Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/40—Bus networks
  • H04L12/40006—Architecture of a communication node
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/46—Interconnection of networks
  • H04L12/4604—LAN interconnection over a backbone network, e.g. Internet, Frame Relay
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/40—Bus networks
  • H04L2012/40267—Bus for use in transportation systems
  • H04L2012/4028—Bus for use in transportation systems the transportation system being an aircraft

Definitions

• the present invention relates to a device for connecting a plurality of electronic equipment to an ARINC 629 type bus.
• the electronic equipment Ei is connected to a main cable 1, or aircraft cable, by means of a double down cable 13, called “stub", which is connected to the main cable 1 thanks to a simultaneously bidirectional coupler 5, of the non-intrusive inductive type, this coupler ensuring the conversion between the voltage doublets circulating in the down cable and the current doublets circulating in the main cable.
• This topology allows distances between devices of around 100 meters, and authorizes the connection of up to 120 devices.
• the main cable 1 constituting the bus is used in multi-transmitter multiplex mode, so that the information circulating on the bus is transmitted by one device at a time, then broadcast to all the other devices connected to the bus.
• the information sent is monitored in real time by the sending equipment via the information returned by its connection to the bus.
• the down cable 13 is constituted by a double twisted pair, namely a pair for the transmission channel 4 and a pair for the reception channel 3, thus allowing simultaneous transmission and reception on the transmission cable. descent, and therefore real-time monitoring of emissions. It is controlled in the El equipment by a SIM 629 serial interface module ensuring the physical interface between the down cable and the TC 629 function of the equipment, called “Terminal Controller" which controls the transmission and reception of messages. of the equipment user subsystem.
• the area where collisions occur that is to say, the area in which signals from different equipment can be present simultaneously corresponds to the entire main cable.
• the main cable must have a low attenuation, a controlled impedance with a low tolerance (2%) over its entire length, as well as a very precise adaptation (to 4%), knowing that all the passive elements of the physical layer must not induce false physical information in the form of parasitic reflections which must be then processed by the equipment.
• the SIM module of each device must be capable of monitoring and adapting to varying levels of signals on reception, with the need to distinguish the correct physical information during transmission, therefore of high level, and the physical information transmitted remotely, therefore attenuated levels, compared to information resulting from collision cases.
• the elements of the physical layer namely the main cable, the SIM module of each device, as well as the stub and the connection coupler of each device, present very high costs due to the very narrow tolerance required.
• the physical characteristics of the passive components and the need to verify that the signals received fall within the templates of complex shapes, these templates being different depending on whether it is a control reception of a local broadcast, or reception of a remote program.
• the collision detection at the charge of the SIM module is carried out in a complex manner by a very precise analysis of the amplitude of the signal received at specific times, and of the width of the pulses and of the intervals between the pulses.
• the present invention aims to eliminate these drawbacks, starting from the observation that the electronic equipment is not distributed uniformly along the airplane bus, but that they are grouped together in well-defined zones, most of the equipment being arranged in the avionics bay under the cockpit. To this end, it offers a device for connecting a plurality of electronic equipment making it possible to establish communications between them and with an external bus of the ARINC 629 type.
• this device is characterized in that it comprises:
• the equipment is connected to a device according to the invention thanks to a simplified SIM module, as well as to a descent cable or stub.
• the attenuation of the signals in transmission and in reception is constant inside the device, and not fluctuating as a function of the relative position of the equipment on the bus. All the equipment connected to the device therefore sees only one signal level whatever the position of the transmitting equipment along the local bus.
• connection channel of each of the equipment advantageously comprises logic means for detecting a transmission carried out by the equipment, delivering a detection signal which is sent to the other connection channels of the device according to the invention .
• Figures 1 and 2 illustrate the mode of connection of a device respectively to a bus
• FIG. 3 represents several devices according to the invention interconnected in series
• FIG. 4 represents the internal architecture of the connection device
• Figure 5 shows in detail a connection channel of the connection device
• Figure 6 shows in more detail an element for connecting the external bus to the local bus of the connection device
• Figures 7 and 8 illustrate an algorithm executed by one of the functions of the connection device
• FIG. 9 schematically represents a serial interface module SIM of an equipment connected to the connection device
• FIGS 10 and 11 illustrate two alternative embodiments of the connection device.
• FIG. 2 represents the mode of connection of an equipment Ei to the connection device 10 according to the invention.
