1984). One of the most challenging house industry the number of high- Real-time tasks of the modern greenhouse grower tech greenhouse operations is con- Monitoring of is to manage the large amount of data stantly increasing. It is becoming volume and to process it in such a way increasingly important to monitor the Greenhouse that important information is not over- system 24 h per day by a wider range of looked because of an overload of the people who have an interest in the Climate Control available data (Ehler and Rystedt, information. In university greenhouse 1990). This makes information man- operations, researchers and students Using the agement an important area of research alike are interested in closely following and development in greenhouse envi- the experiments, but without having Internet ronmental control. Once the signifi- to be physically present all the time. cant information has been identified Furthermore, the general public might and retrieved, it may be necessary to also have an interest in climatic infor- Niels Ehler and provide a broad range of users a simple mation, not just from inside the green- Jesper M. Aaslyng way of accessing these data. The Inter- houses but also from the weather net is an obvious candidate as a chan- station connected to the climate com- nel for distributing this information. puter system and from ongoing re- So far data access for greenhouse com- search. ADDITIONAL INDEX WORDS. environmen- puters has only been possible using The objective of the project was tal control computer, HTML, remote access software packages, but to develop a system that could dy- databases, dynamical web integration this requires installing of licensed soft- namically generate a web application SUMMARY. The possibility of con- ware on both the client and the server to integrate real-time greenhouse con- structing an Internet application that PC. trol information. The web site should would enable greenhouse users to If greenhouse information can be work reliably to supply greenhouse track climate and control parameters directed to a web site, then any person, users with continuous climatic infor- from any Internet-connected com- regardless of having special technical mation. The site should enable the puter was investigated. By construct- skills, can gain access with a standard user to quickly gain access to the most ing a set of HTML-templates, Internet browser. The greenhouse is a critical data describing the greenhouse dynamic information from the dynamic system where important sys- climate and the status of the control control-system databases was inte- tem states change every few minutes. functions. Furthermore, the applica- grated in real-time, and was uploaded to a common net-server by automatic Therefore it is necessary that the con- tion should be readily tailored to suit generation of web pages using tents of the web site should be auto- software developed during the project. matically updated on a similar Fig. 1. Outline of the total system Good performance, reliability and time-scale, to provide the user with the structure showing the different security were obtained and the current climate and status of the tech- system components and how they technology proved to be an efficient nical systems. In the European green- relate to each other. way of supplying a broad range of users not only with climatic data but also with results from ongoing research.
reenhouse climate con- trol traditionally has been G a topic where process regula- tion has been the main focus. The introduction of computers and digital technology in the early 1980s has greatly improved the control possibili- ties and significantly increased the amount of data acquired by standard greenhouse operations (Hashimoto et al., 1980; Udink ten Cate and Challa,
Section for Horticulture, Department of Agricultural Sciences, The Royal Veterinary and Agricultural Uni- versity, Thorvaldsensvej 57, DK 1871 Frederiksberg C, Denmark. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact. The authors thank Allan Holm Nielsen for his invalu- able assistance in designing the graphical elements integrated in the web application described in this paper.
