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EP0809222A1 - Apparatus for data transfer in process control systems - Google Patents

Apparatus for data transfer in process control systems Download PDF

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Publication number
EP0809222A1
EP0809222A1 EP97250159A EP97250159A EP0809222A1 EP 0809222 A1 EP0809222 A1 EP 0809222A1 EP 97250159 A EP97250159 A EP 97250159A EP 97250159 A EP97250159 A EP 97250159A EP 0809222 A1 EP0809222 A1 EP 0809222A1
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Prior art keywords
field
transformer
data bus
field device
coupling means
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EP97250159A
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German (de)
French (fr)
Inventor
Günter Dipl.-Ing. von zur Gathen
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ABB Training Center GmbH and Co KG
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Hartmann and Braun AG
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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 invention relates to an arrangement for data transmission in process control systems, such as are used in process engineering.
  • each measured value or manipulated value is converted into a proportional direct current, which is superimposed on the direct feed current, wherein the direct current presenting the measured value or manipulated value can be a multiple of the direct feed current.
  • the supply current requirement of the field device is usually set to approx. 4 mA and the dynamic range of the measured value or control value is mapped to currents between 0 and 16 mA, so that the known 4 ... 20 mA current loop can be used.
  • the circuits for the measured value acquisition and the measured value processing are predominantly galvanically separated from one another.
  • Newer field devices are also characterized by universal properties that are largely adaptable to the respective process.
  • a bidirectionally operable alternating current transmission path is provided, via which parameterization data are transmitted in the direction of the field device and measured values and status data are transmitted from the direction of the field device.
  • the parameterization data and the measured values as well as the status data are modulated onto an AC voltage, preferably frequency-modulated.
  • field devices In process control engineering, it is customary to arrange and link field devices in the so-called field area, i.e. measuring, actuating and display modules, in accordance with the specified safety conditions on site. These field devices have analog and digital interfaces with each other for data transmission. The data transmission is carried out via the feed lines of the power supply arranged in the waiting area. For remote control and remote diagnosis of these field devices, control devices are also provided in the so-called waiting area, the security requirements of which are generally subject to lower requirements.
  • the data transmission between the operating devices in the control room and the field devices is realized by superimposing the known 20 mA current loops with the help of FSK modulation (frequency shift keying). Two frequencies, which are assigned to the binary states "0" and "1", are transmitted analogously in frames.
  • the first network topology concerns a point-to-point connection. Only one field device can be connected to each operating device. The field device allows both analog and digital transmission.
  • the second network topology relates to a bus structure in which a plurality of field devices can be connected to an operating device via a common bus. Only digital data transmission is permitted. Due to the definition of parameters, the maximum number of field devices that can be connected to a bus is limited to 15 and the maximum length of the bus to approximately 3300 m.
  • a key component of these definition parameters is the internal resistance of the power supply devices assigned to the field devices.
  • the internal resistance of the voltage source is connected in parallel with the input resistance of the respective receiver circuit, so that the resulting terminating resistance from the transmission direction is also almost zero. Communication is therefore only possible if a sufficiently large impedance for modulation is provided.
  • the invention is based on the object, while maintaining the direct current transmission path between a control device and a field device, to network a large number of field devices with the least possible effort for bidirectional AC communication with an operating device via a serial data bus.
  • FIG. 1 shows a block diagram of an arrangement for data exchange in a process control system.
  • the invention is based on a field device 10 which is connected to a control device 30 via a coupling means 20.
  • the coupling means 20 is designed for the electrical isolation of the circuit from the control device 30 from the circuit of the field device 10.
  • the 4 ... 20 mA current loop known per se is used for direct current transmission from control device 30 to field device 10.
  • the communication between the control device 30 and the field device 10 is unidirectional in relation to the direct current transmission.
  • the 4... 20 mA current loop represents the recorded measured value, which is transmitted to the control device 30.
  • the 4 ... 20 mA current loop is fed by the control device 30 and represents the control value to be set on the field device 10.
  • the coupling means 20 has a chain connection comprising an inverter, a transformer and a rectifier, the inverter being connected to the driven current loop and the rectifier being connected to the driving current loop.
  • Coupling means 20 of this type are known per se and are described in detail, for example, in DE 43 43 450.
  • the operating device 50 can be designed as a personal computer 51 known per se with a connected modem 52.
  • the coupling means 20 has a separate alternating current transformer 21, the windings of which are traversed by the driving and driven current of the coming and going 4 ... 20 mA current loops. It is provided that the current strengths of the driving and driven direct currents are exactly identical in terms of magnitude and directed in opposite directions with respect to the through-flow of the alternating current transformer 21, so that the alternating current transformer 21 is compensated for direct current. In addition, it is provided to build the AC transformer 21 with a core made of highly permeable material.
  • the saturation of the core is avoided even in the smallest designs of the AC transformer 21, despite the highly permeable core material, but the AC impedance of the transformer 21, which represents the input resistance for the bidirectional AC signal, is increased to such an extent that an AC parallel connection of several coupling means 20 is observed the level and impedance limit values for the FSK signal used for AC transmission according to the HART protocol are made possible without amplifier means.
  • the data bus 70 is connected to each coupling means 20 on the control unit side via an attenuator 40 which has at least one capacitive switching element. It is provided that the AC circuit of the data bus 70 via the series connection from the internal resistance of the respective DC receiver 20th or 30 and the control unit-side winding of the transformer 21 is closed.
  • the control device 30 is the receiver of the unidirectional direct current and the input resistance of the control device 30 is connected in series with the control device-side winding of the transformer 21 with respect to the AC circuit of the data bus 70.
  • the coupling means 20 is the receiver of the unidirectional direct current fed in by the control device 30 and the input resistance of the coupling means 20 is connected in series with the control unit-side winding of the transmitter 21 with respect to the AC circuit of the data bus 70.
  • the number of coupling means 20 that can be connected to a data bus 70 via an attenuator 40 depends on the design of the AC transformer 21, taking into account the total impedance resulting from the parallel connection of the individual AC impedances with respect to the impedance limit specified by the HART protocol.
  • the data bus 70 is connected to the modem 52 of the operating device 50.
  • each attenuator 40 according to FIG. 3 consists of a chain circuit in a line consisting of a resistor and a capacitor.
  • the data bus 70 is segmented by active bus couplers 60.
  • the modem 52 of the operating device 50 is connected to a plurality of such bus couplers 60, each of which is followed by a maximum, predeterminable number of attenuators 40 for connection to coupling means 20.
  • Such a bus coupler 60 is described in detail in DE 42 32 922.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