• the device 10 comprises a plurality of connectors for down cables 13 with double twisted pair 3, 4, of the type shown in FIG. 1, so as to be able to connect to a plurality of Ei devices, and a channel for entry into transmission 6 and reception 7 by external bus
• Each piece of equipment El comprises, as in FIG. 1, a user subsystem which transmits and receives messages via a control unit or Terminal
• Controller TC629 and a SIM interface module with a simplified structure compared to that required by the ARINC 629 standard.
• FIG. 3 represents three connection devices 10, 10 ′, 10 "connected in series by two sections of external bus 14 constituted for example by a double twisted pair or even by an optical fiber.
• Each device 1 to 3 comprises a multiplicity of points connection of down cable or stub 13 allowing the connection of electronic equipment which must communicate with each other.
• connection device 10 is in the form of a closed box 11 made of a material which protects the internal circuits against electromagnetic radiation and lightning.
• the wall of the housing 11 serves as a mechanical support for the connectors of the equipment and external buses.
• the shape and dimensions of these connectors are chosen so as to reduce the size and weight of the box as much as possible and ensure the electrical continuity of the peripheral shielding of the down cables with the equipment.
• each connector 16, 17 is connected to a connection channel 18, 18 'electrically and physically separated as much as possible from the others, at least one connection channel 18' being connected to a connection connector 17 to an external bus 14.
• the electrical supply of the device is not ensured by a general supply, ma s in common mode by each of the devices, via their respective SIM modules .
• connection device may also be made for the connection device to have a modular structure with N independent channels, so as to further increase the separation between the channels.
• connection channels 18, 18 ′ are interconnected by a local bus 20, constituted for example by a double serial line of RS 485 type, of short length, for example less than 10 cm, so as to overcome problems due propagation time and attenuation of line signals.
• the opposite ends of the two series lines are respectively connected to each other by two respective adaptation resistors 19, so as to suppress signal reflections on the ends of the lines.
• connection device 10 can then comprise up to 32 channels 18, 18 '.
• connection channel 18, 18 includes:
• a transmitter / receiver stage 21, 21 ′ of RS 485 type comprising a transmitter powered by the equipment Ei and a receiver, both of which come to connect directly to the two lines of the local bus 20,
• a logic stage 22, 22 ′ grouping together the logic functions of the channel which is connected to the transmitter and to the receiver of the transmitter / receiver stage 21, 21 ′,
• a galvanic isolation stage 24 ensuring electrical isolation between the equipment Ei and the analog stage 23.
• the logic stage 22 of each connection channel 18 of an equipment Ei emits a validation signal Vei qu which is applied to the transmitter of the transmitter / receiver stage 21 to authorize or not a transmission on the local bus 20.
• the resources of the channel 18 'connected to the external bus 14 is supplied either by one of the pieces of equipment Ei, or by the external bus 14 via an OR gate 25 produced for example using a set of ORing diodes, at the input of which all the supply voltages Aei, Ae supplied by all the channels (18, 18 ') are applied.
• the galvanic isolation stage 24 is constituted by two transformers with transformation ratio equal to 1, one 28 being connected to the transmission channel TSA, TSB of the equipment Ei, and the other 29 to the reception channel RSA, RSB, the two transmission lines TSA and TSB being connected together by a resistor 27.
• the midpoints of the windings of the transformers 28, 29 connected to the connector 16, are connected to a power supply unit 26 which extracts a DC voltage from the signals circulating either on the differential transmission lines TSA, TSB, or on the differential reception lines RSA, RSB, and which distributes this DC voltage between a supply line Ai of channel 18, and a supply line Ae of the external channel 18 '.
• the signals TSA, TSB, RSA and RSB delivered by the SIM module of the equipment Ei must make it possible to supply the local channel 18, the external channel 18 ', as well as the external bus 14.
• the power supply unit 26 extracts the DC voltage from the signals transmitted by the external bus and delivers only a single DC voltage Ae.
• the analog stage 23 comprises in transmission a threshold detection device 30 ' which converts the differential signals TSA, TSB into a logic signal TXi, and a device for generating differential analog signals 31 which converts the logic signal RXi transmitted by the logic stage 22, 22 'in differential signals RSA, RSB.
