EP0387601A1 - Signalübertragungssystem - Google Patents

Signalübertragungssystem Download PDF

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Publication number
EP0387601A1
EP0387601A1 EP90103820A EP90103820A EP0387601A1 EP 0387601 A1 EP0387601 A1 EP 0387601A1 EP 90103820 A EP90103820 A EP 90103820A EP 90103820 A EP90103820 A EP 90103820A EP 0387601 A1 EP0387601 A1 EP 0387601A1
Authority
EP
European Patent Office
Prior art keywords
current
polarity
transmitter
line
signal
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.)
Withdrawn
Application number
EP90103820A
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German (de)
English (en)
French (fr)
Inventor
Wolfgang Feucht
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.)
Knick Elektronische Messgeraete GmbH and Co KG
Original Assignee
Knick Elektronische Messgeraete GmbH and Co KG
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 Knick Elektronische Messgeraete GmbH and Co KG filed Critical Knick Elektronische Messgeraete GmbH and Co KG
Publication of EP0387601A1 publication Critical patent/EP0387601A1/de
Withdrawn legal-status Critical Current

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    • 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

Definitions

  • the present invention relates to a signal transmission system with a transmitter that sends a current in the range between a predetermined first value and a predetermined second value of the same polarity, in particular between 4 and 20 mA, via a line to at least one receiver.
  • a polarity reversal device is arranged in the line between the transmitter and the receiver, which inverts the polarity of the transmitted current as a function of a signal to be transmitted, and in that at the other end Absolute value generator is arranged, which has an off regardless of the polarity of its input current generated current with a predetermined polarity, wherein the strength of the output current is proportional to the strength of the input current, and has an evaluation device that determines the polarity of the input current.
  • the information of the additionally transmitted signal is therefore in the direction of the current which is transmitted via the line.
  • the absolute value generator always outputs the same current direction at its output and the current always flows in the same direction at the input of the polarity reversal device, the receiver is not subject to the influence of the current direction on the line. In this way, the behavior of the conventional signal transmission system is retained for the receiver and one does not have to prepare it for filtering out any modulated signals.
  • the retrofitting of circuits is possible without intervention in the existing devices. These can continue to work as before.
  • Appropriate coding and subsequent pulse counting in the evaluation unit can also be used to transmit several different signals.
  • the type of signal transmission is mainly suitable for a limited supply of certain signals, for example a warning signal, a switch-off signal, a measuring range exceeded signal or a message request signal.
  • the output current is equal to the input current.
  • the 1: 1 ratio ensures that the operating behavior of the system at the input of the receiver does not differ from that of a conventional system.
  • the absolute value generator is particularly advantageously formed by a rectifier bridge circuit. This is a simple embodiment which can be produced economically and which determines the value of the current practically without inertia. Regardless of the polarity of the current, i.e. the current direction, the current with the same predetermined direction is always output at the output. Only the current strength is influenced by the strength of the input current.
  • the evaluation device can be arranged in front of the absolute value generator. However, it is preferably arranged in a branch of the rectifier bridge circuit.
  • the rectifier bridge circuit has the property that only current in one direction flows in pairs in two branches. If the evaluation device now determines that a current is flowing in the branch in which it is arranged, reliable conclusions can be drawn about the direction of the current in the line.
  • the evaluation device is advantageously formed by a light-emitting diode which, with the same forward direction, lies in series with the diode in the branch of the rectifier bridge circuit.
  • the light emitting diode lights up, which means an optical warning signal for an operator.
  • the state of the light-emitting diode can of course also be tapped via a photo transistor and automatically processed further.
  • An optocoupler is preferably used to minimize the risk of interference from external light. This enables the signal output to be electrically isolated from the current loop.
  • the evaluation device has a resistor, in particular a shunt resistor, and a voltage detection circuit which determines a voltage drop across the resistor.
  • a resistor in particular a shunt resistor
  • a voltage detection circuit which determines a voltage drop across the resistor.
  • a current amplifier or a current / voltage converter which does not cause a voltage drop and has, for example, an operational amplifier can also be used.
  • the voltage determination circuit can have a comparator. This comparator determines whether a voltage across the resistor drops or not. If a voltage drops, this is a sign that the current in the line is flowing in the predetermined direction. Since practically only two voltages can occur, namely the voltage zero and the voltage that corresponds to the product of the flowing current and resistance, and the current must be at least 4 mA, the threshold value limit for the comparator can easily be determined. Furthermore, this need not be overly precise.
  • the rectifier bridge circuit is arranged in the feedback branch of an amplifier with a high amplification factor, in particular an operational amplifier, and the evaluation device is arranged between the output of the amplifier and ground.