The apparatus uses FSK modulation between field devices (10) and a control device (30) connected to a serial data bus (70). Each field device is connected via a coupler (20) with a transformer (21) for a.c. transformation to a controller in parallel with a unidirectional d.c. communications path between the controller and field device. The coupler's transformer is d.c. compensated and has a high permeability core. The serial data bus is connected to the coupler for each field device via a damping element (40) with at least one capacitive switching device, so that the data bus a.c. circuit is completed by the series circuit contg. the d.c. receiver's internal impedance and the transformer coil on the control side.

Description

Die Erfindung betrifft eine Anordnung zur Datenübertragung in Prozeßleitsystemen, wie sie in der Verfahrenstechnik angewendet werden.The invention relates to an arrangement for data transmission in process control systems, such as are used in process engineering.

In der Meß-, Steuerungs- und Regelungstechnik ist es seit längerem üblich, über eine Zweitdrahtleitung ein Feldgerät zu speisen und Meßwerte von diesem Feldgerät zu einem Anzeigegerät und/oder zu einer regelungstechnischen Anlage beziehungsweise Stellwerte von einer regelungstechnischen Anlage zum Feldgerät zu übertragen. Dabei wird jeder Meßwert beziehungsweise Stellwert in einen proportionalen Gleichstrom umgeformt, der dem Speisegleichstrom überlagert wird, wobei der den Meßwert beziehungsweise Stellwert präsentierende Gleichstrom ein Vielfaches des Speisegleichstroms sein kann. So ist üblicherweise der Speisestrombedarf des Feldgerätes auf ca. 4 mA eingestellt und der Dynamikumfang des Meßwertes beziehungsweise Stellwertes auf Ströme zwischen 0 und 16 mA abgebildet, so daß die bekannte 4...20 mA-Stromschleife verwendbar ist.In measurement, control and regulation technology, it has long been customary to feed a field device via a second wire line and to transmit measured values from this field device to a display device and / or to a control system or control values from a control system to the field device. Each measured value or manipulated value is converted into a proportional direct current, which is superimposed on the direct feed current, wherein the direct current presenting the measured value or manipulated value can be a multiple of the direct feed current. For example, the supply current requirement of the field device is usually set to approx. 4 mA and the dynamic range of the measured value or control value is mapped to currents between 0 and 16 mA, so that the known 4 ... 20 mA current loop can be used.

Zur Vermeidung von Meßwertverfälschungen infolge Potentialverschleppung und aus sicherheitstechnischen Gründen sind die Stromkreise für die Meßwerterfassung und die Meßwertverarbeitung überwiegend galvanisch voneinander getrennt ausgeführt.In order to avoid falsification of measured values as a result of potential carryover and for safety reasons, the circuits for the measured value acquisition and the measured value processing are predominantly galvanically separated from one another.

Neuere Feldgeräte zeichnen sich darüber hinaus durch universelle, weitgehend an den jeweiligen Prozeß adaptierbare Eigenschaften aus. Dazu ist parallel zum unidirektionalen Gleichstromübertragungsweg ein bidirektional betreibbarer Wechselstromübertragungsweg vorgesehen, über den in Richtung zum Feldgerät Parametrierdaten und aus Richtung des Feldgerätes Meßwerte und Zustandsdaten übertragen werden. Die Parametrierdaten und die Meßwerte sowie die Zustandsdaten sind auf eine Wechselspannung moduliert, vorzugsweise frequenzmoduliert.Newer field devices are also characterized by universal properties that are largely adaptable to the respective process. For this purpose, parallel to the unidirectional direct current transmission path, a bidirectionally operable alternating current transmission path is provided, via which parameterization data are transmitted in the direction of the field device and measured values and status data are transmitted from the direction of the field device. The parameterization data and the measured values as well as the status data are modulated onto an AC voltage, preferably frequency-modulated.

