GB2164180A - Remote monitoring apparatus - Google Patents

Remote monitoring apparatus Download PDF

Info

Publication number
GB2164180A
GB2164180A GB8422491A GB8422491A GB2164180A GB 2164180 A GB2164180 A GB 2164180A GB 8422491 A GB8422491 A GB 8422491A GB 8422491 A GB8422491 A GB 8422491A GB 2164180 A GB2164180 A GB 2164180A
Authority
GB
United Kingdom
Prior art keywords
monitoring apparatus
remote
remote monitoring
mother station
monitor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8422491A
Other versions
GB2164180B (en
GB8422491D0 (en
Inventor
Robert James Waddle
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JONES AUTOMATION Ltd J
Original Assignee
JONES AUTOMATION Ltd J
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by JONES AUTOMATION Ltd J filed Critical JONES AUTOMATION Ltd J
Priority to GB8422491A priority Critical patent/GB2164180B/en
Publication of GB8422491D0 publication Critical patent/GB8422491D0/en
Publication of GB2164180A publication Critical patent/GB2164180A/en
Application granted granted Critical
Publication of GB2164180B publication Critical patent/GB2164180B/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04QSELECTING
    • H04Q9/00Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
    • GPHYSICS
    • G08SIGNALLING
    • G08CTRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C19/00Electric signal transmission systems
    • G08C19/02Electric signal transmission systems in which the signal transmitted is magnitude of current or voltage
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04QSELECTING
    • H04Q2209/00Arrangements in telecontrol or telemetry systems
    • H04Q2209/80Arrangements in the sub-station, i.e. sensing device
    • H04Q2209/88Providing power supply at the sub-station

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

A remote monitoring system including a number of outstations in which one or more of the outstations can transmit monitored information back to a mother station without the use of local power source. <IMAGE>

