Every month, Controls editors take a specific product area, collect all the latest, significant tools we can find, and present them here to make your job easier. If you know of any tools and resources we didn't include, send them to firstname.lastname@example.org, and we'll add them to the website.
PACs FOR COMMUNICATIONS AND DATA HANDLING
Many process control applications require much more than just real-time control, and extensive communications and data handling can tax the functionality of PLCs. In these instances, a programmable automation controller (PAC) can be a good fit. Most PACs are derived from the PC world, hence, their relative strength when it comes to communications and data handling. Control's senior technical editor, Dan Hebert explores some PAC basics. Go to www.controlglobal.com/articles/2008/026.html for his insights.
PLCs, PACs AND POWER OVER ETHERNET
Field level wiring used to be very simple. A sensor was either powered or passive. But, when networking PLCs and PACs coming into the control system network became both practical and popular, engineers started thinking about how to provide power over the same set of wires as the network connection. This white paper discusses how Power over the Ethernet is fast becoming the standard. The link to the free registration page is http://tinyurl.com/47mvsqm.
DESIGNING PLC MODULES
This webcast deals with the requirements and challenges associated with the design and implementation of analog input/output modules used in industrial control applications, with a particular focus on programmable logic controller (PLC) modules. Design and applications tips and techniques will be presented, and examples of Analog Devices' solutions will be discussed. A direct link to the webcast is at http://tinyurl.com/4kg28z8.
GUIDE TO PLCS AND OTHER DEVICES
This link-rich page provides the user with basics for determining whether you need a programmable logic device, tips for finding training, and lists of available sources. A direct link to the pages is at http://tinyurl.com/4jlodm5.
This site contains dozens of downloadable PDFs on a variety of PLC and PAC subjects, including "Understanding PACs," "A Controller System for Industrial Automation," "The Design of a Portable Programmable Logic Controller," "Introduction to Programmable Logic Control," "Logic Control Systems" and "Embedded and Industrial Automation." Each selection offers both a full download and a preview page to aid in selection. The direct link is at http://tinyurl.com/4sqatud.
HOW TO RECONFIGURE A CONTROLLER
Process control expert F. Greg Shinskey discusses the power of external-reset feedback in this article from Control magazine. He says that preventing windup requires reconfiguration of the controller, and external-reset feedback is the most satisfactory method of accomplishing it. The article includes techniques and equations for this process. The direct link is at http://tinyurl.com/4lwngsg.
The PLC Tutor
If you have the desire to learn about programmable logic controllers and/or programmable automation controllers, or if you need a refresher or some tutoring, then this is the place to go. Chapters include coverage of I/O wiring and interactions, number systems, memory structure, bit instruction, timers and counters. There is also a list of external links to more resources.
PLC/PAC EBOOK SHELF
This site holds a collection of ladder logic and PLC/PAC tutorials from a variety of sources. All are free, although registration is required. The site contains links to white papers, tutorials, ladder logic diagrams, simulations and more. Documents come in .doc, .docx, PDF, .rtf, .xls, .ppt, .pptx and .pps formats. The direct link is at http://tinyurl.com/4b7ltzz.