In der Prozeßleittechnik ist es üblich, im sogenannten Feldbereich Feldgeräte, das sind Meß-, Stell- und Anzeigebaugruppen, entsprechend den vorgegebenen Sicherheitsbedingungen vor Ort anzuordnen und zu verknüpfen. Diese Feldgeräte weisen zur Datenübertragung untereinander analoge und digitale Schnittstellen auf. Die Datenübertragung wird dabei über die Speiseleitungen der im Wartenbereich angeordneten Stromversorgung vorgenommen. Zur Fernsteuerung und Ferndiagnose dieser Feldgeräte sind auch Bediengeräte in dem sogenannten Wartenbereich vorgesehen, an dessen Sicherheitsbestimmungen regelmäßig geringere Anforderungen gestellt sind.In process control engineering, it is customary to arrange and link field devices in the so-called field area, i.e. measuring, actuating and display modules, in accordance with the specified safety conditions on site. These field devices have analog and digital interfaces with each other for data transmission. The data transmission is carried out via the feed lines of the power supply arranged in the waiting area. For remote control and remote diagnosis of these field devices, control devices are also provided in the so-called waiting area, the security requirements of which are generally subject to lower requirements.

Die Datenübertragung zwischen den Bediengeräten im Wartenbereich und den Feldgeräten wird durch Überlagerung der bekannten 20 mA-Stromschleifen mit Hilfe der der FSK-Modulation (Frequenz Shift Keying) realisiert. Dabei werden zwei Frequenzen, die den binären Zuständen "0" und "1" zugeordnet sind, rahmenweise analog übertragen.The data transmission between the operating devices in the control room and the field devices is realized by superimposing the known 20 mA current loops with the help of FSK modulation (frequency shift keying). Two frequencies, which are assigned to the binary states "0" and "1", are transmitted analogously in frames.

Die Rahmenbedingungen für das FSK-Signal und die Art der Modulation sind in der "HART Physical Layer Specification Revision 7.1-Final" vom 20.06.1990 (Rosemount Dokument Nr. D8900097; Revision B) beschrieben. In dieser Veröffentlichung sind darüber hinaus zwei grundlegende Netzwerktopologien zur Verknüpfung von Feldgeräten mit Bediengeräten angegeben.The framework conditions for the FSK signal and the type of modulation are described in the "HART Physical Layer Specification Revision 7.1-Final" from June 20, 1990 (Rosemount Document No. D8900097; Revision B). This publication also specifies two basic network topologies for linking field devices with operator panels.

Die erste Netzwerktopologie betrifft eine Punkt-zu-Punkt-Verbindung. Dabei ist an jedes Bediengerät nur ein Feldgerät anschaltbar. Durch das Feldgerät ist sowohl analoge wie digitale Übertragung zugelassen.The first network topology concerns a point-to-point connection. Only one field device can be connected to each operating device. The field device allows both analog and digital transmission.

Die zweite Netzwerktopologie betrifft eine Busstruktur, bei der eine Mehrzahl von Feldgeräten über einen gemeinsamen Bus an ein Bediengerät anschaltbar sind. Dabei ist ausschließlich die digitale Datenübertragung zugelassen. Aufgrund definitionsgemäßer Parametervorgaben ist die maximale Anzahl der an einen Bus anschaltbaren Feldgeräte auf 15 und die maximale Länge des Busses auf etwa 3300 m beschränkt.The second network topology relates to a bus structure in which a plurality of field devices can be connected to an operating device via a common bus. Only digital data transmission is permitted. Due to the definition of parameters, the maximum number of field devices that can be connected to a bus is limited to 15 and the maximum length of the bus to approximately 3300 m.

Entscheidender Bestandteil dieser definitionsgemäßen Parametervorgaben ist der Innenwiderstand der den Feldgeräten zugeordneten Stromversorgungseinrichtungen.A key component of these definition parameters is the internal resistance of the power supply devices assigned to the field devices.

Feldgeräte werden in der Regel mit einer stabilen und geglätteten Versorgungsgleichspannung gespeist. Der Innenwiderstand einer diesen Anforderungen genügenden Spannungsquelle ist nahezu Null.As a rule, field devices are supplied with a stable and smoothed DC supply voltage. The internal resistance of a voltage source that meets these requirements is almost zero.

Da die Speiseleitungen der Stromversorgung zu den Feldgeräten auch für die Datenübertragung benutzt werden, ist der Innenwiderstand der Spannungsquelle dem Eingangswiderstand der jeweiligen Empfängerschaltung parallel geschaltet, so daß der resultierende Abschlußwiderstand aus Senderichtung ebenfalls nahezu Null ist. Eine Kommunikation ist daher nur möglich, wenn eine ausreichend große lmpedanz zur Modulation vorgesehen wird.Since the feed lines of the power supply to the field devices are also used for data transmission, the internal resistance of the voltage source is connected in parallel with the input resistance of the respective receiver circuit, so that the resulting terminating resistance from the transmission direction is also almost zero. Communication is therefore only possible if a sufficiently large impedance for modulation is provided.

