Method for coding communication conductors of a linear sensor in a system

Description

Technical field

[0001] The present invention relates to a method for coding communication conductors of a linear sensor belonging to a system. It also relates to a system for implementing said method. State of the prior art

[0002] To detect liquid leaks, over long lengths such as oil or water pipelines or over large areas such as industrial premises or computer rooms, it is known to install linear sensors connected together in series to form a detection line.

[0003] In such a detection line, each sensor comprises an elongated portion which includes over all or part of its length a means sensitive to the liquid(s) to be detected. The sensors also comprise in their elongated portion a communication bus, which are connected together to form an interrogation bus running the entire length of the detection line. The end of the detection line is connected to a central unit.

[0004] Such a detection line, in a version sensitive to hydrocarbons, is described in document EP3066443. Other detection modes are known, for example with sensitivity to conductive liquids such as water as described in documents FR2773613 and EP09306176.

[0005] Another example of prior art can be found in document GB2337675.

[0006] It remains desirable to improve this type of detectors and installations, particularly in terms of reliability, cost and performance, to enable them to cover larger, more varied areas, and to be more flexible in their installation, maintenance, management or replacement.

[0007] An objective of the invention is to overcome in whole or in part the disadvantages of the state of the art, in particular by improving their performance on these different points or the compromises between these different performances. Statement of the invention

[0008] The present invention is defined by the attached independent claim. Other preferred embodiments can be found in the dependent claims. The present application discloses a method for coding communication conductors of a linear sensor belonging to a system, the system comprising a central unit (8) and a plurality of linear sensors (500) each comprising a first end and a second end and which are connected together in series to form a differential bus, which is operatively connected to said central unit by at least one end of said differential bus, each linear sensor comprising at least: - a first connector (430) at a first end of said linear sensor, the first connector (430) comprising a management module (210) connected to a communication module (410), - a second connector (440) at a second end of said linear sensor, - two communication conductors (416),the two communication conductors being connected to the first connector (430) at a first end of said two communication conductors, and to the second connector (440) at a second end of said two communication conductors, characterized in that the method comprises the following steps: - coding of at least two information signals simultaneously as follows: at least one information signal being coded by the central unit (8) by increasing voltage T on the first communication conductor, at least one information signal being coded by the central unit (8) by decreasing voltage T on the second communication conductor, - reading of a voltage by the central unit by measuring the voltage difference between the two communication conductors, and in that the system also comprises at least one accessory making it possible to create a modular system., Description of figures and embodiments

[0009] Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments which are in no way limiting, and the following appended drawings: [ Fig. 1 ] illustrates a linear sensor, [ Fig. 2 ] illustrates an exemplary embodiment according to the invention, [ Fig. 3 ] describes another exemplary embodiment according to the invention, [ Fig. 4 ] describes another exemplary embodiment according to the invention.

[0010] These embodiments being in no way limiting, it will be possible in particular to consider variants of the invention comprising only a selection of characteristics described or illustrated subsequently isolated from the other characteristics described or illustrated (even if this selection is isolated within a sentence comprising these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, and / or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0011] There figure 1illustrates an example of the construction of a linear sensor that can be used within the scope of the invention. However, other types of linear sensors connected in series can be used within the scope of the invention, with all types of detection modes, and all types of communication and / or power supply buses. Linear sensors that are different from each other can also be used together within the scope of the invention, provided that their communication buses are compatible with each other and with the control unit.

[0012] In this example, each linear sensor 500 comprises a detector 200. This detector 200 comprises a management module 210, which is connected to the proximal end of a detection member 208 elongated over the entire length of the linear sensor 500. This detection member 208 forms a bundle which comprises two metal conductors 106 and 110 and two detection conductors 114, which are electrically connected two by two. The management module 210 measures the electrical properties of the detection conductors 114 using one of the metal conductors 106 and 110, called the measurement return wire. For detection of a conductive liquid such as, for example, water / acid base detection, the resistivity of the detection member decreases upon contact with said liquid. For detection of a non-conductive liquid such as a hydrocarbon or solvent, for example, the resistivity of the detection member increases upon contact with said liquid.