  • the polarity of the current in the line ie the direction in which the current flows in the line, can be determined practically without a voltage drop.
  • a capacitor is advantageously arranged at the output of the absolute value generator. This capacitor serves to smooth out the voltage dips that can occur when switching the polarity.
  • the polarity reversing device is preferably designed as a 2-pole reversing switch.
  • This switch can be implemented mechanically or electronically in a simple manner and fulfills the task of inverting the polarity of the current with little effort.
  • the changeover switch can have a relay-operated mechanical switch or can be implemented with semiconductor switches.
  • a mechanical switch can be Carry out signal transmission decoupled from the voltage of the 4 ... 20 mA current.
  • the transmitter is arranged on the same end of the line as the polarity reversal device.
  • the direction of transmission of the signal sent by the transmitter namely the variation of the current strength, and of the signal sent by the polarity reversal device, namely the current direction, is the same.
  • the polarity reversal device and the transmitter are advantageously integrated into one structural unit. This requires only a small additional space.
  • the power supply part in the transmitter for the current source can also be used for the changeover switch.
  • the construction becomes particularly simple if the output stage of the transmitter is bipolar. Then it can be used directly as a switching device.
  • the transmitter is arranged at the end of the line at which the absolute value generator is also arranged.
  • the transmitter is additionally connected to the evaluation device and, after a change in polarity of the current in a predetermined direction, brings about a predetermined change in the strength of the transmission current.
  • the transmitter and the polarity reversal device transmit in opposite directions. This is always advantageous if, for example, the transmitter is removed and is inaccessible for direct checking.
  • the polarity reversal device can send out a status report request signal, upon which the transmitter indicates whether it is OK or not by returning a specific change in current. If the feedback does not correspond to the expected signal, the transmitter is malfunctioning.
  • the absolute value generator is designed so that not only the output current is a function of the input current, but also the input current is dependent on the output current. So if a higher current is caused by the transmitter at the output of the absolute value generator, the current intensity at the input and thus on the line changes accordingly.
  • the request signal is advantageous because it can be used to set the start for a defined state in the system by interpreting the subsequent current change as a status message.
  • the transmitter advantageously falls below the predetermined first current value or exceeds the predetermined second current value for a predetermined period of time. Such exceeding of the transmitter range can be reliably detected.
  • the transmitter effects a current of 21 mA after a change in polarity for a period of about one second.
  • this signal is only generated if the transmitter has a defect or, in another configuration, if it is OK.
  • a signal transmission system has a transmitter 1, which transmits an impressed current in the range between two predetermined values to a receiver 3 via a line 2.
  • the line 2 is designed with two poles, ie it has a path for the current flow from the transmitter 1 to the receiver 3 and a path for the current flow from the receiver 3 to the transmitter 1.
  • the current can vary between 4 and 20 mA.
  • Such a signal is known under the name "Live Zero standard signal”.
  • the transmitter has a current source 4 with a constant, adjustable current output.
  • a polarity reversal device 5 is arranged behind the transmitter 1 and, depending on a signal on an input line 9, inverts the polarity of the current in line 2. Depending on the input signal on the signal input 9, a two-pole changeover switch 7 is actuated, so that the current which was previously conducted on one current path of line 2 is now conducted on the other current path.
  • an absolute value generator 6 is arranged, which has a rectifier bridge circuit.
  • the rectifier bridge circuit has four diodes 11-14 with a low voltage drop, which are arranged in a known manner between an input 10 and an output 15 of the absolute value generator 6.
  • a current with a positive direction flows from input 10 through diode 12 to output 15 and from there to receiver 3.
  • the current from receiver 3 flows via output 15 and diode 13 to input 10 and from there into line 2. If positive Current, therefore, only the diodes 12 and 13 of the rectifier bridge circuit are used.
  • the current flows from the input 10 through the diode 14 to the output 15 and from there to the receiver 3 and on the way back through the output 15 and the diode 11 to the input 10 and to the line 2.
  • the polarity of the current on line 2 is of no importance for the receiver 3. As shown, the current in the receiver 3 always has the same direction.
  • a light-emitting diode 16 is arranged in the branch of the diode 14, ie in the branch in which a current flows only when the current polarity is negative. This light emitting diode 16 has the same forward direction as the diode 14. If a current of negative polarity now flows, the light emitting diode 16 is also passed through and lights up. In order to an optical warning signal is implemented. Of course, the signal from the light-emitting diode can also be picked up by a photo transistor and automatically processed further.
  • a capacitor 22 is arranged, which takes over a buffer function when switching the polarity of the current.
  • FIG. 2 A further embodiment of the signal transmission system is shown in FIG. 2. Elements which are identical to those of FIG. 1 are provided with the same reference symbols, elements which correspond to those of FIG. 1 are provided with reference symbols increased by 100.
