The present invention generally relates to collecting information from vending machines in the vending industry, and in particular relates to efficiently collecting such information on an ongoing basis. 
In an attempt to more efficiently service and stock vending machines, vending machines have been equipped with communication electronics to provide information to a central location for processing.  Communicating vending information to and from vending machines is generally referred to as xe2x80x9conline vending.xe2x80x9d For online vending, the information collected from a vending machine is transmitted across large distances to a central server computer by telephone line, radio signal, or the like, where it is used for management purposes.  The costs associated with such data transmission have a major impact on the profitability of the vending operation, since the data is normally sent on a daily basis.  If the amount of data to be transmitted can be significantly reduced, the cost of data transmission is correspondingly reduced, and the viability of the vending operation is enhanced.  Electronically controlled vending machines provide a large quantity of sales and fault related data, and the challenge has been to reduce the data transmitted without compromising the quality or quantity of data available at the central server computer. 
Previous attempts have included selective sending of the data.  For example, information is sent to the central server computer only on selected days of the week, or only certain types of information are sent.  The disadvantages of these methods are that while data volume and hence costs are reduced, the available data at the central server computer is also reduced.  For example, if a vending data collection unit is set up to call only on week nights, the machine may run low on stock during a weekend, and the machine will not be serviced because it does not call in over the weekend.  There is also a reduced amount of data available for the technical maintenance of both the vending machines, and the data reporting system.  Furthermore, if the unit only reports sales information, then when a vending machine fault occurs, it will not be communicated, and the vending machine may be left in a condition where it is unable to sell for some period of time before a dissatisfied customer reports the machine malfunction. 
In a system that only reports certain types of vending machine data, there is often manual overhead involved with managing which types of data are to be returned and which are not as the vendor operators extend their ideas as to what data is now essential.  Many systems require periodic changes in memory, such as a read only memory (ROM).  These changes often require the memory to be physically replaced with one reprogrammed with a new set of software in order to make changes in the types of data reported, and this is a costly and time consuming operation in the light of the large number of vending machines that exist. 
As such, there is a need to provide a vending machine or related interface that overcomes the above disadvantages while significantly reducing the quantity of data transmitted. 
The present invention provides an efficient system for providing vending information from vending machines to a central processing system.  Difference indicia representing changes in vending information from a previous update is sent to the central processing system from a vending machine.  The difference indicia provides sufficient information for the central processing system to update the data kept at the central processing system to reflect new vending information.  Preferably, reference vending data is kept at the vending machine and at the central processing system.  New vending data is compared with the reference vending data to identify differences between the new vending data and the reference vending data.  These differences are used to generate the difference indicia sent to the central processing system.  Upon receipt by the central processing system, the difference indicia is used to modify the reference vending data stored at the central processing system to reflect the new vending data. 
Preferably, the reference vending data and the new vending data at the vending machine are compared on a line-by-line basis.  Each line will represent a record having a record type and associated data for the record type.  Based on the comparison between the new vending data and the reference vending data, insert, delete, and replace commands are generated to form the difference indicia.  An insert command will insert the corresponding line to reflect new vending data in the reference vending data at the central processing system.  A delete command will cause a corresponding line to be deleted from the reference vending data at the central processing system when the new vending data no longer has a corresponding line or record.  The replace command is preferably used when lines in the new and reference vending data have a similar record type, but different data associated therewith can also be used as a simultaneous delete and insert.  As such, the replace command may provide information to change the data associated with a given record in the reference vending data at the central processing system. 
The present invention may be implemented in a vending machine control system or in a vending machine user interface associated with a vending machine controller in a vending machine.  Either the vending machine controller or the vending machine user interface is preferably associated with communication electronics to communicate the difference indicia via direct or wireless communications to the central processing system, over any number of networks.  The concepts of the present invention may be implemented in the hardware of the vending machine, vending machine controller, or vending machine user interface as well as in software, process, or method.  The software of the present invention may be implemented in various types of computer readable media, including, but not limited to programmable memory devices, magnetic disk, optical disk, and the like. 
Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.