The Campus Guard application
In the present section, it will be presented a brief description of a user interface application targeted to support monitoring building activities, supported by the infrastructure described in the previous section, mainly related with security.
Figure 1 explicitly shows the distribution of processes over an experimental set-up.
The equipment installed in the building and used in this set-up is composed by three low-cost workstations running Microsoft-Windows (PCU, PCS-1 and PCS-2), the institution telephone switch (PABX) and a RS-485 network of three programmable logical controllers (PLC-1 to 3). Sensorial systems include cameras and presence detectors.
The SCADA user interface is referred in Figure 1 as “Campus Guard”, and relies on four servers, namely “Name server”, “PABX server”, “Image server”, and “Sensor server”, which in turn will be connected to low-level controllers through specific communication bridges.
Figure 1 An experimental set-up
Figure 2 User interface of the Campus Guard system
Figure 2 shows a typical monitoring session, where two floors, named “Piso 0” and “Piso 1”, are under monitoring. Two windows associated with two cameras and another one associated with a telephone terminal (extension 231) are also shown.
Hierarchical synoptic
The “Campus Guard” application enables navigation through the campus. In previous section, monitoring of one building was illustrated. The “Campus Guard” application has the geometric information related with the spaces to be monitored (plants of the building). This enables the visualisation of the building plants.
Afterwards, the name server will be contacted by the “Campus Guard” in order to provide information about the devices installed in all of the individualised spaces, namely device identifier and specific server that handle those devices.
In the final step, those specific servers will be contacted to provide information associated with each installed device.
The user interface hierarchical structure of the “Campus Guard” application is presented in Figure 3.
Figure 3 Hierarchically organized synoptic
The user may navigate towards a specific floor and get specific information related with the different devices installed at that floor. In the examples used, three entity types are considered: presence detectors, cameras and telephone terminals.
The presence detectors states are shown through the use of different colours enabling an easy interaction with the user. Possible status of the presence detectors are: “off”, “on”, “active”, “unknown but last information is on”, “unknown but last information is active” and “unknown at all”. The three last status values deal with errors in the communication with the associated programmable controller, due to a lack of connection or any other communication problem.
Telephone terminal and cameras have specific dialogue windows enabling the presentation of specific information. In the case of images, the actual image can be shown. This may substitute with obvious advantages the panoply of monitors commonly present in a CCTV centre.
Web technologies everywhere
Current trends on building monitoring systems emphasize usage of web based technologies. As a matter of fact, remote access (either through the telephone line, as in the old days, or through the internet, as nowadays) to home and building appliances has been always referred in the literature as one main feature associated with the concepts of intelligent home and intelligent buildings.
Heavy introduction of web technologies everywhere can be seen as an expected step, in the sense that we can benefit from:
- Unlimited access points, as far as any computer connected to the internet can have access to the system (licenses is here a delicate issue);
- Uniform way to use applications, which means that it is not needed special training to get acquainted with the way to have access to the system.
Current commercial applications targeted for building monitoring and supervision can be roughly divided into two main groups:
- Proprietary applications, relying on proprietary protocols or
- Applications emphasizing open system concept.
Here, we give special attention to the second group of applications, which have the following main (desirable) features:
- Extensive support for web technologies, which means that a common browser could be used as user interface;
- Support for portable computing, namely handheld and wireless PCs;
- Support for WAP operation;
- Default connectivity capabilities to main standardized protocols used in buildings, namely BACnet, LonWorks, MODBUS, or EIB;
- Multi operating system support (including Windows, Linux and others);
- Compatibility with several data base management systems (from SQL to JDBC);
- Easy connectivity with external applications (for instance, to allow convenient alarm handling or launching of external procedures).