[0013] In addition to the sensor element 200, the linear sensor 500 comprises a communication element which includes on the one hand two communication conductors 416 and two power supply conductors 424 running along the entire length of the linear sensor 500. The two communication conductors have two-way communication. At the proximal end of the linear sensor 500, a connector 430 encloses the management module 210. The connector 430 also comprises a communication module 410 and a power supply module 420, which are connected to the communication conductors 416 and power supply 424 and together form a powered differential communication bus.

[0014] Each linear sensor 500 carries at its distal end a connector 440. The connector 440 comprises connection ports 444 and 446 which make it possible to connect the distal end of its power supply conductors 424 and respectively communication conductors 416 to the proximal end of another linear sensor of the same type.

[0015] The positions of the connectors 430 and 440 are not limiting. In some embodiments, the connector 440 is positioned on the proximal end of the linear sensor 500 and the connector 430 on the distal end of the linear sensor 500 for example.

[0016] At least two information signals are coded by the central unit 8 simultaneously on the two communication conductors as follows: at least one information signal is coded by the central unit by increasing the voltage T on the first communication conductor, at least one information signal being coded by the central unit 8 by decreasing the voltage T on the second communication conductor.

[0017] For example, one of the information signals is coded as a plus of five volts on a first information conductor while another information signal is coded as a minus of five volts on a second information conductor, and this simultaneously. The voltage values here are in no way limiting. They are given as an example. The different information signals are transmitted through all the linear sensors making up the network via the communication conductors of each linear sensor. A voltage reading is then taken by the control unit by measuring the voltage difference between the two communication conductors.

[0018] Information signals are transmitted in the form of information bits.

[0019] In reference to the figure 2 , we will now describe an exemplary embodiment.

[0020] The system or network presented consists of a central unit 8 and four linear sensors 5001 to 5004 connected in series and connected to the central unit 8 by one of the ends of the linear sensor 5001. The number of linear sensors is given for information purposes only and is therefore not limiting. The series of linear sensors forms an unlooped and closed detection line. It is closed by a cap. Each linear sensor comprises two communication conductors 416. The two communication conductors of each linear sensor are arranged to transmit different requests sent by the central unit 8. The two communication conductors are also arranged to transmit the responses to the different requests received to the central unit 8.

[0021] When the system starts, each element of the network, i.e. the linear sensors and the cap in this example, will automatically send a local RL request to the elements located upstream and / or downstream. The sending of local RL requests is done autonomously at startup. By "autonomous" we mean that the local requests are sent without a general request from the central unit beforehand. The different elements can send the local requests one after the other or by network section or all at the same time for example.

[0022] Indeed, initially and in the example presented, the linear sensor 5001 identifies the linear sensor 5002 downstream, the linear sensor 5002 identifies the linear sensor 5001 upstream and the linear sensor 5003 downstream, the linear sensor 5003 identifies the linear sensor 5002 upstream and the linear sensor 5004 downstream and finally the linear sensor 5004 identifies the linear sensor 5003 upstream (reference ID on the figure 2 ).

[0023] In a second step, each linear sensor 5001 to 5004 sends a local RL request to the linear sensors that they have each identified via the two communication conductors of each linear sensor. The local request is transmitted on each communication conductor simultaneously. In the example presented figure 2, the linear sensor 5001 sends a local RL request to the linear sensor 5002, the linear sensor 5002 sends a local RL request to the linear sensors 5001 and 5003, the linear sensor 5003 sends a local RL request to the linear sensors 5002 and 5004, and finally the linear sensor 5004 sends a local RL request to the linear sensor 5003.

[0024] The local requests RL are therefore sent by the two communication modules of each linear sensor 5001 to 5004 in the form of an interrogation signal. The communication conductors used for sending the local requests are the same as those used for sending the general requests RG. The local requests RL received are processed by the management module 210 of each linear sensor 5001 to 5004. All the linear sensors 5001 to 5004 process the local request RL that they have received and respond to it (reference RRL on the figure 2) by sending the responses via the two communication conductors. Each communication conductor sends the expected RRL responses following the local RL request sent. The different elements can respond to the local requests one after the other or by network section or all at the same time for example.

