Communications: electrical – Condition responsive indicating system – With particular system function
Reexamination Certificate
1999-04-09
2001-07-24
Pope, Daryl (Department: 2632)
Communications: electrical
Condition responsive indicating system
With particular system function
C340S508000, C340S533000, C340S870030
Reexamination Certificate
active
06265971
ABSTRACT:
BACKGROUND OF THE INVENTION
Typical building fire alarm systems include a number of fire detectors and notification appliances (e.g., audible and visual alarms) positioned throughout a building. The detectors and appliances, also referred to as peripherals, are connected to and intelligently controlled by a central panel. Signals from the detectors are monitored by the central panel which activates the notification appliances upon sensing an alarm condition.
It is desirable to have a single central panel monitor and control intelligent peripherals in more than one building due to considerations such as central panel cost. Long communication links such as fiber optics must then join remote peripherals to the main system loop.
SUMMARY OF THE INVENTION
The present invention provides a mechanism to inexpensively monitor the integrity of communication links connecting intelligent peripherals to a central panel. In particular, it may monitor the communication link between the two buildings to ensure there are no breaks or faults in the link between the buildings.
In accordance with the present invention, a monitoring system in an alarm apparatus includes a central panel for controlling operation of the alarm apparatus, first and second terminals, and a communication link interconnecting the first and second terminals. The first terminal may, for example, connect to the main loop to the panel, while the second terminal connects to remote peripherals. In a preferred embodiment of the present invention, the communication link comprises fiber-optic cables. The second terminal includes a communication device, such as a microcontroller, to communicate with the central panel. The first terminal includes a signaling device to signal to the communication device when there is a break in the communication link. Responsive to the signal, the communication device signals to the central panel that there is a break in the communication link.
A plurality of remote peripherals connected to and controlled by the central panel can include, for example, detectors to alert the central panel of an alarm condition (e.g., smoke or fire) and/or notification appliances which can include audible and/or visual alarms. The peripherals are controlled by messages received from the central panel. In a preferred embodiment of the present invention, the messages comprise a three-state signaling scheme which can include synchronization and data pulses.
The plurality of remote peripherals are connected to the second terminal. The first terminal is provided with a converter that converts the three-state signaling scheme to a two-state signaling scheme such that the communications can pass through the fiber-optic communication link. In order to distinguish the synchronization pulse from the data pulse in the converted two-state message, a frequency burst is embedded within the two-state synchronization pulse. Alternatively, the frequency burst can be embedded within the two-state data pulses.
In accordance with a further aspect of the present invention, the first terminal includes a circuit to change the frequency of the frequency burst in the event there is no communication received from the second terminal. The second terminal includes a discriminator that detects the frequency change and sends the signal to the central panel to indicate that there is a break in the communication link. In a preferred embodiment of the present invention, a frequency of 100 kilohertz in the frequency burst indicates normal operation, while a frequency of 400 kilohertz indicates a break in the communication line.
Thus, the alarm system of the present invention has the capacity to efficiently monitor the integrity of a fiber-optic communication link interconnecting a proximal location and a remote location. Furthermore, the alarm system includes the advantage of converting a three-state messaging scheme between a central panel and at least one intelligent peripheral to a two-state messaging scheme such that a fiber-optic link can be used as a communication link.
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Capowski Anthony J.
Dorr Timothy E.
Maier, Jr. Paul H.
Hamilton Brook Smith & Reynolds P.C.
Pope Daryl
Simplex Time Recorder Company
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