Patent ID: 6091328
Filing Date: 2000-07-18
Classification: G08B

Abstract:
A fire alarm system in which a fire alarm signal receiving device polls a plurality of terminal devices such as fire sensors, transmitters, manual boxes, and/or other controlled devices, thereby acquiring terminal device information from said terminal devices, making decisions, displaying information, and/or controlling said terminal devices,wherein said fire alarm signal receiving device comprises:first active bit counting means for counting the number of active bits contained in an address code and a command code to be transmitted to said terminal devices, said number of active bits being counted separately for each code;first number-of-active-bits adding means for determining the sum of the numbers of active bits by adding together the respective numbers of active bits counted by said first active bit counting means;first inverting means for determining an inverted value by inverting the sum of the numbers of active bits given by said first number-of-active-bits adding means;primary sum code generating means for generating a primary sum code by removing the most significant bit of said inverted value given by said first inverting means; andfirst transmission means for transmitting said address code, said command code, and said primary sum code;each of said terminal devices comprises:second active bit counting means for counting the number of active bits contained in said address code and said command code received from said fire alarm signal receiving device, said number of active bits being counted separately for each code;second number-of-active-bits adding means for determining the sum of the numbers of active bits by adding together the respective numbers of active bits counted by said second active bit counting means;second inverting means for determining an inverted value by inverting the sum of the numbers of active bits given by said second number-of-active-bits adding means;first sum code generating means for generating a first sum code by removing the most significant bit of said inverted value given by said second inverting means;first judgment means for judging whether said first sum code is equal to said primary sum code received from said fire alarming signal receiving device;third active bit counting means for counting the number of active bits contained in a return-back data to be returned to said fire alarm signal receiving device, said address code received from said fire alarm signal receiving device, and said command code received from said fire alarm signal receiving device, said number of active bits being counted separately for said data or each code, said number of active bits being counted when said first sum code is equal to said primary sum code;third number-of-active-bits adding means for determining the sum of the numbers of active bits by adding together the respective numbers of active bits counted by said third active bit counting means;third inverting means for determining an inverted value by inverting the sum of the numbers of active bits given by said third number-of-active-bits adding means;secondary sum code generating means for generating a secondary sum code by removing the most significant bit of said inverted value given by said third inverting means; andsecond transmission means for transmitting said return-back data and said secondary sum code to said fire alarm signal receiving device; andsaid fire alarm signal receiving device further comprises:fourth active bit counting means for counting the number of active bits contained in the return-back data received from any of said terminal devices, said address code to be transmitted to said terminal device, and said command code to be transmitted to said terminal device, said number of active bits being counted separately for said data or each code;fourth number-of-active-bits adding means for determining the sum of the numbers of active bits by adding together the respective numbers of active bits counted by said fourth active bit counting means;fourth inverting means for determining an inverted value by inverting the sum of the numbers of active bits given by said fourth number-of-active-bits adding means;second sum code generating means for generating a second sum code by removing the most significant bit of said inverted value given by said fourth inverting means; andsecond judgment means for judging whether said second sum code is equal to said secondary sum code received from said terminal device.