cabling channel interference will also vary from port to port and switch to switch because of the variable transmitter and receiver functionality.

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