EP1932039A1

EP1932039A1 - Optical communication bus network for avionic equipment

Info

Publication number: EP1932039A1
Application number: EP06808265A
Authority: EP
Inventors: Gilles Tournier
Original assignee: Airbus Operations SAS
Current assignee: Airbus Operations SAS
Priority date: 2005-08-31
Filing date: 2006-08-31
Publication date: 2008-06-18
Also published as: US8636427B2; CA2620025A1; CN101375193A; JP2009505899A; WO2007026102B1; CN101375193B; BRPI0615037A2; WO2007026102A1; FR2890275B1; RU2008111743A; FR2890275A1; RU2428726C2; US20120141066A1

Abstract

The invention relates to an avionic system for an aircraft comprising at least two pieces of equipment (10a, 10b) which can exchange information by means of at least one electrical bus for simultaneous bidirectional communication, in which the information can be exchanged between pieces of equipment (10a, 10b) via an optical bus (20) that can be connected to the electrical interfaces (11a, 11b) of said equipment. The optical bus (20) of the avionic system comprises at least one optical cable (21) consisting of at least one optical fibre (22) and, at each end, a connector (30) comprising means (41, 42, 45, 46) for converting electrical signals into optical signals and means for converting optical signals into electrical signals. The optical bus (20) is connected to the electrical outlets of existing equipment.

Description

OPTICAL COMMUNICATION BUS NETWORK FOR AVIONICS EQUIPMENT

The present invention relates to means for connecting, by means of an optical communication bus network, avionics equipment on board an aircraft when these devices have been designed for communications by an electric bus network, and this without the need for it is necessary to modify said avionics equipment.

Current civil aircraft rely heavily on digital technologies. Various equipment comprising an electronic communication interface, such as computers or other equipment equipped with microprocessors, microcontrollers or digital interfaces, provide the command, control and monitoring functions on board the aircraft and exchange information. information on digital buses.

The most used buses are electric buses using cables with a conductive metal core, usually based on copper or aluminum. The digital data is then transmitted in the form of voltage variations. The technology of the electric buses, in particular the serial buses or the coded information are issued successively on the same physical medium, is justified in particular by the reliability of the connection means which are, on board aircraft, subjected to severe operating environments. However, these electric buses have the defect of being relatively heavy and of being sensitive to electromagnetic disturbances.

The need, especially for operational reasons of interchangeability, of a high stability of the definition of the equipment implemented on board the aircraft, in particular at the level of their physical and functional interfaces, leads the aircraft manufacturers to standardize the mechanical and electrical interfaces of this equipment. For example, the aeronautical world is familiar with the ARINC 429 standard, which defines in detail the interfaces and communication protocols between the equipment on board aircraft using mono directional buses that meet this standard.

More recently, the simplification of physical buses has been made possible by the increase of the speeds that these buses are able today to support with the conditions of reliability necessary for the aeronautical applications. Thus several relatively modest single-directional buses used in systems compliant with the ARINC 429 standard can be replaced by a high-speed bidirectional bus, of hundred megabytes per second, for example. These high-speed bidirectional buses are associated with new standards and, of course, new communication interfaces for avionics equipment.

These new interfaces are still currently associated with electric communication buses for the reasons of operational reliability already mentioned.

In Figure 1 is presented an architecture for a set of embedded electronic equipment connected by a high-speed electric bus.

In this example, computers 1a, 1b, 1c are connected, by electric communication buses 4a, 4b, 4c respectively, to a switch 2 which is an equipment capable of passing the signals from one bus to another in function of the addressing signals that arrive on the bus itself. Other devices 3a, 3b, for example sensors or actuators, are connected directly to the computers respectively 1a, 1b to the electrical communication bus means 5a, 5b respectively.