• the logic stage 22 of the channels 18 connected to the equipment comprises:
• a serial link 32 which transmits the logic signal TXi coming from the threshold detection member 30 to the transmitter of the transmitter / receiver stage 21, a logic monitoring circuit 33 which receives all the signals TXi from all the channels of the connection device 10, as well as the signal RXe transmitted by the channel 18 'connected to the external bus, and the signal RXOi transmitted by the receiver of the transmitter / receiver stage 21, and delivers a validation signal, and
• a logic AND gate 34 which receives the RXOi signal and the validation signal from the logic circuit as an input
• the logic circuit 33 also delivers a signal Vei for validation of the transmission carried out by the transmitter of the transmitter / receiver stage 21, and a signal Vxi for validation of the transmission on the external bus.
• FIG. 6 represents the logic stage 22 'of the channel 18' connected to the external bus. This floor includes:
• serial link 35 which transmits the logic signal RXe coming from the threshold detection member 30 of the channel 18 'to the transmitter of the transmitter / receiver stage 21',
• a logic circuit for controlling the transmission 36 which receives the signal Rxe and all of the signals Vxi generated by the logic circuit 33, and delivers a signal for validating the signal TXe to be transmitted to the external bus, and
• a logic AND gate 37 which receives as input the signal TXeO transmitted by the receiver of the transmitter / receiver stage 21 ′, and the validation signal from the logic circuit 36, and which delivers the signal TXel corresponding to the valid TxeO signal, what is applied in input of the generation device 31 of the analog stage 23 of the channel 18 '.
• the logic circuit 36 makes it possible to prevent the signals transmitted by the external bus from being retransmitted thereto, so as to avoid any echo phenomenon.
• this circuit is limited to validating the transmission to the external bus only when, according to the signal RXe, the external bus is inactive, or according to the signals Vxi, the local bus is active.
• FIGS. 7 and 8 illustrate the algorithm executed by the monitoring logic circuit 33.
• This algorithm includes a first monitoring loop shown in FIG. 7 which relates to the signal TXi coming from the threshold detection member 30.
• the logic 33 examines the signal TXi to detect there an activity corresponding to a transmission triggered by the equipment Ei.
• the logic 33 validates the signal Vxi (step 41), and examines the signals TXi and RXe transmitted by the other channels 18, 18 '(step 42). If an activity is detected, indicating that the local bus 20 is in use, we are then in a collision situation and the logic 33 goes to step 44. Otherwise, monitoring of the activity of the bus 20 is continued for a certain observation time T and if during this time no activity on the bus 20 is detected, then the logic 33 restarts the execution of the loop in step 40 (step 43).
• step 44 we are in a collision situation on the local bus 20 and the logic 33 does not send the signal Vei, which blocks the transmitter of the transmitter / receiver stage 21, and does not validate the RXOi signal which corresponds to the TXi signal applied to local bus 20 and read back by the receiver of the transmitter / receiver stage 21 (step 45).
• This operation therefore prevents the signal sent by the equipment Ei from returning to the level of the module SIM of the equipment, which is interpreted as an erroneous transmission by the module the control unit TC629 which will stop the transmission in progress.
• step 46 the logic 33 waits for the stopping of this transmission by again monitoring the signal TXi, then unblocks by means of the signal Vei the transmitter of the transmitter receiver stage 21, and transmits the signal validation Vxi as well as a signal for validation of the signal RXOi (step 47), before returning to step 40.
• the second loop of the algorithm (FIG. 8) relates to the monitoring of the signal RXOi coming from the local bus 20.
• the logic 33 is put on hold for an activity on this signal, and when activity is detected, the logic 33 tests the activity at the level of the signal TXi (step 49). If activity is detected, logic 33 proceeds to step 40 of the first loop. Otherwise, the logic 33 tests the activity at the signals TXi and RXe of the other channels 18, 18 '(step 50).
• step 51 If an activity is detected, and if more than one channel is active (step 51), which corresponds to a case of collision between several other channels, the logic 33 then emits a signal in the direction of the AND gate 34 which invalidates the RXOi signal from local bus 20 (step 52), and returns to step 48.
• step 51 if in step 51, no collision is detected, we are then in reception from the local bus 20, and the logic 33 returns to step 48.