Aus der DE 43 43 540 ist eine Anordnung zur potentialgetrennten Übertragung von Gleich- und Wechselstromsignalen über Zweidrahtleitungen bekannt, die aus einem Wechselrichter einer Koppelstufe mit galvanischer Trennung und einem Gleichrichter zur unidirektionalen Gleichstromübertragung und einem Übertrager zur Wechselstromübertragung besteht, wobei dem Wechselrichter eine erste Reiheninduktivität vorgeschaltet ist, dem Gleichrichter eine zweite Reiheninduktivität nachgeschaltet ist und die erste und die zweite Reiheninduktivität Wicklungen des Übertragers zur Wechselstromübertragung sind. Dieser Anordnung sind Mittel zur Stromversorgung zuordnenbar, die eine impedanzmäßig angepaßte Speisung des jeweilig angeschlossenen Feldgeräts erlaubt.From DE 43 43 540 an arrangement for the isolated transmission of direct and alternating current signals via two-wire lines is known, which consists of an inverter of a coupling stage with electrical isolation and a rectifier for unidirectional direct current transmission and a transformer for alternating current transmission, the inverter being connected upstream of a first series inductance is, the rectifier is followed by a second series inductor and the first and second series inductors are windings of the transformer for AC transmission. Means for power supply can be assigned to this arrangement, which allow an impedance-adapted supply of the respectively connected field device.

Um darüber hinaus Daten zwischen einem Bediengerät und dem Feldgerät mittels FSK-moduliertem Wechselstrom austauschen zu können, ist aus der DE 42 32 922 bekannt, Feldgeräte über einen Buskoppler an den Datenbus anzuschließen, der bidirektional ausgelegt ist und in Sende- und Empfangsrichtung identische Bauteile in identischer Reihenfolge aufweist, wobei während der Datenübertragung ausschließlich die der jeweiligen Übertragungsrichtung zugeordneten Bauteile angeschlossen sind. Zur Impedanzanpassung ist dabei dem Speisegerät ein Serienwiderstand nachgeschaltet. Aufgrund der lmpedanzverhältnisse ist jedoch für jedes Feldgerät ein separater Buskoppler erforderlich, so daß bei einer Vielzahl von Feldgeräten der Aufwand für die Buskoppler sehr groß ist.In order to also be able to exchange data between an operating device and the field device by means of FSK-modulated alternating current, it is known from DE 42 32 922 to connect field devices to the data bus via a bus coupler, which is designed bidirectionally and has identical components in the send and receive direction Identical order, wherein only the components assigned to the respective direction of transmission are connected during data transmission. A series resistor is connected downstream of the supply unit for impedance matching. Because of the impedance conditions, however, a separate bus coupler is required for each field device, so that the bus couplers are very expensive in a large number of field devices.

Der Erfindung liegt die Aufgabe zugrunde, unter Erhalt des Gleichstomübertragungsweges zwischen einem Steuergerät und einem Feldgerät, eine Vielzahl von Feldgeräten mit möglichst geringem Aufwand zur bidirektionalen Wechselstromkommunikation mit einem Bediengerät über einen seriellen Datenbus zu vernetzen.The invention is based on the object, while maintaining the direct current transmission path between a control device and a field device, to network a large number of field devices with the least possible effort for bidirectional AC communication with an operating device via a serial data bus.

Erfindungsgemäß wird diese Aufgabe mit den Mitteln des Patentanspruchs 1 gelöst. Vorteilhafte Ausgestaltungen der Erfindung sind in den Patentansprüchen 2 und 3 beschrieben.According to the invention, this object is achieved with the means of claim 1. Advantageous embodiments of the invention are described in claims 2 and 3.

Die Erfindung wird nachstehend anhand von Ausführungsbeispielen näher erläutert. Die dazu erforderlichen Zeichnungen zeigen:

Figur 1
ein Blockschaltbild einer Anordnung zur Datenübertragung
Figur 2
ein Blockschaltbild einer erweiterten Anordnung zur Datenübertragung
Figur 3
eine Detaildarstellung eines Dämpfungsgliedes.
The invention is explained in more detail below on the basis of exemplary embodiments. The necessary drawings show:
Figure 1
a block diagram of an arrangement for data transmission
Figure 2
a block diagram of an extended arrangement for data transmission
Figure 3
a detailed view of an attenuator.

