GB2164180A - Remote monitoring apparatus - Google Patents
Remote monitoring apparatus Download PDFInfo
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q9/00—Arrangements 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
-
- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C19/00—Electric signal transmission systems
- G08C19/02—Electric signal transmission systems in which the signal transmitted is magnitude of current or voltage
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q2209/00—Arrangements in telecontrol or telemetry systems
- H04Q2209/80—Arrangements in the sub-station, i.e. sensing device
- H04Q2209/88—Providing 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.
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)
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)
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 |
-
1984
- 1984-09-06 GB GB8422491A patent/GB2164180B/en not_active Expired
Patent Citations (11)
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)
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 |
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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 |