• step 50 If in step 50, all the other channels 18, 18 ′ are inactive, the signal RXOi received corresponds to a parasitic signal, and the logic 33 does not emit the signal Vei which makes it possible to block the transmitter of the stage transmitter / receiver 21 (step 53). If in this state, one continues to observe an activity on the signal RXOi, the parasitic signals come from another channel, otherwise they come from stage 21, and channel i is then considered to be faulty and is deactivated (step 55).
• FIG. 9 represents the SIM module to be integrated into each piece of equipment Ei connected to the connection device 10, this module being greatly simplified compared to the SIM629 module of the previous solution.
• the SIM module is connected on one side to the TC629 control unit and on the other to the down cable which comes to connect to the device 10. It includes:
• an input stage 61 which receives the logic signals 64 of Manchester type of the data to be transmitted and a transmission validation signal 63, transmitted by the control unit TC629,
• a second transformer 66 of galvanic isolation which receives the differential signals RSA and RSB, and transmits them to a differential reception stage 67,
• a reception logic circuit 68 which receives the output of the differential reception stage 67, and which converts the received signals into complementary signals of Manchester type, which are applied to the input 71 of the control unit TC629.
• the reception logic circuit 68 receives from the control unit TC 629 a signal 70 for validation of the reception, and is controlled by a local monitoring unit 69 which, in the case of a transmission, compares the signals transmitted with the signals received, by counting and comparing the number of transitions in each of these signals, and if a difference is detected, blocks the receiving logic circuit 68.
• the function of looping back the transmission to the transmitter is performed at the level of each channel of the device. It is therefore a local loopback.
• the loopback function would also implement the channel 18 'connected to the external bus, thus making it possible to carry out the control of each transmission on the external bus.
• connection device 10 comprising more channels than the 32 authorized by the RS 485 standard
• the two local buses 20, 20 ' are interconnected by means of a repeater device 38 comprising two transmitter / receiver stages 21', connected respectively to the local buses, and two logical stages 22 'connected respectively to the two transmitter / receiver stages 21 ', such as that used in the connection channel 18' of an external bus.
• the two logic stages 22 ′ are interconnected so that the TX output of one is applied to the RX input of the other.
• the transmitter / receiver stages 21 'and the logic stages 22' are each supplied as the stage 21 'of the channel 18', by means of a set of ORmg diodes 25 at the input of which are applied the DC voltages delivered by the channels 18, 18 'connected to the bus corresponding room.
• the signals RXA and RXB delivered by the two logic stages 22 ' are applied to the input of the logic stages 22' of the channels connected to the other bus.
• connection device 10 it is also possible to provide a redundant variant of the connection device 10, as shown in FIG. 11, so as to increase its availability.
• This figure shows in detail the structure of a channel 18 connected on one side to the equipment and on the other to two redundant local buses 20, 20 ′.
• Each channel 18 comprises two redundant analog stages 23 connected to a single galvanic isolation stage 24 (not shown in this figure).
• Each analog stage 23 is connected to a respective logic stage 22, each logic stage 22 being connected to a respective local bus 20, 20 ′, via a respective transmitter / receiver stage 21.
• the two logic stages 22 of each channel 18 carry out their own failure detection, and apply an error detection signal to the input of a consolidation logic circuit 59 which finalizes the choice made by the logic stages 22, this choice being monitored by loopback by the latter, and being applied directly and via an inverter 58 respectively to the two analog stages 23 so as to exclusively validate one of the respective reception channels.
• logic stages 22 also exchange the RX signals which are applied at the input of the monitoring logic circuit 33 of the other logic stage 22.
• connection channel 18 ′ to an external bus can be made in a similar manner to the channels 18. It is also possible to provide two redundant external buses.
• the connection device comprises two channels 18 'which are connected only to a single respective local bus and to a single respective external bus.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Small-Scale Networks (AREA)
• Selective Calling Equipment (AREA)

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• 1996
  • 1996-08-30 FR FR9610622A patent/FR2753028B1/fr not_active Expired - Lifetime
  • 1996-11-01 US US08/742,926 patent/US6289024B1/en not_active Expired - Lifetime
• 1997
  • 1997-08-22 WO PCT/FR1997/001519 patent/WO1998009404A1/fr not_active Application Discontinuation
  • 1997-08-22 EP EP97938943A patent/EP0860066A1/de not_active Withdrawn
  • 1997-08-22 CA CA002236139A patent/CA2236139A1/fr not_active Abandoned
  • 1997-08-29 CN CN97115285A patent/CN1176431A/zh active Pending

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