Description

SPECIFICATION Remote monitoring apparatus The present invention relates to remote monitoring apparatus and more particularly to monitoring apparatus for use in hazardous environments.
The monitoring apparatus of the present invention finds particular application in the monitoring of carbon monoxide in mines but may be used to monitor other dangerous gases for example suplhur dioxide in for example sewage works, car parks, tunnels etc.
Known remote monitoring apparatus requires the provision of a power supply at the remote location. This power supply may be supplied by a battery. The provision of a battery necessitates continual checking, recharging and replacement which must be carried out carefully to avoid any loss of monitoring performance. In a system with a large number of monitoring points this is extremely costly.
It is an object of the present invention to obviate the above problem by providing a remote monitoring system which does not require a power source at the monitoring stations.
According to the present invention there is provided remote monitoring apparatus including a plurality of remote monitors for positioning at remote locations, means for connecting each monitor to a mother station to receive at the mother station a signal from said monitor indicative of the level of the monitored quantity, in which the remote monitor includes means to transmit its output signal to the mother station without using any local power source.
Preferably the output signal of each remote monitor is transmitted to the mother station as an analog quantity in particular by variation of the current level in a two wire circuit.
The mother station preferably includes a scanner which can sequentially scan each monitor and a data logger to record information transmitted from the remote locations.
The remote monitors are preferably grouped into groups of N monitors each connected to an N transducer outstation. In a preferred embodiment N is equal to 4. The advantage of this arrangement is that all N monitors can be addressed as a group thus increasing the scan speed of the system. By making N a relatively small number, for example 4 the flexibility of the system is not significantly reduced.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows in schematic form a monitoring apparatus according to the present invention; Figure 2 shows the mother station of Fig. 1 in greater detail; Figure 3 shows a typical sensor for use with the monitoring apparatus of Fig. 1; Figure 4 shows circuitry associated with a carbon monoxide sensor for conversion of the output to a form suitable for the present invention; and Figure 5 shows circuitry situated within an outstation for the reception of signals from sensors of various types and for conversion of the output signals from each type of sensor to a form suitable for the present invention.
With reference now to Fig. 1 the apparatus comprises a plurality of outstations 10. To each outstation in the designed system a maximum of four sensors 12, 14, 16, 18 may be connected. The sensors may be all of the same type or may be of different types.
Typical sensors suitable for connection as as follows: Carbon Monoxide (CO) sensor: JJA-ESCOM sensor Any 2 wire operated transmitting transducer providing a MA. output which is mantained under line resistance variations up to 1KQ and taking EMF from a remote source of 24v.d.c.
Max. Any self powered voltage output transducer desirably in the range 0-2v Max.
Any volts free potentmeter transducer desirably in range 0-2Kn.
Sensors are shown connected to only one outstation. In a practical system one or more sensors would be connected to each outstation up to maximum of 120 sensors connected to 30 outstations. The connectors 20 to each sensor are two core, the connection 22 between each outstation and the mother station 24 is twelve core.
The apparatus is shown in the context of a mine monitoring system the surface or nonhazardous area being separate from the underground or hazardous area as shown by the dotted line. Similar hazardous and non-hazardous areas will normally be present in most applications of the apparatus for example sewage works, car parks or tunnels.
For carbon monoxide monitoring it is extremely important to maintain a barrier between the non-hazardous and hazardous areas.
Thus within the hazardous area the cable 22 is for example at a maximum of 24 volts and no more than 50mAmp is allowed to flow cumulatively down all twelve cores. This is in order to avoid the possibility of any spark occuring should the cable be cut through by for example a roof fall in a mine.
For applications where it is not absolutely necessary to maintain an electricai safety barrier between a hazardous and non-hazardous region it is still advatagous to use low current levels in the cable 22 because this results in a low voltage drop in the cable thus allowing sensors to be connected up to 10 miles from the mother station.
With reference now to Fig. 2, the mother station 24 is shown in greater detail. A zener diode barrier 30 protects the hazardous area penetrated by the cable 22 from being subjected to voltage levels above an amount specified by the particular barrier. In a practical embodiment the voltage level is set at 24 volts. In mining systems the barrier is to British Standard IS 1833 and a suitable zener barrier is type MTL 165.
The cable 22 is therefore connected via barrier 30 to a scanner 32. Scanner 32 comprises switch means to address in turn each of the 30 outstations, one of which is shown in greater detail in Fig. 5.
Data is received from a scanned station by a data buffer 34. Each station may for example in a practical system be scanned once every 3 seconds giving a scan time of 100 milliseconds for each station and a scan rate of 40 sensors per second.