Simultaneous bidirectional electrical communication buses, called FuII Duplex, generally consist of two pairs of electrical conductors, or quadraxial cable, each pair being dedicated to a sense of communication. In general, each pair is twisted, and the cable thus formed has a shield for protecting the cables from electromagnetic attack from outside and protecting the external environment from electromagnetic radiation that could be emitted by the cable. These cables often have linear masses of the order of 40 to 50 g / m. The cable is equipped at each of its ends with connectors having four electrical contacts, male or female as required, with a recovery of the shield on the metal structure of the connector. The ARINC 600 standard (see supplement 14 annex 20 of the provisional edition of July 15, 2003) describes the electrical and mechanical characteristics of such a quadraxial type connector. On these connectors with 4 electrical contacts, the two contacts dedicated to the transmission are generally marked Tx + and Tx- and the two contacts dedicated to the reception are generally marked Rx + and Rx-. The signs + and - remind that the bus is polarized and that this polarity must be respected when mounting the connectors on the electrical cable of the bus.

It is also possible to convert the information to be transmitted into optical signals that can propagate in optical fibers. Optical communication buses, which have advantages in terms of line density, information rate and insensitivity to electromagnetic radiation, are not yet widely used in the field of civil transport aircraft because of the connection problems of optical links and because of the current equipment technology which is today mainly adapted to operate with electric communication buses.

The present invention proposes to make it possible for aircraft whose equipment is designed to operate with electrical communication buses to have the possibility of communicating via optical communication buses and therefore to benefit from this technology, particularly in terms of mass and reliability. insensitivity to electromagnetic disturbances, two problems that are particularly critical for aircraft, without calling into question the existing definition of the equipment connected to these buses and which responds, and must still respond for several years, to standards that correspond to electric communication buses.

For this purpose in an aircraft avionics system according to the invention comprising two or more equipments designed to exchange information by means of one or more electric buses of simultaneous bidirectional communication at least one of the electric buses is replaced by at least one optical bus whose end connectors are capable of being connected to electrical interfaces of said equipment. In a preferred embodiment of the avionic system, the optical bus comprises at least one optical cable with at least one optical fiber and at each end a connector incorporating means for converting the electrical signals into optical signals and means for converting the optical signals. in electrical signals.

The connector of the optical cable has at its end intended to be connected to a device an electrical and mechanical interface identical to those of electric buses of the quadraxial type having two electrical transmission contacts and two electrical contacts for receiving electrical signals.

In one embodiment of the invention, the electro-optical means for converting the signals incorporated in the connector are powered by at least one conductive wire that can be connected to a source of energy outside the connector. The electrical grounding of the electro-optical conversion means can be achieved by a second conductive wire connected to the ground of the aircraft or preferably by the structure of the housing of the connector.

In another embodiment, the electro-optical means for converting the signals incorporated in the connector are powered by a voltage applied to one of the electrical contacts, either of transmission or of reception, of the connector. Preferably in this case, the avionics equipment supplies at the bus plug of the equipment, on the contact selected, either transmission or reception, the voltage required to supply the electro-optical means, the other contacts being protected against the effects of this voltage in the case where an electric communication bus is connected and lead to applying said supply voltage to the contact facing the contact serving for supply. By these precautions the avionics system can use either an electric communication bus or an optical communication bus on a link between two devices.

The invention also relates to a simultaneous bidirectional bus for the communication of data in digital form between avionics equipment of an aircraft comprising an optical cable incorporating at least one optical fiber with at the first end of said optical cable a first connector comprising means maintaining the optical cable and positioning the optical fiber, electro-optical means for converting electrical signals in optical signals of wavelength λ 1, electro-optical means of

converting optical signals of wavelength λ 2 into electrical signals, electrical contacts geometrically and electrically in accordance with those of a quadraxial type electric bus and with at the second end of said optical cable a second connector comprising means for maintaining the optical cables similar in their functions to those of the first connector, electro-optical means for converting electrical signals into optical signals of wavelength λ 2, electro-optical means for converting signals

optical wavelength λ 1 electrical signals, and electrical contacts geometrically and electrically consistent with those of a quadraxial type electric bus but may be different from those of the first connector.

For the implementation of the embodiment in which the electro-optical conversion means of the connector are powered by one or more contacts of the electrical connector of the optical bus, the invention also relates to avionics equipment comprising at least one plug for two-directional digital bidirectional communication electric bus of quadraxial type such that a supply voltage for the electro-optical conversion means is superimposed on the digital signal on at least one of the two electrical contacts of the socket dedicated to the transmission of signals on the electric communication bus and further comprising means for a digital signal, terminating on the electrical contacts dedicated to the reception, to be correctly received by the equipment whether or not this signal is superimposed on a voltage of the same characteristics as the supply voltage of the electro-optical conversion means.

