Title of Invention

METHOD AND SYSTEM FOR MULTI-CLIENT MULTI-INSTRUMENT WORLD WIDE WEB-BASED DATA ACQUISITION

Abstract

Web-based data acquisition, the process of acquisition of data from remotely located instruments through the World Wide Web, is achieved by connecting various sensors and equipments to end-servers that are all connected to a common dispatcher as shown in Figure 1. Multiple clients or users can acquire data and the access is controlled by a scheduler using semaphores. Multiple instruments can be accessed by the clients. The acquired data is output in textual and graphical form. The system serves as a web-based virtual laboratory for educational and research use.

Full Text

Field of the Invention The present invention relates generally to measurement technology and specifically to the acquisition of data remotely using the World Wide Web via clients connecting to a dispatcher which in turn contacts various servers attached to the instruments and sensors. Background of the Invention The following discussion of prior art provides background information. Data acquisition for various applications (without the use of the Internet) has been performed by several groups of researchers in the past. A related reference is: J.L. Malaquias, P. Almeida, P. Amilcar, N. Cruz, C.M.B.A. Correia, "An integrated sys¬tem for nuclear data acquisition", IEEE Transactions on Nuclear Science, Vol. 44, 1997, pp. 411-415. A computer-based virtual instrument for flicker measurement is also, reported in the lit¬erature. The related reference is S. Caldara, S. Nuccio and C. Spataro, "A virtual instrument for measurement of flicker", IEEE Transactions on Instrumentation and Measurement, Vol. 47, No. 5, Oct. 1998, pp. 1155-1158. The distinguishing features of this invention as compared with prior art are (i) Re¬mote data acquisition utilizing the World Wide Web as the network medium, (ii) Instru¬ment/sensor being available as a Uniform Resource Locator (URL) across the World Wide Web, (iii) Provision to validate input data at the client side, (iv) Provision to gather and store data available for only a short period of time (such as in earthquakes), (v) Process to enable multiple clients to acquire data from a single instrument located remotely (across the Internet) based on appropriate queuing and (vi) Process for acquisition of data re¬motely by one or more clients from multiple instruments (with different interfaces such as dedicated or card-based) connected to a computer and displayed in text and graphical formats on the client browser. Object of the Invention The primary object of the present invention is development of a system for web-based data acquisition. It is also the object of the present invention to devise a mechanism for acquisition of data from a single instrument by multiple clients. It is further the object of this invention to develop a process for data acquisition from multiple instruments (with different interfaces) by one or more clients. It is also the object of this invention to perform acquisition from instruments that provide data for only a short period of time. Finally, it is the object of the present invention to present data acquired in text and graphical formats. Summary of the Invention The present invention is a method and system for multi-client acquisition of data from one or more remote instruments using the internet and in particular via GUI-based browsers for the World Wide Web. According to this invention, the process of acquiring data from various physical instru¬ments is triggered by remote clients operating from terminals in a virtual laboratory as shown in Figure 1. The terminals may simply represent multiple browser windows on the same computer. A second aspect of the invention is identification of the active instruments/sensors for informing the clients. A third aspect of the invention is a dispatcher configured to provide support for threads to transfer client service request to the appropriate instruments. The transfer is facilitated by a look-up table provided on the dispatcher. The dispatcher performs the additional role of providing security to the system by isolating the end-servers and instruments from the clients. In particular, the system supports two modes of access of the devices: one via a URL requiring a login and a password (to access specific devices) and a second URL that enables access of other devices without a login/password. A fourth aspect of the invention is that multi-client access to a given instrument/sensor at a given time is controlled by the dispatcher using a mechanism based on semaphores. Semaphores allow just one process at a time to access critical regions of code and data. In particular, the dispatcher which also functions as the scheduler sends the requests to the individual end-servers. Any end-server, however, cannot send multiple requests to a device connected to it at the same time. Only after processing one request can an end-server process a second request. This is accomplished by use of semaphore concept that allows access to only one process to the portion of code {critical region) that corresponds to sending request to the instrument/sensor for data. Another aspect of the invention is that the system supports two modes for handling the data acquired: (i) Direct transmission of acquired data to the client without any in- termediate storage in text as well as graphical format as shown in Figures i and 3 and (ii) Caching of the acquired data at the server side