  • the transmitter 101 has a current source 104 which generates an impressed current between 4 and 20 mA and sends it to the line 2.
  • the polarity reversing device 105 which has the two-pole reversing switch 7, is integrated in the transmitter 101.
  • the changeover switch 7 is actuated with the aid of a relay 8 as a function of a signal present on the signal line 109.
  • a receiver 3 At the other end of the line, not only a receiver 3 is arranged, but a further receiver 3 'and a recorder 21.
  • further receivers are also possible, each of which responds, for example, only to a predetermined current range.
  • the absolute value generator 106 is constructed similarly to that in FIG. 1. Instead of the light-emitting diode 16, the evaluation device has a resistor 17 through which current flows when a current with negative polarity flows in line 2.
  • the resistor 17 is preferably designed as a shunt resistor, so that the falling voltage can be measured very precisely on it.
  • the falling voltage is examined with the aid of a comparator 18 to determine whether it is above or below a predetermined threshold value. If it is above a predetermined threshold value, a signal appears at signal output 119.
  • This signal can be used, for example, to actuate a relay, which e.g. switches on a signal horn or another consumer with increased power requirements.
  • automatic further processing of the signal at signal output 119 is also possible.
  • the absolute value generator 206 again has a rectifier bridge circuit 211-214, which, however, is in the feedback branch of an operational amplifier 20, i.e. is connected in the branch between the output and inverting input of the operational amplifier 20.
  • the non-inverting input of the operational amplifier is grounded.
  • An active rectifier is thus realized.
  • a signal output 219 can be formed between the output of the operational amplifier and ground, at which a negative voltage is present at input 210 when the current direction is positive and vice versa.
  • FIG. 4 shows a fourth embodiment of the absolute value generator 306.
  • An optocoupler 316 is arranged in the branch of the rectifier bridge circuit in which the diode 314 is arranged.
  • This optocoupler has a light-emitting element 317 and a light-receiving element 318.
  • the light-emitting element 317 is designed as a light-emitting diode, while the light-receiving element Element 318 is a photo transistor. If a current now flows through this branch, the light-emitting diode 317 lights up and changes the properties of the phototransistor 318, so that a signal can be obtained at the output 319.
  • a signal transmission that is potentially decoupled from the 4 to 20 mA current can be realized with it. This considerably simplifies the handling of the signal transmission system.
  • the direction of the signal sent using the varying current strength is the same as the direction of the signal sent using the voltage polarity. In the exemplary embodiment shown in FIG. 5, however, the directions are opposite. Elements which correspond to those in FIG. 1 are provided with reference numerals increased by 400.
  • a voltage source 423 is connected to the polarity reversal device 405 via a current meter 403, which serves as a receiver.
  • the output of the polarity reversal device is connected via line 402 to the input 410 of the absolute value generator 406, to the output 415 of which the transmitter 401 is connected.
  • a second input of the transmitter 401 is connected to the evaluation device 416 via the output 419 of the absolute value generator.
  • the voltage source 423 generates a constant voltage of, for example, 24 V.
  • the transmitter 401 adjusts itself depending on the signal to be transmitted in such a way that a current with the desired current strength in the range between 4 and 20 mA flows in the line 402. For example, if transmitter 401 is removed and is inaccessible for inspection, it is desirable to remotely monitor transmitter 401 to be able to determine the question. For this purpose, the relay 408 is excited, which reverses the polarity reversal device 405. The voltage and current on line 402 are thereby inverted. In contrast, nothing changes at the output 415 of the absolute value generator 406. The polarity of the current is preserved. The current intensity is only influenced by the transmitter 401.
  • the evaluation device 416 generates a signal at the output 419 of the absolute value generator 406, which also goes to the transmitter 401.
  • the transmitter changes its behavior and changes the current strength in a predetermined manner or shows no reaction. For example, it sends a current of 21 mA for one second if it has to indicate a defect. If care is taken to ensure that, before the polarity reversal of the polarity reversal device 405, all elements have been removed or decoupled from the system for which such a current is not desired, the transmission of a 21 mA signal is readily possible. However, it is generally not necessary to disconnect elements, since the elements of the system generally also tolerate higher currents in the order of 30 to 50 mA.
  • the transmitter By sending this signal, the transmitter indicates that it is not in order. If the expected signal is missing, this is a sign that the transmitter is OK and does not need to be checked more closely. Of course, you can also reverse the process and send out the 21 mA signal with the transmitter intact. The absence of the signal then indicates a defect.
  • the receiver 403 is shown as a display instrument.
  • the receiver 403 it is also possible to design the receiver 403 as an evaluation unit, which enables the transmitted measured values to be evaluated automatically.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)
EP90103820A 1989-03-16 1990-02-27 Signalübertragungssystem Withdrawn EP0387601A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19893908558 DE3908558A1 (de) 1989-03-16 1989-03-16 Signaluebertragungssystem
DE3908558 1989-03-16