Similarly, the invention relates to an avionics equipment comprising at least one quadraxial type bidirectional digital communication electric bus socket such that a supply voltage for the electro-optical conversion means is generated on at least one of the two electrical contacts of the receptacle dedicated to receiving signals and comprising means for a digital signal, emitted on the electrical contacts of the taken dedicated to the transmission, either correctly transmitted by the equipment that these contacts or one of these electrical transmission contacts are or not subject to a voltage of the same characteristics as the supply voltage of the electro-optical conversion means.

A description of preferred embodiments of the invention is described with reference to the figures:

- Figure 1: state of the art, already mentioned, an electric communication bus network;

FIG. 2: exemplary communication bus network architecture according to the invention;

- Figure 3: Installation details of avionics equipment and its electrical connection means; detail (a) is an end view of the connector, electrical contacts side;

FIG. 4: details of an electrical connector (partial section) for an optical bus according to the invention;

- figure 5: optical bus (partial cuts) with electrical connection of quadraxial type

The avionic system according to the invention comprises a set of equipment, at least two, 10a, 10b, on board an aircraft and which exchange information by a communication bus network using at least one optical digital bus 20.

These devices 10a, 10b may be of any kind but are able to transmit and / or receive digital information, for example computers performing more or less complex operations relating for example to the piloting, the conduct of the mission or to the monitoring the aircraft and its systems, sensors or sensor measurement concentrators, actuators, communication bus network-specific equipment such as electronic switches or electronic routers.

All the equipment 10a, 10b considered have at least one bus connection interface 11a, 11b having at least one socket electric quadaxial type, to be connected to at least one bidirectional electric communication bus for the exchange of information with one or more other equipment.

In the present avionic system architecture, despite the interfaces 11a, 11b which are defined so that these devices 10a, 10b are connected by electrical communication buses, at least one link for exchanging information between the equipment 10a, 10b , is carried out using an optical communication bus 20 comprising an optical cable 21 provided at its ends with connectors 30a, 30b, whose terminations comprise electrical connection sockets compatible with the quadraxial cable electrical sockets of the equipment 10a, 10b .

The electrical connection plug of the connector 30 comprises two contacts 32a and 32b dedicated to the transmission of information from the avionics equipment 10 and two contacts 33a, 33b dedicated to the reception of information by the avionics equipment . In order to ensure the conversion of the electrical signals into optical signals for the pair of contacts 32a, 32b intended to be connected to the emitter contacts of the socket of the computer 10 and the conversion of the optical signals into electrical signals for the pair of contacts 33a, 33b intended to be connected to the receiving contacts of the socket of the computer 10, each connector 30 mounted at one end of the optical communication bus 20 comprises electro-optical components configured to perform these conversions, either electrical optical 45 or optical electrical 46 Such electro-optical components are already known for the realization of data transmission systems by means of optical fibers. Installed in the electronic equipment, the optical fiber connection is done in this case on the equipment by means of an optical connector. There are also electro-optical components that integrate the two functions of conversion, electrical to optical and optical to electrical, which is useful in applications with little space and when the two directions of communication are supported by the same optical fiber.

The connector 30 functionally comprises three zones: a first end zone intended to cooperate with the electronic equipment by means of an electrical coupling; geometrically and electrically identical to the quadraxial bus type connectors and in accordance with the definition required for the avionics equipment 10 considered; an intermediate zone 40 comprising the electro-optical means for converting the electrical signals from the equipment 10 into optical signals 45 for transmission on the optical communication bus 20 and conversion of the optical signals into electrical signals 46 for reception from the optical communication bus 20 to the equipment 10, as well as electronic circuits respectively 41 and 42 associated with the electro-optical components 45 and 46 to ensure its operation; a second end zone 50 at the opposite of the first zone 31 on the connector 30 adapted to be connected to the optical cable 21, ie to ensure the mechanical connection between the connector 30 and the optical cable 21 and to guarantee the positioning of the optical fiber or fibers 22 which transmit the optical signal.

