Thomas Scott Leach

US Patent:

45559309, Dec 3, 1985

Filed:

Feb 14, 1984

Appl. No.:

6/580028

Inventors:

Thomas W. Leach - Waldwick NJ
James Schaeffer - North Caldwell NJ

Assignee:

Control Instruments Corp. - Fairfield NJ

International Classification:

G01N 3100

US Classification:

73 23

Abstract:

A digital gas sensing system comprises a plurality of satellite subassembly units each including a central processing unit (CPU) and a plurality of "intelligent" sensors connected to the satellite subassembly units by a single pair of leads. The satellite subassembly units communicate to the sensors in a code having a predetermined number of digital bits. Each sensor has internal "intelligence" and recognizes its own unique address and responds to the satellite subassembly unit in a predetermined code that varies from the satellite subassembly unit code by one parity bit. This arrangement makes it possible for other sensors to distinguish between transmissions from the satellite subassembly unit and transmissions from other sensors. The net result is that the system is able to operate very reliably using only two leads to connect all of the sensors to the satellite sub subassembly unit thereby greatly reducing the wiring and installation costs of the system. To further expand the potential of the system it is also possible to link a plurality of satellite subassembly units together to a single master control unit.