to facilitate applications that provide data for only a short period of time. The system provides mechanisms for high speed operation by validation of client input at the client side itself. Further, threads corresponding to requests for data from different instruments run simultaneously. Description of the Accompanying Drawings Figure 1 gives the architecture of the web-based data acquisition system. Terminals rep¬resent a computer or simply a client browser through which users can acquire data from various instruments/sensors. The dispatcher server receives client requests and sends them to the appropriate end-servers. The client to dispatcher communication is using HTTP. COM in the architecture denotes a serial communication port for instruments that support an RS232-C interface. Example of an instrument for attachment is a dig¬ital multimeter whose output is shown in Figure 2. The Data Acquisition (DAQ) card represents a plug-in data acquisition card that can be used with a variety of sensors. An example is the thermocouple unit whose output is shown in Figure 3. PCLD-789D is the specific data acquisition card used in the setup described. The third possibility is a General Purpose Interface Bus (GPIB) interface used with equipments such as signal generators and oscilloscopes. LANC in the architecture denotes a LAN connector while Sensor Setup is a combination of different sensors connected as a single unit. The left side of the diagram shows output at various stages after contacting the server. The VIRTUAL LAB list on Terminal 1 is obtained after the system identifies the active devices. Terminals 2 and 3 indicate client input for access of the multimeter and the thermocouple units respectively. Sample output from the digital multimeter that supports the RS232-C interface after execution of the data acquisition application is given in Figure 2. Sample output on the client computer from the thermocouple unit (consisting of 16 channels) interfaced using a dedicated DAQ card is shown in Figure 3. Description in Respect of Working of the Invention Clients can gather data from the instruments by connecting to the dispatcher through HTTP at the application layer. A list of active instruments is first provided to the clients from which a choice is made. The appropriate instrument characteristics are then made known to the client. The client fills out the forms choosing appropriate measurement parameters for data acquisition from a specific instrument. The dispatcher receives the request, queues suitably and transmits the request to the appropriate end-server. The end-server performs the acquisition from the instrument, transmits the data to the dispatcher which then passes it on to the remote client (browser) that presents the results in graphical and textual formats. Advantages of the Invention Remote data acquisition is valuable in a variety of contexts. Collaborative experimen¬tation and analysis of data pertaining to earthquakes or other phenomenon occurring remotely requires a facility and system to permit clients to gather and examine data independently. The setup requires no commercial software tool to accomplish data acquisition. In particular, freeware to process programs written in HTML, JavaScript, VML and Perl are adequate. Modification of the arrangement for handling new instruments with similar interfaces is facilitated in this freeware-based approach. It is therefore appropriate for academic and research use. We claim:- 1. A system for web-based data acquisition from one or more instruments, the system comprising of: (i) Terminals, operated by clients, that constitute a part of the virtual remote laboratory (ii) the Internet connection (iii) Dispatcher (iv) End-servers (server 1, ..., server n) and (v) Measuring instruments and sensors connected to the end-servers by various means such as using the COM port (via the RS232-C interface), Data Acquisition (DAQ) card or General Purpose Interface Bus (GPIB). 2. A method for web-based data acquisition wherein the process of acquiring data from various physical instruments is triggered by remote clients operating from terminals in the virtual laboratory. 3. A method, as claimed in Claim 2, in which the list of active instruments/sensors is identified for clients. 4. A method, as claimed in Claim 2, wherein the dispatcher is configured to provide support for multi-client and multi-instrument access using threads to send request to and receive response from the appropriate instruments. 5. A method, as claimed in Claim 2, wherein clients are authenticated using the dispatcher that also keeps track of the system usage. 6. A method, as claimed in Claim 2, wherein multi-client access to a given instrument at a given time is controlled by the dispatcher using semaphores. 7. A method, as claimed in Claim 2, that supports two modes of operation: (i) Direct transmission of acquired data to the client without any intermediate storage in text as well as graphical format and (ii) Caching of the acquired data at the server side to facilitate applications that provide data for only a short period of time.

Documents:

794-mas-2001 abstract duplicate.pdf

794-mas-2001 abstract.pdf

794-mas-2001 claims duplicate.pdf

794-mas-2001 claims.pdf

794-mas-2001 correspondence others.pdf

794-mas-2001 correspondence po.pdf

794-mas-2001 description (complete) duplicate.pdf

794-mas-2001 description (complete).pdf

794-mas-2001 drawings duplicate.pdf

794-mas-2001 drawings.pdf

794-mas-2001 form-1.pdf