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Microsoft Windows information. This was done by send- 95 operating system ing a request to BipsArch, the green- and the DGT- house server program to begin Volmatic ECC-stan- collecting the data from the climate dard software computer system needed by the web Superlink (DGT- application. Volmatic, 1988). The web-application program Superlink included a (CYBGR4) processed a list of all the standard application web pages needed for the application. interface, described by Each page is represented as a text file Ehler (1991). This containing HTML coding, which func- application interface tioned as a template for the page shown was used for running on the Internet. On a given page cer- a database application tain locations were selected to contain BipsArch, which was the variable information from the developed by the greenhouse compartments. Any ob- project. BipsArch servation is given a specific name in the can connect to any standard database to distinguish it from climate computer any other observation. For instance, system through a the air temperature was assigned the well-defined, ven- identifier name TmpAir. The system dor-specific device then scans the database for the given driver, which re- combination of compartment number flects the structure and input name and retrieves the de- of the used climate sired record that contains all the data computer system. for the given observation, such as the BipsArch continu- observation value and the time and the ally updates a set of date, when the observation was per- Paradox databases formed. (Borland Interna- CYBGR4 parsed the text file and tional, 1992) with converted the values into standard- greenhouse infor- HTML code which can be shown by mation every 10 any browser. The new HTML file with min, effectively cre- the dynamic data was then written to ating a virtual green- the local disk. When all the new pages house. These had been generated, they were up- databases serve as a loaded to the university’s common Fig. 2. The main welcome screen of shared common and generic informa- web-server. To cater for special infor- the greenhouse web application. tion pool and standard interface for mation that was not part of the normal any greenhouse application that needs environmental computer system, specific information needs arising from, to access climate information or needs CYBGR4 also had the ability to gener- for instance, demands made by ongo- to update the set points of the ECC. ate new information by processing the ing experiments. BipsArch was developed using the typical environmental data, for example Borland Delphi 3.0 (Borland Interna- the maximum temperature of the last Materials and methods tional, 1997) programming language. 24-h period. This was calculated based SYSTEM OVERVIEW. The overall The greenhouse server also ran on the contents of the standard data- structure of the system, which was the web site generation software bases. The result was returned to the implemented at the greenhouse com- (CYBGR4) developed by the project. common database, thus supplying new plex of the Royal Agricultural Univer- CYBGR4 was responsible for generat- information which could be used by sity of Copenhagen is shown in Fig. 1. ing the necessary HTML-pages and other applications running on the Twenty greenhouse compartments uploading them to the university web- greenhouse server. were controlled by an environmental server, using a simple FTP protocol via control computer system (ECC) sup- an Ethernet connection. Results and discussion plied by the DGT-Volmatic A/S Cor- STRUCTURE AND FUNCTION OF STRUCTURE AND CONTENTS OF poration (Brøndby Strand, Denmark). THE WEB-APPLICATION GENERATOR THE WEB APPLICATION. The main struc- This system consists of seven PROGRAM CYBGR4. The main tasks ture consisted of a welcome screen LCC1200-microcomputers (DGT- of this program were to access the (
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T&P 640 9/5/01, 12:01 PM The same data were shown for all com- partments, but new information could readily be added to a given page. All that was needed was to add the relevant BipArch code to the HTML template and if necessary add these data to the greenhouse standard database. This only called for one new line of code in the program. From the compartment page the user could either choose another compartment through the menu but- tons on left side of the screen, or return to the site map by clicking on the picture at the top of the menu. Performance and stability were considered as the highest priority. The web page generation system was located in an integral part of the greenhouse server. This could affect performance as the server needed to run efficiently so that all the other parts of the control systems for the greenhouses were not impaired in any way. The most impor- tant factors affecting performance were the size of the database, access methods for the database, parsing-algorithms for analyzing the HTML templates, and uploading methods for transferring the generated pages to the web-server. To minimize the size of the database only the most current measurements for the most important sensor observations were included. Exceptions to this rule were the weather-station observations, includ- ing air temperature, wind speed, and irradiance which were kept for a week to enable calculations of extremes and sums. Fig. 3. Clickable map depicting the between a Danish and an English lan- Another important issue was the open- layout of the total greenhouse guage version of the web site. ing and closing routines for the Paradox operation of the agricultural univer- The next screen (Fig. 3) is a map database system. The closing operation sity. depicting the layout of the total green- was especially time consuming. To im- The main welcome screen (Fig. 2) house operation and is a more complex prove the performance, the access meth- was a simple web page consisting of an web page, using frames. The page con- ods were modified in such a way that the image from the greenhouses and data sisted of two sections: one included a database was only opened and closed from the weather station. The page menu with the names of all the con- once for every compartment per cycle. showed real-time climate data and cal- nected greenhouse compartments, the Initially this process required three min- culated values such as the minimum and other section was the actual map. The utes to generate the twenty web pages, maximum outside temperature from the user could select the area from which to primarily because of the parsing algo- last 24-hour period. These data were view data, either through the text menu rithm. A new standard string search popular not only with the employees at or by pointing at the map. This gave routine from the Systools package the university but with private garden- access to data from the selected com- (Turbopower Software, 1996) dramati- ers who use the information in their partment, which was then shown in the cally improved the performance. Cur- plant-growing practices. The main web frame previously occupied by the map. rently the system generates more than page of The Royal Veterinary and Agri- The general compartment page (Fig. 4) 40 web pages, using approximately 30 s cultural University (