The first end zone 31 of the connector 30 must comply with the definition of the electrical interfaces expected by the avionics equipment in question and guarantee, in particular by its geometry, the mounting on the receptacle 13 generally fixed at the rear of the cradle , the rack, 12 which must receive the avionics equipment 10, or the mounting directly on the interface 11 of the avionics equipment if it has provided such direct mounting.

The intermediate zone 40 of the connector 10 contains the electro-optical portion of the connector 30. Preferably, the most miniaturized electro-optical components possible compatible with the size of the existing quadraxial electrical cable connector housings are used, but, if the constraints to the integration of the electronic and electro-optical components require it, it is necessary to change the geometry of this zone 40 compared to that of a conventional quadraxial type connector, for example by lengthening it, making sure that it does not lead the impossibility of mounting the connector 30 on the receptacle 13 of the rear part of the rack 12 support of the equipment 10 or on the equipment itself. The electro-optical converter comprises:

at least one electronic circuit 41, 42;

- Electrical connections 43, 44 of the electrical contacts 32a, 32b, 33a, 33b of the connector to said at least one electronic circuit 41, 42;

at least one conversion component 45 of an electrical signal into an optical signal (for example a light-emitting diode, a laser diode, etc.) electrically connected to the emission components 41 of the at least one electronic circuit 41, 42;

at least one conversion component 46 of an optical signal into an electrical signal (for example a phototransistor ...) electrically connected to the reception components 42 of the at least one electronic circuit 41, 42.

In a particular embodiment of the invention, means for processing the electrical signals, for example amplifiers or signal shaping circuits, are mounted in the connector 30, for example to improve the quality of the transmitted signal. These means may be separate from the electronic circuit 41, 42 or incorporated therein.

Since the optical communication bus 20 must be bidirectional and simultaneous, the transmit and receive signals are advantageously transmitted on the same optical fiber (s) 22 of the optical cable 21, while they pass on pairs of distinct electrical conductors in the case a conventional quadraxial electric bus. In order to separate the optical signals in emission from the optical signals in reception, these will be transmitted preferably by using optical signals of different wavelengths, λ 1

and λ 2, for each of the communication directions, which is obtained by means of transmitter components 45 and receivers 46 optical signals adapted to the selected wavelengths and or by means of filters, not shown in the figures, selective lengths selected waveforms and associated with the transmitter components 45 and 46 receivers. For example, with the electro-optical components and optical fibers known in the field of optical communications, the signals are transmitted with wavelengths centered on 1310 nanometers in one direction along the optical fiber and with wavelengths centered on 850 nanometers in the other direction to obtain a good separation of the transmitted signals in each direction.

Note that if λ 1 is the wavelength corresponding to the signals transmitted at one end, for example that corresponding to the connector 30a, of the optical bus 20, that is to say the length at which the optical component 45a is adapted to transmit the optical signal injected into the optical fiber 22, it is at this same wavelength λ 1 that the optical component 46b receiving the optical signal at the other end of the optical bus 20, corresponding to the connector 30b in this connection, must be adapted. example. At this same other end of the optical bus the optical component 45b associated with the connector 30b must be adapted to transmit the optical signal at the wavelength λ 2 which is also the wavelength at which the optical reception component 46a associated with the connector 30a at the first end of the optical bus 20 must be adapted. Thus for each optical bus 20 of the network, that is to say an element comprising an optical cable 21 between 2 connectors 30a, 30b having ends with electrical contacts of quadraxial type, the connectors 30a and 30b located at each end of the optical bus 20 are different in that the transmission and reception wavelengths are reversed between the two connectors. The characteristics of the electro-optical components 45 and 46 providing the transmission and reception functions are therefore adapted to take account of this inversion. If we do not consider the geometrical aspect of the ends 31 having the electrical connections, which however must respect the conditions of polarity of the quadraxial plug, on the connectors 30a, 30b mounted at both ends of the optical communication bus 20, which may be identical or different depending on the destination of the bus, the connectors 30a and 30b must be complementary because of the different optical characteristics for the two directions of communication of the transmitted signals.

