System having a plurality of service facilities with access control devices
A system has a plurality of groups (A, B) of service facilities (1 to 4) at each of which an access control device (5 to 8) with a read/write device (13 to 16) for a contactless data carrier (20) is provided. The read/write devices (13 to 16) of each group (A, B) are networked with a database (17, 18). To reduce the read time for reading the data carrier (20), the application data (23) are stored on the data carrier (20). The data carrier (20) has an identification number (21) as well as a transaction counter (22) with a transaction number which is changed upon a change of the application data (23). The application data (23), the identification number (21) and the transaction number are stored in the database (17, 18) of the group (A, B) to which the user goes. Upon access to a service facility (1 to 4) of said group (A, B) only the identification number (21) and the transaction number are read out from the data carrier (20) by the read/write device (13 to 16) as long as the application data are unchanged. In case of a match of the read-out identification number (21) and transaction number with the identification number and transaction number stored in the database (17, 18), the application data are retrieved from the database (17, 18), and in case of a valid access authorization check the access control device (5 to 8) releases access.