[0025] Each detector 200 internal to each linear sensor includes a unique identifier that allows it to be identified. The unique identifier corresponds to the serial number of the detector 200 of each linear sensor, for example. When a linear sensor responds to a local RRL request, it communicates its unique identifier to the linear sensor that sent the local RL request. For example, the linear sensor 5001 sends its unique identifier in response to the local RRL request of the linear sensor 5002, the linear sensor 5002 sends its unique identifier in response to the linear sensors 5001 and 5003, the linear sensor 5003 sends its unique identifier in response to the linear sensors 5002 and 5004, and finally the sensor 5004 sends its unique identifier in response to the linear sensor 5003. The unique identifiers are sent via the two communication modules of each linear sensor 5001 to 5004.

[0026] In a preferred embodiment, the central unit 8 sends a general query RG to all the linear sensors 5001 to 5004 as well as to the plug in order to obtain all the unique identifiers of the elements which make up the network as well as the unique identifiers identified by the different elements of the network, that is to say the elements which are upstream / downstream of the elements and / or which are connected to the different elements. This general query RG will allow the central unit to reconstruct the architecture of the network or system.

[0027] The general RG request is transmitted through the network via the two communication conductors of each linear sensor in the center - tail direction. That is, the general RG request is sent on both communication conductors simultaneously.

[0028] The general request RG is received by each communication module of each linear sensor 5001 to 5004. The general request RG is processed by the management module 210 of each linear sensor. The general request RG is transmitted in the form of an interrogation signal by the central unit 8 to the different linear sensors via the communication conductors of each linear sensor. The number of general requests is not limited. The first communication conductor operates identically to the second communication conductor and vice versa. The general request RG has been sent on each of the two communication conductors and consequently each communication conductor allows the responses to the general request RRG received to be returned to the central unit.

[0029] First, the central unit 8 sends a general RG request to all the linear sensors 5001 to 5004 as well as to the plug. In response to the general RG request sent by the central unit 8, each element of the network sends its unique identifier as well as the unique identifier of the elements located upstream / downstream of it obtained thanks to the various local RL requests sent during the system startup.

[0030] Therefore, each linear sensor transmits to the central unit 8 its unique identifier (response to the first general RRG request) as well as the unique identifiers of the linear sensors that they have identified (response to the second general RRG request). For example, in the case presented, to respond to the general RRG request, the linear sensor 5001 sends to the central unit its unique identifier as well as that of the linear sensor 5002, the linear sensor 5002 sends to the central unit 8 its unique identifier and the unique identifiers of the linear sensors 5001 and 5003, the linear sensor 5003 sends to the central unit its unique identifier as well as the unique identifiers of the linear sensors 5002 and 5004, and finally the linear sensor 5004 sends to the central unit 8 its unique identifier as well as that of the linear sensor 5003. The responses to the general RRG request are transmitted in the form of a response signal to the central unit 8.

[0031] In this preferred embodiment, the general request RG sent also makes it possible to send specific data to the central unit 8. specific to network elements. In this case, each network element sends a new local request to the upstream and / or downstream elements. The response to the local RRL request from each linear sensor or accessory such as the cap then includes the specific data requested by the general RG request which are specific to the different network elements. The responses to the different local requests can include one or more specific data. Specific data are for example: a linear sensor commissioning date, the linear sensor type, a linear sensor length, a linear sensor internal loop resistance, a pollution level, an alarm status, a power supply level.

[0032] Specific data is not limited to this list. Specific data is in other embodiments historical data, or sensitivity data for example.

[0033] Each linear sensor includes a commissioning date. This specific data is stored in the management module 210 of said linear sensor, for example. The same applies to the type of linear sensor and its length. This specific data is therefore transmitted to the central unit 8 during the response steps to a local RRL request or during a response to a general RRG request via the two communication conductors of each linear sensor.

