Emergency access method in centralized monitoring system

• US 4,737,783 A
• Filed: 05/20/1983
• Issued: 04/12/1988
• Est. Priority Date: 05/20/1982
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Okamoto, Takaaki, Machino, Katsuyuki, Tanaka, Hidehiko, Ise, Masahiro, Terasaka, Teiji, Matsubara, Toshiyuki
• Primary Examiner(s): Weldon, Ulysses
• Application Number:
  US06/496,395
• Time in Patent Office: 1,789 Days
• Field of Search: 340/825.05, 340/825.12, 340/825.5, 340/825.51, 340/825.08, 340/533, 370/86, 370/88, 370/94, 370/85, 370/96
• US Class Current: 340/3.51
• CPC Class Codes: G08B 25/06 using power transmission lines
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H04B 3/546 Combination of signalling, telemetering, protection circuits for remote indication of supply or distribution network condition H02J13/00
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04Q 9/14 Calling by using pulses

Abstract

The present disclosure is directed to an emergency access method in which in the event that an emergency data occurring at a particular terminal is fed immediately to a central system but collides with any emergency data from a different terminal such collision is sensed and a signal in that data is delayed in a random number manner through the use of an appropriate random number generating algorithm in order to avoid such collision within a short length of time.

Claims

1. In a centralized monitoring system including a central system and a plurality of terminals and indoor power supply wiring connected as a data transmission path between said central system and said terminals, an emergency access means comprising:

data request means for enabling said central system to call for data from said terminals, said data request means including means for permitting said central system to transmit emergency inquiry codes to all of said terminals as well as regular inquiry codes that are polling signals having address information for each of said terminals;

data transmission means for transmitting data from said terminals to the central system in response to the data request means, said data including data from a terminal that is polled by a proper regular inquiry code as well as emergency data from a terminal in response to the transmission of an emergency inquiry code, which terminal has not yet received an acceptance signal from said central system indicating that a given emergency data from said terminal has previously been accepted by said central system; and

means for sensing collisions of emergency data sent immediately upon occurrence of an emergency condition from a particular one of said terminals to said central system with other emergency data from different terminals, the existence of a collision being determined by the absence of an acceptance signal, the collision sensing means permitting said data request means to continue to transmit an emergency inquiry code as well as said polling signals;

said terminals including means for delaying the transmission of said emergency data with random delay times and then re-transmitting said emergency data in response to the sensing of a collision by said collision sensing means.

2. The emergency access means of claim 1 wherein the delaying means includes a delay flag for generating random numbers for postponing re-transmission of the emergency data, upon receipt of said emergency inquiry code.

3. The emergency access means of claim 2 wherein said delay flag generates said random numbers through the use of an appropriate random number generating algorithm that is a function of the individual address of the respective terminals.

4. A method for controlling data flow in a centralized monitoring system having a plurality of terminals, each terminal having an individual address, and a shared monitor, comprising the steps of:

polling the plurality of terminals by means of a plurality of polling signals produced by the monitor, each of said plurality of polling signals corresponding to one individual address of the plurality of terminals, with each of the plurality of terminals being polled once during a polling cycle;

providing an emergency data access slot between each successive polling signal of a polling cycle, said emergency data access slot permitting at least one of the plurality of terminals which has not yet been polled during said polling cycle to transmit emergency data to the central monitor;

sensing a collision of emergency data transmitted by at least two of the plurality of terminals during one emergency data access slot;

delaying retransmission of each emergency data that has been involved in a collision of emergency data with random time delays produced at each of said plurality of terminals, the delay of the retransmission avoiding subsequent collisions of each of the emergency data involved in a first collision.

5. The method of claim 4, wherein the step of delaying retransmission includes generating random numbers for random time delays with a delay flag.

6. The method of claim 5, wherein said step of generating random numbers is carried out in accordance with a random number generating algorithm, said algorithm being a function of the individual addresses of the plurality of terminals.