Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1987-09-15
1989-07-11
Crosland, Donnie L.
Communications: electrical
Condition responsive indicating system
With particular system function
340506, 340505, 340531, G08B 2600
Patent
active
048475939
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a transmission circuit of a fire protection/security system, and more particularly to a transmission circuit which is disposed in a control panel or in each terminal device of a fire protection/security system wherein the control panel individually polls a plurality of terminal devices to read-in terminal information from the terminal devices, to judge and/or display the information, or to control the terminal devices.
2. Background Art
There is known in the art a fire protection/security system, such as a fire alarm system or an antitheft system, wherein the control panel of the system polls terminal devices and reads in monitoring information from the terminal devices so as to judge the occurrence of an abnormality such as a fire or an intrusion and/or to send control information to the terminal devices.
In the prior-art fire protection/security system, a signal different from the one that ought to be sent is, in some cases, sent from the control panel on account of troubles in, e. g., the signal sending means within the control panel. Similarly, a signal different from the one that ought to be sent is, in some cases, sent from any of the terminal devices on account of troubles in, e. g., the signal sending means within the terminal device.
In addition, when two or more of the terminal devices send signals simultaneously, the signals are combined, and a signal different from the one that ought to be sent is transmitted. The same applies in the case where the terminal device and the control panel send signals simultaneously, resulting in the transmission of a signal different from the one to be sent. Further, in a case where noise has entered the transmission line which connects the control panel with the terminal devices or where the transmission line has short-circuited, a signal different from the one to be sent is, in effect, sent.
In the aforementioned cases, there is the problem that a terminal device other than the one called during polling responds erroneously or that the control panel fails to correctly identify a zone where an abnormality has occurred.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the problem of the prior-art system stated above, and has for its object to provide, in a transmission circuit which is disposed in a control panel or in each terminal device of a fire protection/security system wherein the control panel individually polls a plurality of terminal devices to read in terminal information from the terminal devices, to judge and/or display the information, or to control the terminal devices, a transmission circuit of a fire protection/security system by which one can know for certain that a right signal to be sent by the control panel or the terminal device has been actually sent.
In order to accomplish this object, the present invention consists of a transmission circuit which is disposed in a control panel or in each terminal device of a fire protection/security system wherein a plurality of terminal devices are individually polled by the control panel to read in and/or judge terminal information from the terminal devices, to display judged results etc. or to control the terminal devices on the basis of the judged results, and is characterized by comprising a signal sending means for sending a signal to a signal line, memory means for storing a signal to be sent to the signal line, and a coincidence decision circuit for deciding a coincidence between the signal sent from said signal sending means and the signal stored in said memory means.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an embodiment of the present invention; while
FIG. 2 is a flow chart showing the operation of the embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing an embodiment of the present invention.
A control panel RE is the control panel of a fire protection/security system such as a fire alarm system or an antitheft system. It includes a tr
REFERENCES:
patent: 3508260 (1970-04-01), Stein
patent: 3713142 (1973-01-01), Getchell
patent: 4206449 (1980-06-01), Galvin et al.
patent: 4658243 (1987-04-01), Kimura et al.
52-25993, 2-26-77, Japan, Kazumasa Murakami.
51-122398, 10-26-76, Japan, Shigeo Ohara et al.
54-95875, 7-28-79, Japan, Hisakatsu Honda.
Crosland Donnie L.
Nohmi Bosai Kagyo Kabushiki Kaisha
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