In practice, to meet the need to make optical communication buses 20 equipped at each of their two ends indifferently with a male connector or a female connector, it is necessary at least four connector models for replacing the quadraxial type electrical communication buses with optical communication buses according to the invention, namely:

- Model MA: male connector transmitting the signals at the wavelength λ 1 and receiving the signals at the wavelength λ 2;

- Model FA: female connector emitting the signals at the wavelength λ 1 and receiving the signals at the wavelength λ 2;

- Model MB: male connector emitting the signals at the wavelength λ 2 and receiving the signals at the wavelength λ 1;

- Model FB: female connector emitting the signals at the wavelength λ 2 and receiving the signals at the wavelength λ 1;

The optical communication buses 20 according to the invention will thus be made with combinations of connectors 30a, 30b at their male-male or male-female or female-female ends, while respecting a combination of xA-B type connector models in which x and y will be M or F depending on the needs of the communication bus network for which the buses are intended.

To limit the risk of mounting identical connectors 30a and 30b in their optical operation at the ends of the same optical communication bus 20, for safety and quality control purposes, the connectors 30a, 30b of the two types with regard to their optical operation are differentiated for example by means of different shapes of a portion of the connector 30 whose shape is not likely to interfere with the mounting of the connectors on the receptacles 13 of destination and or color code and or markings 47a, 47bsur the body of the connectors 30a, 30b. Despite this dissymmetry in the optical operation internal to the optical communication bus 20, the bus 20 has no functional meaning and it also works whether it is connected in one direction or the other between the two devices. 10a, 10b between which it ensures the transmission of data, if the electrical interfaces are compatible and if no mechanical means limit the mounting direction of the optical communication bus 20. Another aspect of the optical communication bus 20 is related to the power supply of the components of the electronics incorporated in the connectors 30. The components currently used for converting electrical signals into optical signals or vice versa generally require a power supply. DC low voltage (a few volts). It is therefore necessary to bring such a power supply to the connector 20 and the electronic circuits incorporated in the intermediate zone 40. This power supply is for example made by means of a single power supply wire 34 which is connected to a source of power. voltage, not shown, adapted to the need of the electronics incorporated in the connector 20. For example the power wire 34 is equipped at its free end with an electrical contact 35 adapted to be inserted into a housing of the receptacle 13 or an equivalent receptacle, said housing corresponding to an electrical contact point or the desired voltage is available. In general, avionics system designers provide on the receptacles of connectors and electrical contacts free locations in reserve on which contacts can be wired to bring the desired voltage from the electrical generations of the aircraft. The electrical mass of the housing 36 of the connector 30 being generally, once the connector 30 connected, connected to the electrical ground of the aircraft then ensures the return of current. If the current return by the ground of the limb of the connector 30 is not desired or is not possible, a second wire 37 is provided whose opposite end to the connector 30 is connected to the electrical ground of the aircraft. If the voltage necessary for the operation of the electronics incorporated in the connector 30 is one of the voltages necessary for the operation of the electronic equipment 10 concerned, this voltage is generally available on a contact of the receptacle 13 of the bottom of the rack 12.

In a particular embodiment of the invention, the avionics equipment 10a, 10b are modified so that a voltage is superimposed on the signal on at least one electrical contact of the connector of the avionics equipment 10 to which to connect the end connector 30 of the optical communication bus 20. Advantageously the supply voltage is applied between an electrical contact of the relevant connector of the avionics equipment 10 and the electrical mass of this connector, generally connected to the electrical ground of the equipment 10. It is also possible to apply the supply voltage between two of the electrical contacts of the relevant connector of the avionics equipment 10. Such a voltage , continuous or quasi-continuous with respect to the frequencies of the signals carrying the information transmitted on the communication bus, does not affect the quality of the digital signal to be transmitted and makes it possible to supply the electronic circuits 41, 42 incorporated in the connector 30 of optical communication bus end 20, directly by the internal power supply of the avionics equipment 10. This embodiment avoids additional electrical wiring at the receptacle 13 of the rack 10 of the equipment support 10 .