In Figur 1 ist ein Blockschaltbild einer Anordnung zum Datenaustausch in einem Prozeßleitsystem dargestellt. Die Erfindung geht dabei von einem Feldgerät 10 aus, das über ein Koppelmittel 20 mit einem Steuergerät 30 verbunden ist. Dabei ist das Koppelmittel 20 zur galvanischen Trennung des Stromkreises vom Steuergerät 30 vom Stromkreis des Feldgerätes 10 ausgeführt.FIG. 1 shows a block diagram of an arrangement for data exchange in a process control system. The invention is based on a field device 10 which is connected to a control device 30 via a coupling means 20. The coupling means 20 is designed for the electrical isolation of the circuit from the control device 30 from the circuit of the field device 10.

Zur Gleichstromübertragung vom Steuergerät 30 zum Feldgerät 10 wird die für sich bekannte 4...20mA-Stromschleife verwendet. Die Kommunikation zwischen dem Steuergerät 30 und dem Feldgerät 10 ist bezogen auf die Gleichstromübertragung unidirektional. Soweit das Feldgerät 10 ein Meßwertaufnehmer ist, repräsentiert die 4...20mA-Stromschleife den aufgenommenen Meßwert, der zum Steuergerät 30 übertragen wird. Wenn das Feldgerät 10 als Stellglied ausgeführt ist, wird die 4...20mA-Stromschleife vom Steuergerät 30 gespeist und repräsentiert den am Feldgerät 10 einzustellenden Stellwert.The 4 ... 20 mA current loop known per se is used for direct current transmission from control device 30 to field device 10. The communication between the control device 30 and the field device 10 is unidirectional in relation to the direct current transmission. Insofar as the field device 10 is a measured value pickup, the 4... 20 mA current loop represents the recorded measured value, which is transmitted to the control device 30. If the field device 10 is designed as an actuator, the 4 ... 20 mA current loop is fed by the control device 30 and represents the control value to be set on the field device 10.

Zur galvanischen Trennung des Gleichstromes der 4...20mA-Stromschleife weist das Koppelmittel 20 eine Kettenschaltung aus einem Wechselrichter, einem Übertrager und einem Gleichrichter auf, wobei der Wechselrichter jeweils in die getriebene Stromschleife und der Gleichrichter in die treibende Stromschleife geschaltet ist.For the galvanic separation of the direct current of the 4 ... 20mA current loop, the coupling means 20 has a chain connection comprising an inverter, a transformer and a rectifier, the inverter being connected to the driven current loop and the rectifier being connected to the driving current loop.

Derartige Koppelmittel 20 sind für sich bekannt und beispielsweise in der DE 43 43 450 ausführlich beschrieben.Coupling means 20 of this type are known per se and are described in detail, for example, in DE 43 43 450.

Parallel zu diesem unidirektionalen Gleichstromübertragungsweg ist ein gleichfalls galvanisch getrennter, jedoch bidirektionaler Wechselstromübertragungsweg zum Feldgerät 10 vorgesehen, über den Parametrierdaten zum Feldgerät 10 und Diagnosedaten vom Feldgerät 10 zu einem Bediengerät 50 übertragen werden.Parallel to this unidirectional direct current transmission path, there is also a galvanically separated, but bidirectional, alternating current transmission path to the field device 10, via which parameterization data for the field device 10 and diagnostic data are transmitted from the field device 10 to an operating device 50.

Das Bediengerät 50 kann dabei als für sich bekannter Personalcomputer 51 mit angeschlossenem Modem 52 ausgeführt sein.The operating device 50 can be designed as a personal computer 51 known per se with a connected modem 52.

Zur galvanisch getrennten Übertragung des Wechselstromsignals weist das Koppelmittel 20 einen separaten Wechselstromübertrager 21 auf, dessen Wicklungen vom treibenden und getriebenen Strom der kommenden und gehenden 4...20mA-Stromschleifen durchflossen sind. Dabei ist vorgesehen, daß die Stromstärken des treibenden und des getriebenen Gleichstromes betragsmäßig exakt identisch und bezogen auf die Durchflutung des Wechselstromübertragers 21 entgegengesetzt gerichtet sind, so daß der Wechselstromübertrager 21 gleichstromkompensiert ist. Darüber hinaus ist vorgesehen, den Wechselstromübertrager 21 mit einem Kern aus hochpermeablem Werkstoff aufzubauen.For the galvanically isolated transmission of the alternating current signal, the coupling means 20 has a separate alternating current transformer 21, the windings of which are traversed by the driving and driven current of the coming and going 4 ... 20 mA current loops. It is provided that the current strengths of the driving and driven direct currents are exactly identical in terms of magnitude and directed in opposite directions with respect to the through-flow of the alternating current transformer 21, so that the alternating current transformer 21 is compensated for direct current. In addition, it is provided to build the AC transformer 21 with a core made of highly permeable material.

