At its most basic, a switch acts in a binary fashion, changing state when a pressure, temperature, level or other process variable crosses over some predefined threshold. If the process variable in question can be allowed to vary in the course of normal operation, a simple mechanical switch linked to an on/off valve or pump can effectively and reliably control the process at hand, keeping a tank from running dry or a temperature from climbing too high.

Transmitters, on the other hand, continuously measure and communicate their assigned process variables over a range of values. A transmitter can facilitate on/off control actions similar to those of a switch through configurable discrete outputs within an associated controller. But a continuous transmitter teamed with a modulating control valve or pump with variable speed drive also can be used to implement more subtle (albeit more expensive) control strategies -- such as a proportional‐integral‐derivative (PID) algorithm ‐‐ to maintain the process variable at a specific value or setpoint.

A third option is the integrated or hybrid switch‐transmitter, which combines a continuous transmitter and solid‐state switch within a single instrument housing. This approach effectively combines a number of the advantages of both.

RTDs determine changes in the electrical resistance of materials in relation to temperature. RTDs deliver very precise readings (typically to 2–3 decimal places) and are manufactured in a variety of form factors. Though they are sometimes composed of nickel, copper, or other metals, historically, RTDs have been made of platinum--largely due to the fact that platinum's resistance-temperature relationship is maintained in a very linear fashion across very broad temperature ranges. RTDs' platinum composition also makes them somewhat expensive and unsuitable for applications involving temperatures above 660 °C, as temperatures above this range compromise the inertness of the platinum and may cause it to become contaminated and deliver inaccurate readings.

This white paper describes various temperature sensors such as RTDs, thermocouples, ICTDs, thermistors, and infrared sensors, and the Opto 22 solutions for using them.

However, its practical implementation faces a number of challenges: not least the present lack of a universally agreed standard. This white paper looks at some of these challenges and presents the approach being taken by Yokogawa.

In order to understand the ways in which wireless technology can aid the implementation of industrial automation systems, it is first important to clarify what is meant by the word 'wireless' in this context.

Download this white paper to learn more.

Security measures aim at protecting the confidentiality, integrity, and availability of a computer system from being compromised through deliberate or accidental attacks. Similar to process and safety improvements, security improvement needs to be a continuous activity.

This white paper provides background and a general overview of different elements of information system security, with specific emphasis on how it applies to industrial automation and process control. Different security measures that should be considered when an automation system is connected to external networks of different kinds are discussed, including connections to general purpose IS and corporate networks, remote connections, and wireless connections.

Cleaning produced water costs 300 times more than cleaning municipal waste water and 3,000 times more than cleaning irrigation water. Since each water treatment system can vary based on the water quality and the environmental regulations for its reuse, there is no universal treatment process. Nevertheless, basic requirements must be met when dealing with produced water.

It is important for companies to understand these factors so that oil and gas production can be maximized while containing costs and complying with regulations.

This white paper from Endress+Hauser explains where produced water comes from, how it is treated, and the instrumentation needed at every stage of the process.

The installed base of fieldbus devices and indeed all intelligent field devices continues to grow significantly. As any experienced user will tell you, however, intelligent devices can pose an information management problem, especially when you have devices on different networks with different underlying technologies for displaying and managing information.

Historically, the two primary technologies used for presenting and managing information from intelligent devices are FDT and EDDL. Both technologies are complimentary in some ways and overlap in other ways. Many in the industry felt that rationalizing the two technologies to form a single solution would be a good idea, particularly since all the major suppliers support both FDT and EDDL technology. This was how the Field Device Integration (FDI) project was born.

FDI activities continued, but were somewhat sporadic, until 2011, when all of the five major technology foundations, including FDT Group, HART Communication Foundation, OPC Foundation, Profibus International and Fieldbus Foundation signed an agreement to form FDI Cooperation LLC, a company dedicated to seeing through the development of the FDI specification its associated development  tools, and product testing and registration.
The real goal of FDI is to make life easier for the end user. FDI promises a common set of development tools and a single path to managing the flood of information from intelligent devices across different networks to the applications and ultimately the people that need it. It offers standardization, transparency, and, ultimately, reduced cost. The Fieldbus Foundation is committed to the long-term success of FDI.

The paper presents the results of an extensive study involving up to four environmental chambers and more than 1,000 actuator samples to develop a grid of 13 humidity and temperature conditions. Weibull-analysis is used at every condition to determine the DC-voltage dependent lifetime of the co-fired PICMA multilayer actuators. In addition to the (most critical for precision positioning applications) DC tests, behavior under large-signal AC-conditions with up to 10¹⁰ cycles for different functions as well as temperature-conditions was also evaluated. Three patented design features of the latest actuator generation are based on the findings.

Selecting the right one for the right job is not necessarily an easy feat. Whether a particular pressure sensor is suitable for a specific application will depend in great part on the sensor's attributes, the environment it's being specified for, and the job it's being asked to perform.

So, how do you select sensors that address multiple customer-specific performance requirements? Here is a guide to finding just what you're looking for based on your performance requirements or design needs.