At each outstation an LED (see Fig. 5) is preferably turned on for the 100 millisecond period thus enabling a check to be made that the station is correctly connected to the mother station.
The mother station may also comprise means for displaying and/or recording the data. Such means comprises a data logger (Z80), 36, and data logger (Z80) main frame computer 38 with floppy disc back up 40 and an RS 232 data transmission interface capability I/O port 42. For the display of data a colour graphics monitor 44 may be used to provide graphical and hystogram information and a further V.D.U. 46 is used for the operator communication with the system using a keyboard 48. A dot matrix printer 50 provides a permanent record of data and a further data entry port 52 is provided for data to be entered, for display, from a different source, for example a non-hazardous environment.
With reference to Fig. 3 the sensors are connected to the outstations via a twin core cable via pins A and B. Preferably a waterproof screw thread connection indicated at 54 is provided to mate with a corresponding connection (not shown) on each cable 20. The sensor has access to the environment via grille 56.
The sensor, as stated above may be one of a number of types, a typical sensor being for sensing the concentration of carbon monoxide.
The electrical connection of such a sensor to the system is shown in Fig. 4. The output of sensor 60 is converted by the circuitry 62 shown in the dot-dash lined box into a variable D.C. current output at terminals A and B.
Thus as the level of carbon monoxide increases the current along the cable 20 increases by virtue of the change in conductance of the circuitry 62.
With reference now to Fig. 5, each sensor 12, 14, 16 or 18 is connected to a respective circuit RVC1, RVC2, RVC3 or RVC4 in each outstation 10. To accommodate various types of sensor manually operable switches SW1-SW4 are included within the respective circuits RVC1-RVC4. The switches are used to select SW1B and to energise SW1A the appropriate circuitry within RVC 1 to produce at highway data lines 5-5A a desired current output.
Selection of an outstation by an address present on lines 1, 1A; 2, 2A; 3, 3A; and 4, 4A.
Fig. 4. Shows the transducer circuit which is a high gain pre-amplifier with constant current transmission output stage. The micro amp output from the CO sensor is connected to inputs PL. 1 & PL.2 and forms the difference input to the pre-amplifier formed by operational amplifiers IC. 1 & IC.2.
The pre-amplifier is a high gain, ultra stable, low drift amplification stage with excellent common mode rejection.
The output from this pre-amplifier stage is connected to input 3 of IC.3 which acts as a comparitor comparing the signal at pin 3 with the reference source at pin 2 controlled by zener reference ZD.1, potentiometer VR.2 and resistor R.12. The output of IC.3 is used to control the current flow through transistor T.2 such that current in the loop is proportional to signal applied at input 3 of It.3. Zener diode ZD.2 clips the base voltage of T. 1 protecting transistor T.2 from overdriving.
The gain of this stage is controlled by VR.5 and once pre-calibrated the current flow through transistor T.2 is maintained independent of external loop resistance presented at terminals A & B forming a constant current loop. The automatic loop compensation is controlled by the connection from the emitter of T.2 to pin 2 of IC.3. Reduction in voltage at pin 2 of IC.3 resulting from increased loop load resistance causes an increase in the output from IC.3 which in turn increases the current flow through T.2 until the balance voltage point at emitter T.2 is re-established. Because the terminals A & B also source the current for the supply rails, current flow through the external loop represents a level proportional to the CO sensor plus an offset to supply the amplifier circuits. The offset required to power the operational amplifiers varies from unit to unit so the adjustable constant current circuit bleed formed by FET's T.3 & T.4 is used to pre-set this current offset to a fixed level ie.
2mA for a 2-10mA unit.
Fig. 5. Shows the outstation circuitry responsible for responding to highway addresses and thereby multiplexing the analogue values onto the data highway.
Terminas 1 thro 4A are connected to the address highway giving a maximum address reception capability of 8 lines 256 addresses.
In power free systems only 5 lines are used ie, terminals 1 thro 3. The address presented to the outstation terminals is compared with the outstation address as programmed on the DIL switches SW1 & SW2. If a correct comparison is attained by the comparitor circuit formed by IC's 1 thro 4 transistor TR2 is turned on via operational amplifier IC.5 and inductor coil L. 1 is energised and LED.1 is turned on. Four secondary L. 1 coils are connected to the data line switching FET's F. 1 thro F.4. These FET's in turn switch on to the data highway the analogue value which may be developed from any one of three transducer input types as selected by switches SW1A and SW1B.
The circuitry formed by IC.1, T.1,T.2, ZD.1 etc. on the RVC. 1 module is a constant current transmission stage developing a current output proportional to either a voltage or resistive input according to the transducers type connected. This circuit is identical to the similar stage described under Fig. 4.
Variable current outputs are controlled in the circuit data loops formed at terminals 5 & 5A, 6 & 6A, 7 & 7A, 8 & 8A. All the A designated terminals are held at the same operating potential and in some cases for cable core economy these may be commoned. (ie. Power Free 12 wire system terminals 5A, 6A, 7A & BR< 8A are connected in common to 3 cable cores).