Publications (1)

Publication Number Publication Date
EP0387601A1 true EP0387601A1 (de) 1990-09-19

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ID=6376455

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90103820A Withdrawn EP0387601A1 (de) 1989-03-16 1990-02-27 Signalübertragungssystem

Country Status (2)

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EP (1) EP0387601A1 (enrdf_load_stackoverflow)
DE (1) DE3908558A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016082952A1 (de) * 2014-11-24 2016-06-02 Continental Teves Ag & Co. Ohg Elektronische anordnung in einem kraftfahrzeug

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4209785C2 (de) * 1992-03-26 1994-04-21 Knick Elektronische Mesgeraete Übertragungssystem für Signale
DE19713981A1 (de) 1997-04-04 1998-10-15 Siemens Ag Vorrichtung zum Zuführen eines analogen und eines digitalen Signals zu einer Recheneinheit und Vorrichtung zur Regelung des Stromflusses durch einen Verbraucher
DE10121879A1 (de) * 2001-05-05 2002-11-07 Conti Temic Microelectronic Verfahren zur Übertragung eines Sensordatensignals und eines Zusatzdatensignals von einer Sensorbaugruppe zu wenigstens einem Empfänger
DE10154002A1 (de) * 2001-11-02 2003-05-22 Siemens Ag Anordnung mit einer peripheren Einheit, die über eine Zweidrahtleitung einer zentralen Einheit angeschlossen ist
DE10322262B4 (de) * 2003-05-16 2006-05-04 Knick Elektronische Messgeräte GmbH & Co. KG Signal-Speisetrenner für Messsignale
DE102012007417A1 (de) 2012-04-16 2013-10-17 Festo Ag & Co. Kg Sensormodul
DE102012218429A1 (de) 2012-10-10 2014-04-10 Zumtobel Lighting Gmbh System zur Funktionsüberwachung einer Stromschleife

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH319429A (de) * 1952-11-06 1957-02-15 Asea Ab Verfahren und Anordnung zur gleichzeitigen Intensitätsmessung und Impulssendung über die gleiche Übertragungsleitung
US4511896A (en) * 1982-07-30 1985-04-16 The United States Of America As Represented By The Secretary Of The Army Remote sensor system with bi-directional monitoring and control of operation
EP0244808A1 (de) * 1986-05-07 1987-11-11 Endress u. Hauser GmbH u. Co. Anordnung zur Signalübertragung in einer Messanordnung

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0101528B1 (en) * 1982-08-19 1989-11-08 Honeywell Inc. Improvements in 2-wire analog communication systems
US4691328A (en) * 1985-08-12 1987-09-01 The Babcock & Wilcox Company On-line serial communication interface from a computer to a current loop

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH319429A (de) * 1952-11-06 1957-02-15 Asea Ab Verfahren und Anordnung zur gleichzeitigen Intensitätsmessung und Impulssendung über die gleiche Übertragungsleitung
US4511896A (en) * 1982-07-30 1985-04-16 The United States Of America As Represented By The Secretary Of The Army Remote sensor system with bi-directional monitoring and control of operation
EP0244808A1 (de) * 1986-05-07 1987-11-11 Endress u. Hauser GmbH u. Co. Anordnung zur Signalübertragung in einer Messanordnung

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016082952A1 (de) * 2014-11-24 2016-06-02 Continental Teves Ag & Co. Ohg Elektronische anordnung in einem kraftfahrzeug
KR20170072313A (ko) * 2014-11-24 2017-06-26 콘티넨탈 테베스 아게 운트 코. 오하게 모터 차량에서의 전자 장치
CN107003146A (zh) * 2014-11-24 2017-08-01 大陆-特韦斯贸易合伙股份公司及两合公司 机动车中的电子装置
KR101941800B1 (ko) 2014-11-24 2019-01-23 콘티넨탈 테베스 아게 운트 코. 오하게 모터 차량에서의 전자 장치
US10345334B2 (en) 2014-11-24 2019-07-09 Continental Teves Ag & Co. Ohg Electronic arrangement in a motor vehicle
CN107003146B (zh) * 2014-11-24 2019-12-10 大陆-特韦斯贸易合伙股份公司及两合公司 机动车中的电子装置

Also Published As

Publication number Publication date
DE3908558C2 (enrdf_load_stackoverflow) 1990-12-20
DE3908558A1 (de) 1990-09-20

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