When the power supply of the connector 30 by the avionics equipment 10 is made only by one or both of the emission contacts 32a, 32b of the connector 30 or only by one or both of the receiving contacts 33a, 33b, this choice is a priori arbitrary, decoupling means between the signals and the power supplies are advantageously provided for the avionics equipment to operate indifferently with optical communication buses according to the invention and conventional quadraxial electrical communication buses that the buses optical communication replace. When the power supply voltage of the connector 30a is applied to an electrical contact, for example the transmission contact 32a if this choice is made, by the equipment 10a located at one end of the communication bus, this voltage ends, when a traditional quadraxial electrical communication bus connects the two devices 10a and 10b, on a different contact of the second equipment 10b, the receiving contact 33a in the choice chosen by way of example, which contact is associated with said decoupling means which are incorporated in the avionics equipment 10 modified to supply the internal electronics of the connectors 30 according to the invention. These decoupling means separate the signal and the supply voltage so that the operation of the avionics equipment 10 is not disturbed by the application on the electrical contact of the plug of said avionics equipment of the voltage coming from the avionics equipment connected to the other end of the electrical communication bus. Such means may for example be realized by means of capacitors that stop the quasi-continuous component of the supply voltage and let pass signals that are of high frequencies.

The second end zone 50 of the connector 30 serves to maintain the optical cable 21 at the end of the connector 30 by ensuring the alignment of the optical fiber 22 with the optical windows 51 for transmitting and receiving signals. optical electro-optical components 45, 46 of the intermediate zone. This assembly requires a very high precision and the quality of its implementation depends on the quality of the transmission of the signal that passes through the optical fiber. Among the criteria which have a significant impact on the quality of the transmission, and on the duration during which this quality will be maintained, are the absence of dust, grease or other elements which can reduce the transparency of the optical connection, the perpendicularity and the polishing the end of the optical fiber, centering the fiber with respect to the electro-optical components. The methods of mounting the end of an optical cable to obtain good transmission qualities are known, including the consideration of the mechanical strength of the connection and sealing of the mounting. The bus according to the invention enables these assembly operations to be carried out in specialized workshops where all the conditions to obtain the required quality can be guaranteed with means which are very difficult, if not impossible, to be used industrially to obtain the same quality. when the optical connection is made at the time of mounting the optical bus 20 in the aircraft.

Thus, with an avionic architecture using the communication buses 20 according to the invention, all connections and connection / disconnection operations are performed on electrical contacts without any particular fragility. The aircraft operator does not need at any time to take into consideration that an optical bus is implemented and in particular he does not need to provide the particular conditions for maintenance operations that the use of optical connectors imposes. Aircraft maintenance crews therefore do not need to receive any special training or qualifications other than those acquired for the purpose of maintenance of existing electric buses. In addition, since the avionics equipment 10 is fully compatible with an electrical communication bus network and with an optical communication bus network according to the invention, there is no risk of error on the model of communication. the equipment and an airline that uses aircraft equipped with both types of bus does not need to manage two families of equipment depending on the type of communication bus installed on each aircraft.

When the embodiment of supplying the internal electronics of the connectors 30 by a contact of the connector by means of modified electronic equipment is implemented, it is possible to replace, for example during a maintenance operation, an electric communication bus via an optical communication bus according to the invention, or conversely, without it being necessary to intervene on the wiring of the receptacle 13 of the avionics equipment 10.

Claims

1 - aircraft avionics system comprising at least two devices (10a, 10b) capable of exchanging information by means of at least one simultaneous bidirectional communication electric bus, characterized in that information is exchanged between the equipment (10a, 10b) using at least one optical bus (20) adapted to be connected to electrical interfaces (11a, 11b) of said equipment.

2 - avionics system according to claim 1 wherein the at least one optical bus (20) comprises:

at least one optical cable (21) comprising at least one optical fiber (22), and;

at each of its ends, a connector (30) incorporating means (41, 42, 45, 46) for converting electrical signals into optical signals and means for converting optical signals into electrical signals.

3 - avionics system according to claim 1 or claim 2 wherein the end (31) of the connector (30) intended to be connected to equipment is of the quadraxial type having two electrical contacts (32a, 32b) dedicated to the transmission of electrical signals and two electrical contacts (33a, 33b) dedicated to the reception of electrical signals.