Durch die vorgesehene Gleichstromkompensation wird dabei auch bei kleinsten Bauformen des Wechselstromübertragers 21 trotz hochpermeablem Kernwerkstoffes die Sättigung des Kerns vermieden, jedoch die Wechselstromimpedanz des Übertragers 21, die den Eingangswiderstand für das bidirektionale Wechselstromsignal darstellt, soweit erhöht, daß eine wechselspannungsmäßige Parallelschaltung mehrerer Koppelmittel 20 unter Einhaltung der Pegel- und Impedanzgrenzwerte für das zur Wechselstromübertragung verwendete FSK-Signal gemäß HART-Protokoll ohne Verstärkermittel ermöglicht wird.Due to the DC compensation provided, the saturation of the core is avoided even in the smallest designs of the AC transformer 21, despite the highly permeable core material, but the AC impedance of the transformer 21, which represents the input resistance for the bidirectional AC signal, is increased to such an extent that an AC parallel connection of several coupling means 20 is observed the level and impedance limit values for the FSK signal used for AC transmission according to the HART protocol are made possible without amplifier means.

Zur Parallelschaltung mehrerer Koppelmittel 20 an einen Datenbus 70 ist der Datenbus 70 jeweils über ein Dämpfungsglied 40, das mindestens ein kapazitives Schaltelement aufweist, steuergeräteseitig an jedes Koppelmittel 20 angeschlossen. Dabei ist vorgesehen, daß der Wechselstromkreis des Datenbusses 70 über die Reihenschaltung aus dem Innenwiderstand des jeweiligen Gleichstromempfängers 20 oder 30 und der steuergeräteseitige Wicklung des Übertragers 21 geschlossen ist. Soweit das Feldgerät 10 ein Meßwertaufnehmer ist, ist das Steuergerät 30 Empfänger des unidirektionalen Gleichstroms und der Eingangswiderstand des Steuergeräts 30 ist bezüglich des Wechselstromkreises des Datenbusses 70 mit der steuergeräteseitigen Wicklung des Übertragers 21 in Reihe geschaltet. Wenn das Feldgerät 10 als Stellglied ausgeführt ist, ist das Koppelmittel 20 Empfänger des vom Steuergerät 30 eingespeisten unidirektionalen Gleichstroms und der Eingangswiderstand des Koppelmittels 20 ist bezüglich des Wechselstromkreises des Datenbusses 70 mit der steuergeräteseitigen Wicklung des Übertragers 21 in Reihe geschaltet.To connect several coupling means 20 in parallel to a data bus 70, the data bus 70 is connected to each coupling means 20 on the control unit side via an attenuator 40 which has at least one capacitive switching element. It is provided that the AC circuit of the data bus 70 via the series connection from the internal resistance of the respective DC receiver 20th or 30 and the control unit-side winding of the transformer 21 is closed. As far as the field device 10 is a transducer, the control device 30 is the receiver of the unidirectional direct current and the input resistance of the control device 30 is connected in series with the control device-side winding of the transformer 21 with respect to the AC circuit of the data bus 70. If the field device 10 is designed as an actuator, the coupling means 20 is the receiver of the unidirectional direct current fed in by the control device 30 and the input resistance of the coupling means 20 is connected in series with the control unit-side winding of the transmitter 21 with respect to the AC circuit of the data bus 70.

Die Anzahl der an einen Datenbus 70 über jeweils ein Dämpfungsglied 40 anschaltbaren Koppelmittel 20 richtet sich dabei nach der konstruktiven Ausgestaltung des Wechselstromübertragers 21 unter Berücksichtigung der sich durch die Parallelschaltung der einzelnen Wechselstromimpedanzen ergebenden Gesamtimpedanz in Bezug auf den durch das HART-Protokoll vorgegebenen Impedanzgrenrwert. Der Datenbus 70 ist an das Modem 52 des Bediengeräts 50 angeschlossen.The number of coupling means 20 that can be connected to a data bus 70 via an attenuator 40 depends on the design of the AC transformer 21, taking into account the total impedance resulting from the parallel connection of the individual AC impedances with respect to the impedance limit specified by the HART protocol. The data bus 70 is connected to the modem 52 of the operating device 50.

In Ausgestaltung der Erfindung ist vorgesehen, daß jedes Dämpfungsglied 40 gemäß Figur 3 aus einer in einer Leitung liegenden Kettenschaltung aus einem Widerstand und einem Kondensator besteht.In an embodiment of the invention, it is provided that each attenuator 40 according to FIG. 3 consists of a chain circuit in a line consisting of a resistor and a capacitor.

In weiterer Ausgestaltung der Erfindung ist vorgesehen, zur Vervielfachung der mittels eines Bediengeräts 50 bedienbaren Feldgeräte 10 den Datenbus 70 durch aktive Buskoppler 60 zu segmentieren. Dabei ist das Modem 52 des Bediengeräts 50 mit einer Mehrzahl derartiger Buskoppler 60 verbunden, denen jeweils eine maximale vorgebbare Anzahl von Dämpfungsgliedern 40 zur Verbindung mit Koppelmitteln 20 nachgeschaltet sind. Ein derartiger Buskoppler 60 ist in der DE 42 32 922 detailliert beschrieben.In a further embodiment of the invention, in order to multiply the field devices 10 which can be operated by means of an operating device 50, the data bus 70 is segmented by active bus couplers 60. The modem 52 of the operating device 50 is connected to a plurality of such bus couplers 60, each of which is followed by a maximum, predeterminable number of attenuators 40 for connection to coupling means 20. Such a bus coupler 60 is described in detail in DE 42 32 922.