[0034] In the expression "internal loop of the linear sensor" internal loop resistance of the linear sensor, we mean a loop formed by one of the metallic conductors and a measurement return wire in a linear sensor (references 106 and 110 on figure 1). The resistance of an internal loop therefore corresponds to the state in which it is found. In the event that, for example, the metal conductor or the return wire is cut, damaged, or for any other reason the internal loop is no longer functional, an alarm state of the linear sensor corresponding to a discontinuity alarm is sent to the control panel 8 to warn the user.

[0035] The detection drivers 114 ( figure 2) include a resistor (not shown in the figures) which makes it possible to define whether a break in the detection member 208 has occurred. By "a pollution level" is meant the pollution level of said resistance of the detection conductors 114. Indeed, during the use of a linear sensor, dust may be deposited on the resistance, for example, or the resistance may deteriorate due to the environmental conditions in which it is located. In this case, an alert state of the linear sensor corresponding to a cleaning alert is sent to the central unit 8 to warn the user for example.

[0036] An alarm status is sent if one of the previously described conditions occurs via the communication conductors. The alarm status is also activated based on a network sensitivity level. This sensitivity level is defined based on specific pollution and / or internal loop resistance data sent to the control panel. To achieve this, a sensitivity threshold is previously defined for each linear sensor or for the network as needed. For example, the sensitivity threshold is set between one and five if it is an individual sensitivity threshold, specific to each linear sensor, or to zero if it is an overall network sensitivity threshold.

[0037] The power supply level of a linear sensor is defined by the power supply module 420. The two power supply conductors 424 are responsible for transmitting the power supply through the network. However, the power supply range is limited to a certain distance of linear sensors, i.e. a certain cable length. Therefore, the power supply level of each linear sensor is transmitted when a general request RG is sent by the central unit and / or when a local request RL is sent by one of the linear sensors.

[0038] In the case where the central unit 8 identifies a linear sensor with a power supply level that is too low, i.e. below a predetermined threshold, an alert status is sent by the management module 210 of the linear sensor in question to the central unit 8. The central unit 8 then sends a message to the user so that he can intervene on the network. For example, if the network power supply is equal to twelve volts, the predetermined threshold may be around ten volts - ten and a half volts. The central unit can also signal to the user that there are too many elements on the loop. The user can then intervene and remove elements or add an external power supply if possible.

[0039] In the event of a break or failure on one of the linear sensors, it goes into alarm mode. The management module of the linear sensor in alarm mode then transmits this specific data to the control unit in response to the general RRG request or the local RRL request of a linear sensor.

[0040] When all the responses to the local RRL requests have been sent and processed by the linear sensors, each linear sensor 5001 to 5004 responds to the general RRG request sent by the central unit 8 (referenced RRG on the figure 2 ) via the two communication conductors of each linear sensor in the cap-to-center direction, the communication conductors being the same as those which transmit the interrogation signals.

[0041] In the preferred embodiment presented here, a single general request RG is sent by the central unit 8 in order to receive the unique identifiers of each element of the network as well as specific data allowing the central unit 8 to know, for example, the type of element which forms the network, or the state in which it is found.

[0042] Communication via the communication conductors of each linear sensor allows the control panel 8, based on the specific data received as well as the unique identifiers of the network elements, to directly determine which linear sensor is in alarm status and where it is located in the network, for example.

[0043] The two communication conductors of each sensor then allow communication between the central unit and all the elements of the network, this communication being two-way (central unit plug / central plug) on the two communication conductors of each linear sensor. The two-way communication conductors work from each of its ends, that is to say for example, from end one to end two and vice versa and / or from end two to end one and vice versa.

[0044] In a second embodiment, the central unit 8 sends two separate general RG requests in order to send back, on the one hand, the unique identifiers of each element and, on the other hand, the specific data specific to each element.