4 - avionics system according to claim 2 or claim 3 wherein the means (41, 42, 45, 46) incorporated in the connectors (30) for converting electrical signals into optical signals or optical signals into electrical signals comprises components electronics (41, 42) fed by at least one conductive wire (34) adapted to be connected to a source of energy external to the connector (30). 5 - avionics system according to claim 2 or claim 3 wherein the means (41, 42, 45, 46) incorporated in the connectors (30) for converting electrical signals into optical signals or optical signals into electrical signals comprise components electronics (41, 42) powered by at least one of the electrical contacts (32a, 32b, 33a, 33b) of the connector (30).

6 - avionics system according to claim 5 wherein the at least one electrical contact by which are supplied the means (41, 42, 45, 46) incorporated in the connector (30) for converting the signals is one of the electrical contacts (32a, 32b) dedicated to the transmission of information.

7 - avionics system according to claim 5 wherein the at least one electrical contact by which are supplied the means (41, 42, 45, 46) incorporated in the connector (30) for converting the signals is one of the electrical contacts (33a, 33b) dedicated to receiving the information.

8 - avionics system according to claim 6 wherein at least one of the equipment (10) comprises a power source capable of supplying energy to the means (41, 42, 45, 46) for converting the signals incorporated in the connector (30), which power source is connected to at least one electrical signal-emitting contact of the socket of the at least one equipment to which a connector (30) of the optical bus (20) is to be connected.

9 - avionics system according to claim 7 wherein at least one of the equipment (10) comprises a power source capable of supplying energy to the means (41, 42, 45, 46) for converting the signals incorporated in the connector (30), which power source is connected to at least one electrical signal receiving contact of the socket of the at least one equipment to which a connector (30) of the optical bus (20) is to be connected. 10 - avionics system according to one of claims 5 to 9 wherein at least one of the equipment (10a) comprises means for making the electrical contacts of the socket of said equipment functionally insensitive to the presence of an electrical voltage generated by the other equipment (10b), allowing it to use either an electrical communication bus or an optical communication bus (20) on at least one socket of the electrical interface (11a) connecting the communication buses.

Simultaneous bidirectional bus (20) for digital data communication between avionics equipment of an aircraft comprising:

an optical cable (21) incorporating at least one optical fiber (22);

at a first end of the optical cable (21) a connector (30a) comprising: c means for holding the optical cable (21) to make the optical cable (21) integral with the connector (30) ensuring the desired positioning of the at least one optical fiber (22); c electro-optical means (41a, 45a) for converting electrical signals into optical signals of wavelength λ 1; c electro-optical means (42a, 46a) for converting optical signals of wavelength λ 2 into electrical signals; c electrical contacts (32a, 32b, 33a, 33b) geometrically and electrically in accordance with those for a quadraxial type electric bus;

- At the second end of the optical cable (21) a connector (30) comprising: c means for holding the optical cable (21) to make the optical cable (21) integral with the connector (30) ensuring the desired positioning of the at least one optical fiber (22); c electro-optical means (41b, 45b) for converting electrical signals into optical signals of wavelength λ 2; c electro-optical means (42b, 46b) for converting optical signals of wavelength λ 1 into electrical signals; c electrical contacts (32a, 32b, 33a, 33b) geometrically and electrically in accordance with those for a quadraxial type electric bus;

12 - avionics equipment (10) comprising at least one socket for bidirectional simultaneous digital communication bus of quadraxial type characterized in that a supply voltage for external electro-optical conversion means to the equipment is superimposed to the digital signal on at least one of the two electrical contacts of the socket dedicated to the transmission of signals on the electrical communication bus and in that it comprises means for a digital signal, terminating on the electrical contacts dedicated to the reception of the socket, either received correctly by the equipment whether or not this signal is superimposed on a voltage of the same characteristics as the supply voltage of the electro-optical conversion means.

13 - Avionics equipment (10) comprising at least one quadraxial type bidirectional digital communication electrical bus socket, characterized in that a supply voltage for electro-optical conversion means external to the equipment is generated on at least one of the two electrical contacts of the socket dedicated to receiving signals from the electrical communication bus and in that it comprises means for a digital signal, transmitted on the electrical contacts of the socket dedicated to the transmission , either correctly transmitted by the equipment whether or not these contacts or one of these electrical transmission contacts are subjected to a voltage of the same characteristics as the supply voltage of the electro-optical conversion means.