Claims (8)

1. A remote monitoring apparatus including a plurality of remote monitors for positioning at remote locations, means for connecting each monitor to a mother station to receive, at the mother station, a signal from said monitor indicative of the level of the monitored quantity, in which the remote monitor includes means to transmit its output signal to the mother station without using any local power source.
2. A remote monitoring apparatus as claimed in Claim 1, in which the output signal of each remote monitor is transmitted to the mother station as an analog quantity.
3. A remote monitoring apparatus as claimed in Claim 2, in which the analog quantity comprises variation of the current level in a two wire circuit.
4. A remote monitoring apparatus as claimed in any one of Claims 1 to 3, in which the mother station includes a scanner which can sequentially scan each monitor and includes a data logger to record information transmitted from the remote location.
5. A remote monitoring apparatus as claimed in any preceding claim, in which the remote monitors are grouped into groups of N monitors each connected to an N transducer outstation.
6. A remote monitoring apparatus as claimed in Claim 5, in which N is equal to 4.
7. A remote monitoring apparatus as claimed in Claim 5 or Claims 6, in which each N transducer outstation is connected to the mother station by an M core cable, or one or more of said cores being used as address wires, one or more of said wires being used as signal wires and one or more of said wires being used as earth return wires.
8. A remote monitoring apparatus constructed substantially as herein described with reference to the accompanying drawings.
8 A remote monitoring apparatus as claimed in any one of Claims 5, 6 or 7, in which the N transducer outstation includes means for converting voltage input signals to an analog current quantity for transmission to the mother station.
9. A remote monitoring apparatus constructed substantially as herein described with refernece to the accompanying drawings.
CLAIMS Amendments to the claims have been filed, and have the following effect: New or textually amended claims have been files as follows:
1. A remote monitoring apparatus including a plurality of remote monitors for positioning at remote locations, means for connecting each monitor to a mother station to receive, at the mother station, a signal from said monitor indicative of the level of the monitored quantity, in which the remote monitor includes means to transmit its output signal to the mother station without using any local power source, in which the remote monitors are grouped into groups of up to N monitors each connected to an N transducer outstation, each N transducer outstation including multiplexing means powered from the mother station to address each monitor connected thereto in a sequential manner on being addressed by the mother station.
2. A remote monitoring apparatus as claimed in Claim 1, in which the output signal of each remote monitor is transmitted to the mother station as an analog quantity.
3. A remote monitoring apparatus as claimed in Claim 2, in which the analog quantity comprises variation of the current level in a two wire circuit.
4. A remote monitoring apparatus as claimed in any one of Claims 1 to 3, in which the mother station includes a scanner which can sequentially scan each monitor and includes a data logger to record information transmitted from the remote location.
5. A remote monitoring apparatus as claimed in Claim 1, in which N is equal to 4.
6. A remote monitoring apparatus as claimed in Claim 1 in which each N transducer outstation is connected to the mother station by an M cire cable, one or more of said cores being used as address wires, one or more of said wires being used as signal wires and one or more of said wires being used as earth return wires.
7. A remote monitoring apparatus as claimed in any one of Claims 5 or 6, in which the N transducer outstation includes means for converting voltage input signals to an analog current quantity for transmission to the mother station.
GB8422491A 1984-09-06 1984-09-06 Remote monitoring apparatus Expired GB2164180B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8422491A GB2164180B (en) 1984-09-06 1984-09-06 Remote monitoring apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8422491A GB2164180B (en) 1984-09-06 1984-09-06 Remote monitoring apparatus

Publications (3)

Publication Number Publication Date
GB8422491D0 GB8422491D0 (en) 1984-10-10
GB2164180A true GB2164180A (en) 1986-03-12
GB2164180B GB2164180B (en) 1988-03-30

Family

ID=10566330

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8422491A Expired GB2164180B (en) 1984-09-06 1984-09-06 Remote monitoring apparatus

Country Status (1)

Country Link
GB (1) GB2164180B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3631477A1 (en) * 1986-09-16 1988-03-24 Siegfried Schwarz NETWORK FOR DATA AND ENERGY TRANSFER
US10746586B2 (en) 2015-05-28 2020-08-18 Sonicu, Llc Tank-in-tank container fill level indicator
US10745263B2 (en) 2015-05-28 2020-08-18 Sonicu, Llc Container fill level indication system using a machine learning algorithm

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1344619A (en) * 1970-05-04 1974-01-23 Apv Co Ltd Control systems
GB1494240A (en) * 1974-07-10 1977-12-07 Bosch Gmbh Robert Vehicle electrical switching operation control apparatus
GB1538694A (en) * 1976-02-19 1979-01-24 Bendix Corp Data transmission and digital processing systems
GB1550701A (en) * 1975-05-12 1979-08-15 Western Geophysical Co Seismic data processing system and method
GB1554060A (en) * 1976-11-17 1979-10-17 Bendix Corp Data transmission system
GB2032665A (en) * 1978-10-02 1980-05-08 Wile & Co Inc M Point-of-manufacture data acquisition system
GB1598553A (en) * 1978-05-26 1981-09-23 Ferranti Ltd Data transmission systems
GB2093243A (en) * 1981-02-17 1982-08-25 Sparton Corp Addressable transducer
EP0082080A1 (en) * 1981-12-14 1983-06-22 Etablissement public dit: CHARBONNAGES DE FRANCE Method and apparatus for the transmission of signals, and use in the detection and/or measuring of the concentration of combustible gas in an atmosphere
GB2116764A (en) * 1982-03-11 1983-09-28 Distributed Control Syst Universal input-output device
EP0108903A2 (en) * 1982-11-12 1984-05-23 Dresser Industries,Inc. Universal interface method and apparatus for subsurface earth formation testing

