Maintenance Resources has a wealth of information contained in archives back to February of 1999. This is the e-zine for plant engineering, maintenance and reliability professionals. They also offer an emailed version, to subscribe click here . Also be sure to check out their 24 categories in the Reference Library . Select from hundreds of helpful how-to articles, glossaries and more all available for your use at no charge.
Articles are more on the management and high tech side.
Try their search engine, a search for PLC brought up 81,878 articles. Strong on content, looks good too. There's a trouble shooting database, last we checked database slow and only a couple entries. The world's leading magazine and information source for site and facility planning simplifies the important criteria required for making new industrial and corporate facility decisions. Whether you are in management or just want find information to support discussions with management, this site is packed with information.