[0045] Initially, when starting the network, the central unit 8 sends a first general request RG to all the linear sensors 5001 to 5004 in order to obtain all the unique identifiers included in each element that make up the network as well as the unique identifiers identified by the different elements of the network, i.e. the elements that are upstream / downstream of the elements and / or that are connected to the different elements. Following this first general request RG, each element of the network, i.e. the linear sensors and the plug in this example, will send a local request RL to the elements located upstream and / or downstream. In this embodiment, the sending of local requests by the elements of the network is not done autonomously but on request. On the same principle as presented in the preferred embodiment, all the elements of the network respond to the different local requests RL sent.Once all the local RL requests have been processed, the network elements respond to the first general RG request, still according to the same principle as that presented in the preferred embodiment.

[0046] In a second step and if necessary, the central unit sends a second general RG request in order to obtain the various specific data specific to each element of the network. The specific data are the same as those presented in the preferred embodiment. Sending the second request works on the same principle as sending a single general RG request as presented in the preferred embodiment.

[0047] Central 8 then receives all the responses to the RRG general requests (the first as well as the second), and processes them. The responses to the general requests are therefore adapted to the type of general request sent.

[0048] In Fig.3Another exemplary embodiment of the invention is illustrated. In this example, the different requests correspond to interrogation signals. The different responses to the different requests correspond to response signals.

[0049] The network consists of a central unit 8 comprising two connectors 81 and 82 connected to a series of linear sensors forming the loop B1 via the connectors of the linear sensors located at the ends of said series. The loop B1 comprises branches B1N2, B1N3 and B1N6, which receive two series of linear sensors forming the secondary loops B2 and B3.

[0050] These derivations B1N2, B1N3 and B1N6 are formed by an electronic derivation module, which is arranged to receive in at least one of its outputs, the connector of one or more linear sensors, potentially of the same type but not necessarily.

[0051] In this example, each of these derivations are located at one of the connectors of a linear sensor, for example in the housing which contains the communication module 410 (see figure 1 ). Connector 4302 thus contains a B1N2 branch, connector 4303 contains a B1N3 branch, and connector 4306 contains a B1N6 branch.

[0052] Within a linear sensor, each of the branches is operatively connected to the communication module 410 and consequently to the two communication conductors, which transmits to it the interrogation signals E1, E2 that it receives via the communication conductors, in addition to transmitting them to the adjacent linear sensor. The branch is arranged to transmit the interrogation signal to a derived linear sensor via a branch box.

[0053] Thus, the differential bus (called loop of rank one or loop B1) carries a derivation called simple B1N2, equipped with a derivation box 821 on which is connected one of the ends of a second differential bus (called loop of rank two or loop B2). The primary loop B1 also carries a second derivation simple B1N3, equipped with a second derivation box 822 on which is connected the second end of the secondary loop B2.

[0054] Each branch and / or accessory of the network sends a response signal including data specific to said branch and / or accessory at the same time as it and / or the latter transfers the response signals from the second differential bus to the central unit.

[0055] Via this junction box 821, the branch B1N2 relays in the form of first interrogation signals E21 in the loop B2, the first interrogation signals E1 received in the connector 4302 sent by the interrogation port 81 through the communication conductors of the loop B1. The branch B1N2 is also arranged to receive via its junction box 821 the response signals R21 sent by the communication conductors of the loop B2 in response to the interrogation signals E21, and to relay them in the primary loop B1 in the form of response signals R1. The response signals R21 are transmitted to the interrogation port 81 of the central unit which emitted the interrogation signals via the communication conductors of the loop B1. It is understood here that the communication conductors of the linear sensors operate in the same manner as that presented in the embodiment of the figure 2 .

[0056] Via this junction box 822, the branch B1N3 relays in the form of first interrogation signals E22 in the loop B2, the first interrogation signals E2 received in the connector 4303 sent by the interrogation port 82 via the communication conductors of the loop B1. The branch B1N3 is also arranged to receive via its junction box 822 the response signals R22 sent by the communication conductors of the loop B2 in response to the interrogation signals E22, and to relay them in the primary loop B1 in the form of response signals R2. The response signals R22 are transmitted to the interrogation port 82 of the control unit which sent the interrogation signals via the communication connectors of the loop B1.