Die Beschreibungen aus den DE 43 43 540 und DE 42 32 922 sind Gegenstand dieser Offenbarung.The descriptions from DE 43 43 540 and DE 42 32 922 are the subject of this disclosure.

Auf diese Weise ist eine Vielzahl von Feldgeräten 10 mit geringem Aufwand durch ein einziges Bediengerät 50 bedienbar und vorteilhaft vernetzbar.In this way, a large number of field devices 10 can be operated and advantageously networked with little effort by a single operating device 50.

BezugszeichenlisteReference list

1010th
FeldgerätField device
2020th
KoppelmittelCoupling agent
2121
ÜbertragerTransformer
3030th
SteuergerätControl unit
4040
DämpfungsgliedAttenuator
5050
BediengerätControl unit
5151
PersonalcomputerPersonal computer
5252
Modemmodem
6060
BuskopplerBus coupler
7070
DatenbusData bus

Claims (3)

Anordnung zur Datenübertragung mittels FSK-Modulation in Prozeßleitsystemen zwischen im Feldbereich angeordneten Feldgeräten und einem im Wartenbereich angeordneten Bediengerät, das an einen seriellen Datenbus angeschlossen ist, wobei jedes Feldgerät über ein Koppelmittel, das zur Wechselstromübertragung einen Übertrager aufweist, mit einem Steuergerät verbunden ist, parallel zu einem unidirektionalen Gleichstromübertragungsweg zwischen dem Steuergerät und dem Feldgerät
dadurch gekennzeichnet - daß der Übertrager (21) des Koppelmittels (20) gleichstromkompensiert ist, - daß das Kernmaterial des Übertragers (21) hochpermeabel ist und - daß der serielle Datenbus (70) für jedes Feldgerät (10) über ein mindestens ein kapazitives Schaltelement aufweisendes Dämpfungsglied (40) steuergeräteseitig an dem Koppelmittel (20) derart aufgeschaltet ist, daß der Wechselstromkreis des Datenbusses (70) über die Reihenschaltung aus dem Innenwiderstand des Gleichstromempfängers (20, 30) und der steuergeräteseitige Wicklung des Übertragers (21) geschlossen ist. Arrangement for data transmission by means of FSK modulation in process control systems between field devices arranged in the field area and an operating device arranged in the waiting area, which is connected to a serial data bus, each field device being connected in parallel to a control device via a coupling means which has a transmitter for alternating current transmission to a unidirectional direct current transmission path between the control device and the field device
characterized - That the transformer (21) of the coupling means (20) is DC-compensated, - That the core material of the transmitter (21) is highly permeable and - That the serial data bus (70) for each field device (10) via an at least one capacitive switching element having attenuator (40) on the control device side is connected to the coupling means (20) such that the AC circuit of the data bus (70) via the series circuit from the internal resistance of the DC receiver (20, 30) and the control unit-side winding of the transformer (21) is closed. Anordnung nach Anspruch 1
dadurch gekennzeichnet,
daß das Dämpfungsglied (40) eine in einer Linie liegende Kettenschaltung aus einem Widerstand und einem Kondensator umfaßt.Arrangement according to claim 1
characterized,
that the attenuator (40) comprises an in-line chain circuit comprising a resistor and a capacitor. Anordnung nach einem der Ansprüche 1 und 2
dadurch gekennzeichnet,
daß zwischen Dämpfungsgliedern (40) und dem Bediengerät (50) mindestens ein aktiver Buskoppler (60) vorgesehen ist, daß jedem Buskoppler (60) eine maximale vorgebbare Anzahl Dämpfungsglieder (40) nachgeschaltet ist.Arrangement according to one of claims 1 and 2
characterized,
that at least one active bus coupler (60) is provided between attenuators (40) and the operating device (50), that a maximum predeterminable number of attenuators (40) is connected downstream of each bus coupler (60).
EP97250159A 1996-05-22 1997-05-22 Apparatus for data transfer in process control systems Withdrawn EP0809222A1 (en)

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DE1996122295 DE19622295A1 (en) 1996-05-22 1996-05-22 Arrangement for data transmission in process control systems
DE19622295 1996-05-22

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008052877A1 (en) 2006-10-31 2008-05-08 Endress+Hauser Gmbh + Co. Kg System for determining and/or monitoring at least one process quantity
WO2008061935A1 (en) * 2006-11-22 2008-05-29 Endress+Hauser Wetzer Gmbh+Co. Kg Signal isolation unit for a dual-conductor process control loop
CN103471637A (en) * 2004-03-29 2013-12-25 罗斯蒙德公司 Two wire transmitter with isolated CAN output
EP2701018A1 (en) * 2012-08-21 2014-02-26 Krohne Messtechnik GmbH Method for secure adjusting the parameters of a field device