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1344619A (en) * 1970-05-04 1974-01-23 Apv Co Ltd Control systems
GB1494240A (en) * 1974-07-10 1977-12-07 Bosch Gmbh Robert Vehicle electrical switching operation control apparatus
GB1550701A (en) * 1975-05-12 1979-08-15 Western Geophysical Co Seismic data processing system and method
GB1538694A (en) * 1976-02-19 1979-01-24 Bendix Corp Data transmission and digital processing systems
GB1554060A (en) * 1976-11-17 1979-10-17 Bendix Corp Data transmission system
GB1598553A (en) * 1978-05-26 1981-09-23 Ferranti Ltd Data transmission systems
GB2032665A (en) * 1978-10-02 1980-05-08 Wile & Co Inc M Point-of-manufacture data acquisition system
GB2093243A (en) * 1981-02-17 1982-08-25 Sparton Corp Addressable transducer
EP0082080A1 (en) * 1981-12-14 1983-06-22 Etablissement public dit: CHARBONNAGES DE FRANCE Method and apparatus for the transmission of signals, and use in the detection and/or measuring of the concentration of combustible gas in an atmosphere
GB2116764A (en) * 1982-03-11 1983-09-28 Distributed Control Syst Universal input-output device
EP0108903A2 (en) * 1982-11-12 1984-05-23 Dresser Industries,Inc. Universal interface method and apparatus for subsurface earth formation testing

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3631477A1 (en) * 1986-09-16 1988-03-24 Siegfried Schwarz NETWORK FOR DATA AND ENERGY TRANSFER
GB2198569A (en) * 1986-09-16 1988-06-15 Siegfried Schwarz Network for data-and energy transmission
US10746586B2 (en) 2015-05-28 2020-08-18 Sonicu, Llc Tank-in-tank container fill level indicator
US10745263B2 (en) 2015-05-28 2020-08-18 Sonicu, Llc Container fill level indication system using a machine learning algorithm

Also Published As

Publication number Publication date
GB2164180B (en) 1988-03-30
GB8422491D0 (en) 1984-10-10

Similar Documents

Publication Publication Date Title
US6147617A (en) Apparatus and method for detecting faults in outdoor display
US4418424A (en) Cable television transmission control system
US4555930A (en) Digital gas sensing system
EP0618555A2 (en) Smoke type fire detector
GB2127603A (en) Alarm system test circuits
GB2168517B (en) Information transmission system
ATE180099T1 (en) INFORMATION TRANSMISSION SYSTEM AND TRANSMITTERS, RECEIVERS AND RECORDING MEDIUM USED THEREIN
CA2084760A1 (en) Multi-mode input/output circuit and module, and process control system using same
US6172615B1 (en) Communicator for field instruments and method of supplying power to this communicator
GB2116764A (en) Universal input-output device
US3445813A (en) Information transmission system
GB2164180A (en) Remote monitoring apparatus
US5267068A (en) Signal transmission performance evaluation device in an optical communication apparatus
US4494399A (en) Toxic gas detection system calibrator
US4810891A (en) Method for the automatic identification of the type of measuring head of a fiber optic measurement value acquisition and transmission device
GB2289550A (en) Control system for one or more working areas
US5065152A (en) Two-wire loop electric circuit arrangement
US4001703A (en) Transmission line interface circuit
US3922716A (en) Air traffic controller aid
US5015969A (en) Amplifier control system
US4912476A (en) Antenna interface common module
US3796993A (en) Analog input device for data transmission systems
US5208513A (en) Monitoring circuit for a light emission device
US4318110A (en) Multi-channel recording instrument
US4721953A (en) Remote control system

Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19920906