[0057] This primary loop B1 also carries a third branch B1N6, called double. The latter operates in the same way as the single branches, except that it combines and manages both a first branch box 831 and a second branch box 832 to which the two ends of a second secondary loop B3 (itself also of rank two) are connected. Each of these branch boxes 831, 832 transmits first and second interrogation signals E31 and E32 to it, and receives first and second response signals R31 and R32 from it.

[0058] As understood, the first and second junction boxes of said junction B1N6 of loop B1 are seen by loops B2, B3 in a similar manner to the interrogation ports 81, 82 of the central unit 8.

[0059] The branch B1N6 is therefore arranged to receive, through its branch box 831, the response signals R31 sent by the communication conductors of the loop B3 in response to the interrogation signals E31, and to pass them on to the primary loop B1 in the form of response signals R1 via the communication conductors of the loop B1. The response signals R31 are transmitted to the interrogation port 81 of the control unit which sent the interrogation signals.

[0060] The B1N6 branch is also arranged to receive through its branch box 822 the response signals R32 sent by the linear sensors of the loop B3 in response to the interrogation signals E32 via the communication conductors of the loop B3, and to pass them on to the primary loop B1 in the form of response signals R1 via the communication conductors of the loop B1. The response signals R32 are transmitted to the interrogation port 82 of the control unit which issued the interrogation signals.

[0061] We see that it is thus possible to create numerous topologies, combining loops of different ranks, in a very flexible way, both with regard to the areas to be monitored and from the point of view of modifications to the installation during its lifetime. These advantages are obtained while benefiting from the redundancy and fault location that the individual operation of each loop allows, all the information from which ultimately goes back to the central unit 8 thanks to the two-way communication conductors of each linear sensor.

[0062] In Fig.4Another example embodiment of the invention is illustrated, in which a set of sensors 5001 to 5006 (here six as an example but this number is not limited) are connected together in series, to form a loop, here called a simple loop which is connected by its two ends 4301 and 4406 to the central unit 8. This loop corresponds to a level one loop. This loop also forms a differential interrogation bus.

[0063] This loop uses for example linear sensors such as that of the Fig. 1 , without this being in any way limiting to the types of linear sensors that can be implemented.

[0064] The central unit 8 carries a first interrogation port or communication port 81 and a second interrogation port or communication port 82. On the first interrogation port 81 is connected the first linear sensor 5001 of the differential interrogation bus, by means of its proximal connector 4301. The last linear sensor 5006 is connected by its distal connector 4406 to the second interrogation port 82. Each linear sensor composing the differential interrogation bus comprises two communication conductors. Communication on the two communication conductors is two-way. The communication conductors presented here operate in the same manner as that presented in the embodiment of the figure 2 Or 3 .

[0065] The first interrogation port 81 of the central unit 8 interrogates all the linear sensors of the loop B1 by transmitting a first interrogation signal E1 through each communication conductor of each linear sensor. It receives a first series of response signals R1 returned by all the linear sensors, in response to this first interrogation signal E1 via each communication conductor of each linear sensor. Once all the response signals are received by the interrogation port 81, the second interrogation port 82 of the central unit 8 also interrogates all the sensors of the loop B1 by transmitting a second interrogation signal E2 via each communication conductor of each linear sensor. It receives a second series of response signals R2 returned by all the linear sensors of the loop B1, in response to this interrogation signal E2 via each communication conductor of each linear sensor.

[0066] The interrogation signals E1, E2 and response signals R1, R2 are transmitted by each communication conductor of each linear sensor of the loop B1 independently of each other but preferably simultaneously. Each communication conductor of each sensor is traversed by two interrogations / responses: on the one hand E1-R1, and on the other hand E2-R2, there is therefore a two-way communication.

[0067] The control panel 8 then compares the response signals from both ends. In the case where no break or fault is present on the differential interrogation bus, the control panel finds no difference when comparing the response signals.

