A low-cost internet connection for intelligent appliances of buildings

To date, the Internet has been a network connecting mostly desktop PCs, but soon all kinds of intelligent devices containing a small microprocessor will exchange data over the Internet. This will have a big impact on buildings and their technical systems, which now include a number of processor-based devices. Internet connectivity implies a totally new way to control and manage these devices. The potential benefits will be significant. Therefore, the need to design low-cost Internet appliances is worldwide today, and many commercial products are already available. This paper proposes a new technical approach to connect small processor devices to the Internet. The approach makes possible a connection both through the Public Switched Telephone Network (PSTN) and the Global Systems for Mobile Communications (GSM) network. The connection is based on networking software programmed in the processor device and a gateway server, which together transfer data between the PSTN and other communication networks. The data communication utilizes the Short Message Service (SMS) and the Extended Machine Interface (EMI) protocol. Besides the low cost, the proposed system has several benefits, such as uncomplicated structure and operation, standardized data transfer, and an ability to be embedded in an 8-bit processor device. Yet, the approach does not require high-speed data communication. Thus, it is especially suitable for applications controlling slow and non-critical building processes. The proposed system was demonstrated by designing a microprocessor device interfaced to an Air Handling Unit (AHU). Sensor data from the AHU was transferred to the Internet through the PSTN and the GSM networks. In addition, a Web-user interface was created for the remote control of the AHU. The results of the pilot project were encouraging and will be used as a basis for further development of the system.