Since the publication of the first edition in 1992, the HVAC industry has gone through enormous changes. As simple digital systems have given way to more complex systems, demand for information on how these systems operate, how they are best applied and how they communicate with other building control systems has grown rapidly. Direct Digital Control for Building Systems, Second Edition is thoroughly updated and expanded to include coverage of the architecture of modern digital control systems, distributed intelligence networked systems, communication protocols, the technologies and issues concerning interoperability, the latest application strategies, and defensive techniques for designing and specifying control systems.Numerous illustrations throughout help keep the subject highly accessible, and hardware, software, and systems applications are described in the most universal terms possible. This thoroughly revised second edition also contains a full section on BACnet standard and Echelon's LonWorks technology their meaning, applications, and future implications. An up-to-date appendix is provided. Insights on emerging technologies in intelligent control systems and what the future holds for this dynamic field is covered throughout.