[0068] In the case where a break 900 or a failure occurs on one of the linear sensors (here 5002) of the differential interrogation bus, the linear sensor in question 5002 is capable of responding either upstream or downstream, the management module thereof remaining powered by the upstream or downstream of the loop (case of a single break). The first interrogation port 81 therefore receives a response signal from the linear sensors located upstream, here the response signal from the linear sensor 5001 and, if the linear sensor 5002 is powered by the upstream according to the direction of the interrogation E1, the response signal from the linear sensor 5002. The following ones do not receive the first interrogation signal E1, and cannot respond to it.Once all the response signals are received by the interrogation port 81 via the communication conductors of each linear sensor, the second interrogation port 82 interrogates from the other end of the loop B1 the linear sensors of the differential interrogation bus via the communication conductors of each linear sensor, and receives the response signals from the linear sensors which are upstream of the break / failure 900 with respect to the direction of the interrogation signal E2. It therefore receives response signals from all the other linear sensors following 5006, 5005, 5004, and 5003 of this same loop B1. And if the linear sensor 5002 is powered from upstream according to the interrogation direction E2, the response signal from the linear sensor 5002. The power bus is configured so that each module 4301 to 4306 is powered both upstream and downstream.

[0069] Thus, the central unit 8 which interrogates the differential interrogation bus which it sees downstream receives response signals from all the linear sensors still in working order via the two communication conductors.

[0070] Furthermore, the dual interrogation bus E1-R1 (solid arrows) and E2-R2 (hollow arrows) comprising the two communication conductors of each sensor is organized so that the central unit 8 can identify the linear sensor at the origin of each response. For example, regardless of the interrogation signal E1 or E2 that the central unit receives, the communication modules of the linear sensors 5001 to 5006 are arranged to transmit their response signals with at least one identification data, which allows the central unit 8 to identify the sensor at the origin of each response.

[0071] In the case of a break or failure, for example deduced by the central unit 8 from the fact that it does not receive enough response signals or that it only receives one from each linear sensor instead of two via the communication conductors, the central unit 8 will identify which response signals arrive via each of its interrogation ports 81 and 82. In the example of the break 900 of the Fig.4, the first interrogation port 81 receives the response signal from the first linear sensor 5001, if the linear sensor 5002 is supplied from upstream in the direction of interrogation E1, the response signal from the linear sensor 5002. The second interrogation port 82 receives the response signals from the linear sensors 5003 to 5006 and if the linear sensor 5002 is supplied from upstream in the direction of interrogation E2, the response signal from the linear sensor 5002. The central unit 8 compares the response signals received by each interrogation port of the central unit and deduces that the faulty linear sensor is the linear sensor located between the last linear sensor of the first bus E1-R1 and the last linear sensor of the second bus E2-R2, and therefore that it is the linear sensor 5002. In the event of breaks, the central unit 8 determines which portion of the loop B1 is not responding on the same principle.

[0072] Here it must be understood that if the power supply to a linear sensor is cut off due to a failure or break, the communication in the differential bus is cut off. That is to say, the two-way communication of the communication conductors "stops" at the level of the failure or break. One of the advantages of the invention is that the two-way communication is applied to each end of the differential bus making it possible to define where the failure or break is located.

[0073] Typically, each of the means of the device according to the invention previously described may comprise at least one computer, a central or calculation unit, an analog electronic circuit (preferably), a digital electronic circuit (preferably), and / or a microprocessor (preferably), and / or software means.

[0074] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0075] Of course, the various features, forms, variants and embodiments of the invention may be combined with each other in various combinations provided that they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above may be combined with each other.

