DDC网络用LonWorks还是BACnet... The intent here is to answer that question with a simpler question "What are you trying to accomplish, and does one protocol, or more specifically control and network products based upon it, provide a better solution than the other? One of the most challenging decisions facing the controls industry today is what Building System Network should be the standard for future systems. The debate is heated between supporters of these networks, or communication protocols. Making the decision, BACnet?or LonWorks? is tough but is it really necessary to choose one over the other? The intent here is to answer that question with a simpler question "What are you trying to accomplish, and does one protocol, or more specifically control and network products based upon it, provide a better solution than the other? The DDC industry has been inundated with information on communication protocols, and vendors are selling complete automation systems, as well as individual components, and recommending standardization on one Network or the other. Considering the impact of networks on a DDC system, it is becoming necessary to understand not only controls and HVAC, but computer networking and information technology. In spite of that added demand, real benefits are available, as the evolution of DDC Network standards presents the opportunity to achieve open systems, and to leverage off the shelf technology and the worldwide web. The basic requirement for making system communication protocol decisions is the same as ever: clearly define your expectations. By 1995 when ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) published BACnet? there were 100 or more networks and communication protocols in use throughout the controls industry. Multiple DDC Manufacturers with multiple generations of products contributed a proliferation of system networks based on countless proprietary protocols, commonly referred to today as "legacy systems". System users had long voiced concerns about the complexity of DDC system management and expansion. This was due to the inability of systems to share data or communication networks. The industry became aware of the role that communication played in the long-term success of DDC systems and the importance of protocols and networking. The same challenges remain today, but with a tremendous simplification, rather than 100 protocols there are only two, and for now it is simpler to call them both standards. Both BACnet?and LonWorks?are standards of one type or another, but that doesnt make the choice easier. If one counts legacy systems still in use, there are more than two networks but it is easier to integrate them than ever before, and theres less resistance to making legacy source code available to simplify the task. In the final analysis, establishing system requirements and choosing between communication options comes down to defining one requirement; interoperability. Focusing on interoperability may appear to sidestep numerous issues being debated in the Network "camps". The fervor that supporters of each Network demonstrate, and characteristics that are touted for each makes this issue seem immensely complicated. Set aside however, questions of who controls the standard, what type of standard it is and the level at which it operates? Certainly these are important questions, but the larger concern remains how will the control system be applied, and what level of interoperability is required? Interoperability in some respects is an overused and under-defined term. Therefore the focus here will be on defining interoperability and pointing out how it can be instrumental in determining system success or failure. Interoperability can be viewed as a continuum with levels as illustrated below. At the most basic level, interoperability is about communication. The two issues that drove standard system communication were the ability to share data and the ab