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this could be done from any Internet- connected computer anywhere in the world. This also leads to consideration of the idea of changing the user interface of the ECCs to using a browser-based technology for monitoring and control- ling plant growth and climate. This type of application is also an efficient tool for speedily distributing research information to growers and the public. To demonstrate this, a complex energy-saving and production-optimiz- ing control system called IntelliGrow (Royal Veterinary and Agricultural Uni- versity, 2000) also was integrated with CYBGR4. CYBGR4 was used for up- loading dynamically generated graphs depicting the energy consumption in different compartments and giving many new persons the ability to follow the results of the research as it progresses from day to day. Conclusions and future aspects Based on the experiences with the CYBGR4 system, it was concluded that it was possible to construct and imple- ment web-driven systems that were easy to operate and which could supply rel- evant information to a wide range of different users interested in dynamic climate and process data from green- houses. The application proved easy to maintain and stable in operation. Fur- thermore, it was concluded that this sort of control system interface provided Fig. 4. An example of a standard web page containing real-time data from a many new possibilities for adding func- greenhouse compartment. tionality to the greenhouse control sys- tem. It would, for instance, be simple tion between the two servers needed to sideration, much work was spent on be open all the time. As an alternative all modifying the CYBGR4 code to make Table 1. The climate data and set points included in the standard files were uploaded in one single step it more independent of the above-men- greenhouse compartment page using the FTP protocol, where it was tioned events. layout. possible to integrate error-trapping into It would have been a simple matter the CYBGR4 software. This enabled also to use the application for changing Data from environmental control com- the application to avoid transmitting the set points of the climate controls. puter files, when network problems made this For security reasons we chose not to do Air temperature impossible. this in order to prevent unauthorized Inside irradiance The system has been fully opera- users or hackers from interrupting or Relative air humidity tional for more than 2 years and the even destroying important research ac- CO2-concentration stability has been very good as we have tivities. Ventilation window 1 position only experienced about 10 d of down A mere encrypted password pro- Ventilation window 2 position time. The main problems concerning tection would not be sufficiently safe, Shading screen closure percent stability were system errors in other but an implementation of an electronic Soil temperature applications running on the greenhouse signature as used by for instance bank- Current heating demand server, and general network problems ing web sites could be integrated in the Current heating water temperature which sometimes afflict the university system but would require major Set point air temperature day Set point air temperature night network as a whole. On some occasions restruction of the software. With this Set point ventilation it was also necessary to rebuild the data- level of security it would be a very Set point shading screen bases, which are sensitive to system convenient way of programming the Set point soil temperature day crashes. In order to take this into con- greenhouse control system, especially as Set point soil temperature night
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T&P 642 9/5/01, 12:01 PM to add E-mails or Short-Message-Sys- Ehler, N., 1991. Interfacing crop models to tem alarms which could be routed to the standard software for greenhouse climate responsible person, regardless of his control. Ecol. Modeling 56:245–257. physical location. The importance of Ehler, N. and J. Rystedt. 1990. From regu- this could be increased significantly in lation automat to information management the near future, with the proliferation of system: An analysis of the use and potential wireless handheld communicators and of the climate computer in greenhouse pro- cellular telephones using wireless access duction. Proc. 3rd Intl. Conf. Computers in to the Internet (WAP telephones). Agr. Ext. Prog. 1:82–94: The software technology here is Ehler, N. and J.M. Aaslyng. 2001. rather simple to implement and the Intelligrow: Integration with a generic green- source code is available for academic house environmental control computer us- purposes by contact to the authors. ing the BipsArch concept. Environmental Before using this software, it would be Modelling Software (In press). necessary to establish routines for real- Hashimoto, Y., T. Morimoto, and S. Funada. time communication with the ECC, for 1980. Computer processing of speaking instance by using the BipsArch system plant for climate control and computer aided and writing a device driver for the cur- plantation. Acta Horticulturae 115: 317– rent type of ECC. 325. Royal Veterinary and Agricultural Univer- Literature cited sity. 2000. IntelliGrow. Royal Vet. Agr. Univ., Dept. Agr. Sci., Hort. Sec., Borland International. 1992. Paradox user’s Copenhagen, Denmark. 11 Oct. 2000. guide. Borland Intl., Inc., Scotts Valley,
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