Claims

1. Method for coding communication conductors of a linear sensor belonging to a system, the system comprising a central unit (8) and a plurality of linear sensors (500) each comprising a first end and a second end and which are connected to one another in series to form a differential bus, which is functionally connected to said central unit by at least one end of said differential bus, each linear sensor comprising at least: - a first connector (430) at a first end of said linear sensor, the first connector (430) comprising a management module (210) connected to a communication module (410), - a second connector (440) at a second end of said linear sensor; - two communication conductors (416), the two communication conductors being connected to the first connector (430) at a first end of said two communication conductors, and to the second connector (440) at a second end of said two communication conductors; the method comprising the following steps: - coding at least two information signals simultaneously as follows: at least one information signal being coded by the central unit (8) by increasing voltage T on the first communication conductor; at least one information signal being coded by the central unit (8) by decreasing voltage T on the second communication conductor; - the central unit reading a voltage by measuring the voltage difference between the two communication conductors; and the system also comprises at least one accessory allowing a modular system to be created.

2. Method according to claim 1, characterized in that the system also comprises at least one accessory corresponding to a branch, the accessory comprising at least one output.

3. Method according to claim 1 or 2, characterized in that the system also comprises at least one accessory corresponding to a terminator.

4. Method according to claim 1 or 2 or 3, characterized in that the system also comprises at least one accessory corresponding to a neutral cable.

5. Method according to according to any one of the preceding claims, characterized in that the information signal is sent by the central unit in the form of information bits.

6. Method according to claims 2 to 5, characterized in that the central unit is arranged to send at least one general request to the differential bus and to receive at least one response to said general request from the plurality of linear sensors and the at least one accessory, the method also comprising the following steps: - communicating the at least one general request (RG) sent by the central unit through the plurality of linear sensors (5001 to 5004) and / or the at least one accessory via the two communication conductors; and - communicating the at least one response to the general request (RRG) sent by said plurality of linear sensors (5001 to 5004) and / or by the at least one accessory via the two communication conductors.

7. Method according to claim 2 and according to any one of the claims 3 to 6, characterized in that each linear sensor and / or accessory is arranged to send at least one local request and to receive at least one response to the at least one local request from each linear sensor and / or accessory, the method further comprising the following steps: - communicating, via the two communication conductors, the at least one local request (RL) to at least one linear sensor identified by said linear sensor (5001 to 5004) and / or by the at least one accessory, the at least one linear sensor being considered as identified if one of its connectors (430 or 440) is connected to one of the connectors (430 or 440) of said linear sensor and / or to the at least one output of the at least one accessory; and - communicating, via the two communication conductors, at least one response to at least one local request (RRL) from the linear sensor identified by said linear sensor (5001 to 5004) and / or accessory.

8. Method according to claim 2 and according to any one of the claims 3 to 7, characterized in that each linear sensor (5001 to 5004) and / or accessory is characterized by a unique identifier.

9. Method according to claim 8, characterized in that the at least one response to the at least one general request sent by the linear sensor comprises the unique identifier of the at least one linear sensor identified by said linear sensor as well as the unique identifier of said linear sensor (5001 to 5004), and / or the at least one response to the at least one general request sent by the accessory comprises the unique identifier of the at least one linear sensor identified by said accessory as well as the unique identifier of said accessory.

10. Method according to claim 7 and according to any one of the claims 8 to 9, characterized in that the at least one response to the local request (RRL) is composed of the unique identifier of the at least one linear sensor identified by said linear sensor (5001 to 5004) and / or the accessory.

11. Method according to claim 7 and according to any one of the claims 8 to 10, characterized in that the at least one response to the local request (RRL) and the at least one response to the general request (RRG) also comprise data specific to each linear sensor (5001 to 5004) and / or accessory.

12. Method according to any one of the preceding claims, characterized in that communication on the communication conductors is two-way.

13. System for implementing the method according to any one of the preceding claims 2 to 12, the system comprising a central unit (8) and a plurality of linear sensors (5001 to 5004) each comprising a first end (430) and a second end (440) and which are connected to one another to form a sensing line, which is connected to said central unit (8) by at least one end of said sensing line, the system also comprising at least one accessory.

14. Computer program product comprising instructions which, when the program is executed by a computer, cause the latter to implement the steps of the method according to any one of the claims 1 to 12.