Abstract:

A prepayment safe system based on centralized control is designed and implemented. The system consists of industrial personal computer, coin acceptor, bill acceptor, slave computer, power, etc. The structure diagram is given, the industrial personal computer instead of the system of microchip and LCD is the host, a communication protocol relevant to slave computer is realized, and communication protocol relevant to bill acceptor, as well as the key points of programming in software development is analyzed. The host software is programmed and rapidly developed by using C++ Builder 6. The system uses InterBase 6.5 as its database and it has lower cost compared with largescale databases such as SQL Server and Oracle. The modules of user interface, communication, system set, information record, advertisement are introduced in detail. To assure the accuracy for the  changemaking, an algorithm of changemaking problem based on this system is put forward. Through actual application, the stability and reliability of the system are proved, and the user demands are also met.

Key words: prepayment safe;RS485;communication protocol;software design;changemaking problem