CA2183106A1

CA2183106A1 - Network pc supervised alarm system

Info

Publication number: CA2183106A1
Application number: CA002183106A
Authority: CA
Inventors: Michael A. Muret; Bob R. Jackson
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-08-12
Filing date: 1996-08-12
Publication date: 1998-02-13

Abstract

A method and system for monitoring equipment in a network environment are provided. Such equipment could be, but may not necessarily be, computers, printers, monitors, and other computer hardware. The system incorporates existing network cabling in the building which must contain a plurality of conductors, of which, at least two conductors must not be utilised by the existing network protocol. The system uses the two unused conductors to create a current loop which can be monitored from a central location. A
specific resistance is fastened to the monitored equipment, and a voltage comparator at the central location activates an alarm if the resistance changes. The system is designed so that it can be installed onto existing network structures using common network patch cables, and without permanently defacing the monitored equipment.

Description

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Description:
The system utilises current network cabling technology which carries computer network signals to and from COJIIInllel equipment and a network concentrator. The system injects an alarm signal into the existing cabling system, near the Conce~ dlUI, on conductors that are normally unused by the computer network.
The alarm signal is terminated at the cv~ ulel equipment so that an alarm is triggered when the collll,ute equipment is disconnected from the cabling system.
The system is designed to work whether the connected computer equipment is powered on or off, since there is no electrical connection between the alarm signal and the computer or network.
The system is comprised of three distinct parts: The monitoring panel, the cabling system, and the equipment interface.

Monitoring Panel:
The monitoring panel is connected to the existing network system using standard RJ-45 jacks. For each piece of equipment that is to be protected, there is an input jack and an output jack on the panel as shown in Figure 1. The input jack is for the network signal coming and going to the network concentrator, and the output jack is for both the network and monitoring signals coming and going to the monitored equipment.
Network concentrators have a single RJ-45 jack for each network device. Without the monitoring system in place, the jacks on the concentrator are supposed to be patched to the cabling system with short lengths (between 0.5m and 3.0m) of twisted-pair cable having RJ-45 plugs on both ends.
The monitoring panel is inserted into the system by plugging the short patch cable to the panel input jack. A second patch cabled connects the panel output jack to the cabling system.
Any network equipment that does not require monitoring does not need to be patched through the monitoring panel. Conversely, any non-network equipment the requires monitoring does not need to be patched to the concentrator.
The monitoring panel may also be integrated into the concentrator so that the usual single patch cable from the conc~ -d~ /,..onitoring panel to the cabling system is the only connection required for both the network and the monitoring system. Figure 2 shows this configuration.

,~ 3 /C~ (g 2 The first six conductors of the input RJ-45 jack are connected directly to the first six conductors of the output jack to pass the network signal through. Only the seventh and eighth conductors of the output jack are used by the alarm circuit (Pin 7 and Pin 8 in Figure 3). When the alarm is armed, the impedance (Z in Figure 3) across those conductors is equal to the constant resistance inserted at the equipment end plus somc ~p:~it~rlce and an insignificant amount of resistance added by the cabling.
A voltage comparator makes sure that the impedance does not change. If the impedance does change, the output from one of the two op-amps in the CUI~I~JdldLUI will rise to the supply voltage of the op-amp and trigger an SCR (SCR in Figure 3). The capacitor (C in Figure 3) is used to offset the cabling capacitance when the circuit is first powered up or reset.
Diodes are used at the outputs of the op-amps and SCR so that multiple comparators can be used to trigger a single SCR.

Cabling System:
The monitoring system was designed specifically for a cabling system that offers at least two conductors more than network system requires. It will also function equally well if the user installs a completely separate cable specifically for the monitoring system alone.

Equipment Interface:
The equipment interface unit is comprised of a small plastic box that has a I .5m cable and RJ-45 plug for the incoming signal from the monitoring panel, and a short cable with an RJ-45 plug for the network connection to the computer (Figure 4). The plastic box is attached to the protected equipment using two-sided sticky tape. Like the monitoring panel, the first six conductors of the input plug are connected directly to the output plug. The seventh and eighth conductors of the input plug are connected to the terminating resistor and a tamper switch.
The tamper switch opens the circuit and triggers the alarm the circuit if the interface unit is removed from the equipment.

Claims

Claims:

1. A computer equipment alarm system which comprises: a dual operational amplifier circuit that monitors an unbalanced resistor circuit in such a way that the operational amplifiers are both normally latched to their negative supply voltage until one of the resistances significantly changes; a constant voltage across the said resistor circuit; one resistor which is part of the resistor circuit, but is permanently attached to the said computer equipment; two conductors in a network cable which are not used by the network and connect the single resistor on the said computer equipment to the rest of the said resistor circuit.