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10258075B4 (en) * 2002-12-11 2012-11-29 Endress + Hauser Gmbh + Co. Kg Device for signal transmission between a field device and an external unit
US8145180B2 (en) 2004-05-21 2012-03-27 Rosemount Inc. Power generation for process devices
US8160535B2 (en) 2004-06-28 2012-04-17 Rosemount Inc. RF adapter for field device
US7262693B2 (en) 2004-06-28 2007-08-28 Rosemount Inc. Process field device with radio frequency communication
DE102005001601B4 (en) * 2005-01-12 2011-07-28 Endress + Hauser GmbH + Co. KG, 79689 Field device with bus interface
US7391297B2 (en) 2005-03-12 2008-06-24 Lutron Electronics Co., Inc. Handheld programmer for lighting control system
US8452255B2 (en) 2005-06-27 2013-05-28 Rosemount Inc. Field device with dynamically adjustable power consumption radio frequency communication
US8000841B2 (en) 2005-12-30 2011-08-16 Rosemount Inc. Power management in a process transmitter
WO2009154748A2 (en) 2008-06-17 2009-12-23 Rosemount Inc. Rf adapter for field device with low voltage intrinsic safety clamping
US8847571B2 (en) 2008-06-17 2014-09-30 Rosemount Inc. RF adapter for field device with variable voltage drop
CN102084626B (en) 2008-06-17 2013-09-18 罗斯蒙德公司 RF adapter for field device with loop current bypass
US8929948B2 (en) 2008-06-17 2015-01-06 Rosemount Inc. Wireless communication adapter for field devices
US8694060B2 (en) 2008-06-17 2014-04-08 Rosemount Inc. Form factor and electromagnetic interference protection for process device wireless adapters
US8626087B2 (en) 2009-06-16 2014-01-07 Rosemount Inc. Wire harness for field devices used in a hazardous locations
US9674976B2 (en) 2009-06-16 2017-06-06 Rosemount Inc. Wireless process communication adapter with improved encapsulation
US10761524B2 (en) 2010-08-12 2020-09-01 Rosemount Inc. Wireless adapter with process diagnostics
US9310794B2 (en) 2011-10-27 2016-04-12 Rosemount Inc. Power supply for industrial process field device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993004452A1 (en) * 1991-08-14 1993-03-04 Rosemount Inc. Hydrostatic interface unit to detect digital communication signals
DE4232922A1 (en) * 1992-09-28 1994-03-31 Mannesmann Ag Data transmission network for process system - uses bidirectional bus coupler between each field device and data bus leading to operating device
DE4343540A1 (en) * 1993-12-14 1995-07-27 Mannesmann Ag Arrangement for the isolated transmission of direct and alternating current signals

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993004452A1 (en) * 1991-08-14 1993-03-04 Rosemount Inc. Hydrostatic interface unit to detect digital communication signals
DE4232922A1 (en) * 1992-09-28 1994-03-31 Mannesmann Ag Data transmission network for process system - uses bidirectional bus coupler between each field device and data bus leading to operating device
DE4343540A1 (en) * 1993-12-14 1995-07-27 Mannesmann Ag Arrangement for the isolated transmission of direct and alternating current signals

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ORRISON IV G A: "TAKING FULL ADVANTAGE OF SMART TRANSMITTER TECHNOLOGY NOW", CONTROL ENGINEERING INTERNATIONAL, vol. 42, no. 1, 1 January 1995 (1995-01-01), pages 59 - 61, XP000500027 *
SCHOLZ W ET AL: "INTERKAMA '92: INTELLIGENTE MESSUMFORMER FUER DIE PROZESSMESSTECHNIK INTERKAMA '92: INTELLIGENT TRANSMITTERS FOR PROCESS MEASUREMENT", TECHNISCHES MESSEN TM 1982 - 1988 INCOMPLETE, vol. 60, no. 4, 1 April 1993 (1993-04-01), MÜNCHEN,DE, pages 157 - 161, XP000359605 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103471637A (en) * 2004-03-29 2013-12-25 罗斯蒙德公司 Two wire transmitter with isolated CAN output
CN103471637B (en) * 2004-03-29 2016-08-10 罗斯蒙特公司 There is the two wire transmitter of isolated can output
WO2008052877A1 (en) 2006-10-31 2008-05-08 Endress+Hauser Gmbh + Co. Kg System for determining and/or monitoring at least one process quantity
CN101535770B (en) * 2006-10-31 2012-08-29 恩德莱斯和豪瑟尔两合公司 System for determining and/or monitoring at least one process quantity
US8354941B2 (en) 2006-10-31 2013-01-15 Endress + Hasuer Gmbh + Co. Kg Apparatus for determining and/or monitoring at least one process variable
WO2008061935A1 (en) * 2006-11-22 2008-05-29 Endress+Hauser Wetzer Gmbh+Co. Kg Signal isolation unit for a dual-conductor process control loop
EP2701018A1 (en) * 2012-08-21 2014-02-26 Krohne Messtechnik GmbH Method for secure adjusting the parameters of a field device
CN103631175A (en) * 2012-08-21 2014-03-12 克洛纳测量技术有限公司 Method for configuring a field device and corresponding field device and system for parameterization

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