The authors in this document suggest a policy-based approach that instead sets clear guidelines for asset owners, starting with regulations for new critical infrastructure facilities, and thereby avoids perpetuating the problem in systems and architectures that will be around for decades to come. In contrast to the IT sector, the industrial control systems (ICS) that keep the nation's most critical systems running are much simpler and much less dynamic than contemporary IT systems, which makes eliminating cyber vulnerabilities, most of which are designed into products and system architectures, actually possible. Finally, they argue that a distinction between critical and non-critical systems is a bad idea that contradicts pervasiveness and sustainability of any effort to arrive at robust and well-protected systems.

Register to download this document and learn more. We'd love to have your reaction to what you've read (either positive or negative). After reading the document come back and tell us what you think.

Read what our community experts have to say:

• Can We Use Risk Analysis to Determine the Economics of Cybersecurity?
  By Walt Boyes, editor in chief
• Cybersecurity Responsibility White Paper
  By Joe Weiss, cybersecurity expert and blogger
• Is Field-Based Control More Secure?
  By John Rezabek, proces control specialist

Flow control is one of the most critical functionalities in the hydraulic industry. Traditionally, flow control is implemented via a proportional or servo valve. The principle of proportional and servo valves is briefly reviewed in the following. When current is applied into the coil of a solenoid (proportional valve) or a torque motor (servo valve), a corresponding electromagnetic force is generated. These forces could either directly stroke the spool (single stage configuration) or indirectly move the main stage spool via regulating the hydraulic pressures on the each end of the main stage spool (multiple stage configuration). The motion of the main stage spool leads to the variation of the orifice area. With a given pressure drop, the orifice area is directly associated with the flow rate. Modeling and control of proportional and servo valves is very rich in literature /Mer67/Jel03/Eat99/. However, most proportional and servo valves on the market are incapable of providing accurate flow rate control without feedback from the power elements or without the addition of mechanical pressure compensators. For example, consider a double-ended hydraulic cylinder with the piston area equal to 1 [unit]. If the required speed is 1 [unit], then the required flow rate is actually 1 [unit]. Without knowing the displacement/speed information from the hydraulic cylinder, neither the servo valve nor the proportional valve can correctly provide the desired flow. The reason for this is because the flow rate is related not only to the spool displacement (orifice area) but also to the pressure drop across the orifice. Therefore, feedback from the power elements is often required to achieve accurate flow control.

Visit Eaton's webpage to download this white paper.

Download now

Once Automation devices and the computers used to program them share a topology model and communications protocol similar to PC’s, (TCP/IP), concerns arise over accessibility from unauthorized parties. Methods of security can range from technologies based within the infrastructure itself such as physical connection paths and virtual LAN’s to hardware/software based devices such as firewalls and security management servers. A comprehensive Security Plan exists for both internal and external protection. Preserving the integrity of the network by preventing unwanted traffic from unauthorized sources, securing the programming logic and preventing intrusion are essential elements of such a plan. With a secure network, engineers can then reap the benefits of access to devices for programming, service or information.

This paper will discuss how you can leverage lean operations, a lean supply chain and lean design of your electrical panels to meet the key goals from James P. Womack and Daniel T. Jones' book Lean Thinking:

• Determine what the customer is willing to pay for...this is value.
• Identify the processes required to provide value...this is the value stream.
• Physically arrange the required resources in a "flow."
• Implement "pull systems."
• Eliminate waste from the flow.

Although a lot of alarm management projects start and fail due to poor understanding of the scope of the probelm, lack of resources or money, loss of momentum, and no identifiable return on investment, the real key to success is to establish responsibility.

Why deal with accuracy?

The reasons for dealing with flowmeter accuracy specifications are many-folded. One important reason is from an economical point of view. The more accurate a flowmeter can measure, the more money you will save as the medium is measured with only very little inaccurately.

Another reason is in terms of dosing, where a given amount of a medium is added. This must be done with a high level of precision and the accuracy is thus important in order to dose correctly. This is critical in certain industries such as in pharma or chemical.

A third reason is in terms of billing purposes. By performing with good accuracy, you know exactly how much fluid flows into the process. Thereby, you are able to determine the right price of the product and thereby bill the customers correctly.

Therefore, knowing how much that flows through your system is paramount in order to make a profitable and solid business. You need to rely on a precise measurement with good accuracy. However, good accuracy must be obtained not only in one measurement, but in all measurements independent of the time.

For machine builders there is a great demand to increase the productivity and flexibility of their machines, while maintaining healthy margins. This can be a difficult balancing act between using the most effective technology while working within a shrinking budget. Distributed I/O systems connected to an industrial network allow for I/O data to be spread across the machine and outside of the cabinet; reducing the total component and hardware costs of the system. New developments in distributed I/O technology have lowered the cost per point of the controls design and have reduced the time to integrate.

The focus of this whitepaper is to inform controls engineers working for machine builders about the advantages of distributed modular I/O on an industrial network and how to select the best out-of-the-cabinet controls solution for manufacturing equipment.

Read this white paper now.