초록 ▼

The access control system according to the present invention provides for the centralized control of the system operating parameters, including all times, access codes, alarms, error messages, and pass-coded indications. The access control system communicates with a plurality of remote card readers,

The access control system according to the present invention provides for the centralized control of the system operating parameters, including all times, access codes, alarms, error messages, and pass-coded indications. The access control system communicates with a plurality of remote card readers, at which point the user enters a code to gain entry into the protected areas. The access control system according to the present invention selectively stores limited information at each card reader location, wherein access control is still maintained, even if the central data system becomes inoperative. Moreover, the communication between the central data system and the plurality of card readers includes data transfers through a plurality of subsystems, each having a data processing program therein. The system according to the present invention provides for efficient communication between asynchronous operating subsystems through the controlled use of a first-in-first-out (FIFO) data register pair. In this manner, each subsystem according to the present invention operates independently until a data transfer is initiated, causing the other operations to be suspended to permit the transfer of data. The FIFO allows for data to be transferred at different rates between subsystems, allowing freedom in subsystem operation and data transfer rates.

대표청구항 ▼

An access control system, comprising: a plurality of remote stations; a central station; and a data bus connected to said plurality of remote stations, wherein said central station includes: means for polling said remote stations, connected to said data bus to transmit to and receive data from a sel

An access control system, comprising: a plurality of remote stations; a central station; and a data bus connected to said plurality of remote stations, wherein said central station includes: means for polling said remote stations, connected to said data bus to transmit to and receive data from a selected plurality of remote stations, wherein said means for polling is responsive to an interrupt signal to commence transfer of data on said data bus and is responsive to a count signal providing an indication of the quantity of data to be transferred; means for controlling said plurality of remote stations connected to said means for polling, and a plurality of FIFO data registers connected to said means for polling and said remote stations to provide access control at said plurality of remote stations by said means for controlling, wherein one of said plurality of FIFO data registers provides said interrupt signals to said means for polling to initiate receipt of data into said means for polling, and provides said count signal.