System and method of extending communications with the weigand protocol

Abstract

An extension of the industry standard Wiegand protocol for enabling two way extended communication, enhanced error detection, encryption, multiple reader capability, and enhanced information regarding the embedded data stream between a Wiegand device such as a card reader and a control panel on the existing 5-wire bus structure without requiring the modification to the existing infrastructure.

1 . An access control security system comprising: 
 a) a control panel;    b) a plurality of access control groups, each access control group interconnected to the control panel on an independent multi-wire data bus, each access control group comprising: 
 an access interface unit comprising: 
 data output means for transmitting data onto the data bus to the control panel,  
 data input means for receiving data via the data bus from the control panel,  
 processing means, interoperating with the data output means and the data input means, for operating data transfers over the data bus, the processing means adapted to generate a data message for transmission onto the data bus via the data output means, the data message comprising a Wiegand message field in accordance with the Wiegand protocol and an extended data field.  
 
   
   
   
       2 . The system of  claim 1  wherein the extended data field comprises a status information field indicative of a status condition of the access interface unit.  
   
   
       3 . The system of  claim 1  wherein the access interface unit further comprises user ID reading means for reading an ID device.  
   
   
       4 . The system of  claim 3  wherein the ID reading means is configured to read an access control card.  
   
   
       5 . The system of  claim 3  wherein the ID reading means is configured to read a data transponder.  
   
   
       6 . The system of  claim 3  wherein the ID reading means is configured to read a data-carrying key fob.  
   
   
       7 . The system of  claim 3  wherein the ID reading means is configured to read biometric data from a user.  
   
   
       8 . The system of  claim 3  wherein the processing means interoperates with the ID reading means, and wherein the extended data field further comprises an information field indicative of a property of an ID read by the ID reading means.  
   
   
       9 . The system of  claim 1  wherein at least one access control group comprises a plurality of access interface units, and wherein the extended data field comprises address information uniquely identifying each access interface unit in an access control group.  
   
   
       10 . The system of  claim 1  wherein the processing means is further adapted to utilize an error detection algorithm as a function of data contained within the extended data field.  
   
   
       11 . The system of  claim 10  wherein the error detection algorithm is a cyclic redundancy check (CRC), and wherein the extended data field is appended with the CRC.  
   
   
       12 . The system of  claim 2  wherein the access interface unit further comprises user input means for accepting user input functions, and wherein the status condition of the access interface unit indicates a function input by a user via the user input means.  
   
   
       13 . The system of  claim 12  wherein the input means comprises at least one pushbutton.  
   
   
       14 . The system of  claim 13  wherein the function of the pushbutton is a door bell function.  
   
   
       15 . The system of  claim 2  wherein the access interface unit comprises external status input means for accepting external status data from an external device coupled thereto, and wherein the status information field of the extended data field comprises the external status data.  
   
   
       16 . The system of  claim 15  wherein the external device is adapted to measure temperature, and wherein the external status data comprises the measured temperature.  
   
   
       17 . The system of  claim 15  wherein the external device is adapted to detect a change in light incident thereon, and wherein the external status data comprises data indicative of a change in light.  
   
   
       18 . The system of  claim 15  wherein the external device is adapted to detect physical tampering with the access interface unit, and wherein the external status data comprises an tamper indication.  
   
   
       19 . The system of  claim 2  wherein the processing means is further adapted to generate supervision data on a periodic basis, and wherein the status information field comprises the supervision data.  
   
   
       20 . The system of  claim 2  wherein the processing means is further adapted to detect a malfunction of the access interface unit, and wherein the status information field comprises data indicative of a malfunction.  
   
   
       21 . The system of  claim 1  wherein data transfers are made to the control panel using the electrical and information content of the Wiegand protocol via the Data “0” and Data “1” output signals.  
   
   
       22 . The system of  claim 1  wherein data transfers are made by the control panel using the electrical characteristics of the Wiegand protocol via the LEDCTL input signal as a serial protocol.