WO2014131769A1

WO2014131769A1 - Device for communication by coding of current with a plurality of monitoring modules and monitoring system comprising such a device

Info

Publication number: WO2014131769A1
Application number: PCT/EP2014/053656
Authority: WO
Inventors: Stéfan BALATCHEV
Original assignee: Valbatech
Priority date: 2013-02-26
Filing date: 2014-02-25
Publication date: 2014-09-04
Also published as: FR3002710A1

Abstract

The invention relates to a device (102) for communication by coding of current with a plurality of modules (104), termed monitoring modules, disposed in an environment to be monitored, said device (102) comprising: - a so-called central unit (106), comprising an electrical generator (110), and at least one so-called receiver means (114), for measuring the current provided by said electrical generator (110, 210); - at least one electric wire (108), termed a communication wire, designed to link said central unit (106) to each of said monitoring modules (104); and - for each monitoring module (104), at least one so-called short-circuit means (118-124), that can be displaced between: - an open position in which the current delivered by said electrical generator (110, 210) does not pass over said communication wire (108) downstream of said monitoring module, and - a closed position in which the current delivered by said electrical generator is no longer consumed by said monitoring module and passes downstream of said monitoring module; so that each monitoring module (104) is linked to said communication wire (108) in turn. It also relates to a detection system comprising such a communication device.

Description

"Current coded communication device with a plurality of monitoring modules and monitoring system comprising such a device" Technical field

The present invention relates to a current coding communication device with a plurality of monitoring modules for monitoring an environment to be monitored. It also relates to a system implementing such a device.

The field of the invention is the field of devices for transmitting information or multi-subscriber data between monitoring sensors, in particular pressure, temperature, flame, smoke, and liquid leak detection sensors. or gas, placed in an environment to monitor and one or more receivers to receive and process this information. More particularly, the field of the invention is the field of multi-subscriber industrial communication buses enabling several sensors to transmit to a central unit information relating to a detection or measurement carried out by said sensors in an industrial environment to be monitored. .

State of the art

Cable data transmission between monitoring or measurement sensors installed in an industrial environment to be monitored is provided by fieldbus such as RS-422, RS-485, Profibus, etc. In order to guarantee a better tolerance to electrical disturbances, multi-subscriber industrial buses are based on differential voltage variations. A power supply is applied to each node to provide the electrical power for the operation of the device and the bus itself.

Immunity to electromagnetic interference can be enhanced by using a current loop. The current loop is a circuit for transmitting the information of a sensor in the form of a current. Its particularity comes from the fact that the power supply, the conditioner, the sensor and any other electrical element connected to the sensor are all connected in series in a mesh, also called loop, unique.

The current loop allows communication with a sensor over lengths greater than 1 km, while having a better immunity to noise since parasitic voltages, such as inductive or thermoelectric fem, do not contribute much to the loop current due to the large internal impedance of the current generator which is in series with the line.

Moreover, a current loop makes it possible with only two electrical wires to perform both the sensor supply and the coding of the information and makes it possible to have several receivers to receive the information transmitted by the sensor.

The big drawback of the current loop is the impossibility of connecting several transmitters in the same loop. In other words, the current loop does not allow a multi-subscriber mode to interrogate several sensors. This disadvantage severely limits its applications as an information transmission bus.

The invention aims to overcome the aforementioned drawbacks.

Another object of the invention is to provide a multi-subscriber communication device having a better immunity to noise and allowing an information transmission over long distances.

It is also an object of the invention to provide a multi-subscriber communication device for performing a less expensive monitoring system.

Presentation of the invention

The invention makes it possible to achieve at least one of the aforementioned objects by a current coding communication device with a plurality of so-called monitoring modules arranged in an environment to be monitored, said device comprising:

a unit, called a central unit, in particular arranged at a monitoring site, comprising: ^■ an electrical generator, one terminal, so-called minimum, is at a first electrical potential, said smaller, and the other terminal is at a second electrical potential, said largest and

At least one means, said receiver, for measuring the current supplied by said electric generator, in particular disposed between said electric generator and said control modules;

at least one electrical wire, referred to as a communication wire, designed to connect said central unit to each of said modules and to transport, to each of said modules, the current delivered by said electric generator; and

for each monitoring module, at least one means, called a short-circuit, that can be moved between:

An open position in which the current delivered by said electrical generator does not pass over said communication wire downstream of said monitoring module and is consumed by said monitoring module, in this open position the monitoring modules located downstream of said module therefore, a closed position in which the current delivered by said electric generator passes over said communication wire downstream of said monitoring module, so that said monitoring module does not consume. , or almost not, the current delivered by said electric generator;

so that each module is connected to said communication wire, and therefore to said CPU, in turn, and only one monitoring module is connected to the CPU at a time.

Thus, the device according to the invention makes it possible to carry out current coded communication with a plurality of monitoring modules. Thus, the device according to the invention exploits all the advantages a current loop without being limited to a single-ended communication, that is to say to a communication with a single sensor. Consequently, the device according to the invention makes it possible to carry out a robust multi-subscriber communication and this over distances greater than 10,000 m.

In addition, the communication device according to the invention makes it possible to carry out, with the same wire (s), both the transmission of the information from the monitoring modules and the power supply of the monitoring modules, thereby avoiding provide one or more power supply wire (s) for the monitoring modules in addition to the communication wire (s). Consequently, the device according to the invention makes it possible to produce a monitoring system which is less expensive and simpler to manufacture and install.

By electrical generator is meant a voltage generator, in particular a voltage generator at the terminals of which the voltage is constant and the delivered current is variable, or a current generator used in an operating mode in which the delivered current is variable. when the voltage at the terminals of said current generator is greater than its limit voltage, also known as the conformity voltage of the current generator, or any combination of a current generator with a voltage generator.

In a non-limiting version, the electrical generator may be arranged to limit the current delivered to a predetermined maximum value or coupled to a device, for example an electronic device such as a resettable fuse or a single-use fuse, limiting the current delivered to said maximum value. . Thus, the electric current, and more generally the electrical energy, delivered by the electric generator is limited (s), for example in case of malfunction of one or more sensors, or in case of short circuit between the wire of communication and mass or a ground wire.

In addition, the electrical generator may be arranged to deliver a current and / or a voltage such that it takes into account the resistance represented by the total length of the communication wire. In that case, each monitoring module or the short-circuit means associated with a monitoring module, may comprise an electric regulator configured to absorb / eliminate the excess voltage or current, emitted by the electrical generator, and corresponding to the length of the wire of downstream communication of the monitoring module with respect to the electric generator.

According to a non-limiting exemplary embodiment, when the short-circuit means associated with a monitoring module are in the closed position, the monitoring module can consume a current of value less than or equal to 2 mA and preferably 1 mA. Still according to this example, when the short-circuit means associated with a monitoring module are in the open position, the monitoring module can consume a current of value greater than or equal to 3 mA, preferably greater than 1 mA, in particular between 3 mA, preferably 1mA, and 50 mA.

According to the invention, the monitoring modules are connected on the one hand to the communication wire which is at a greater potential, and on the other hand to a smaller potential, called electrical ground, so that they are arranged in parallel to each other.

Advantageously, the device according to the invention may further comprise means for controlling the start and / or end of the transmission of a variable current on the communication wire by the electric generator.

Such a control means can be a means performing the starting and stopping of the electric generator.

Such a control means may preferentially be a short circuit means, and in particular a switch, which in an open position connects the electrical generator with the communication wire, and in a closed position, no longer connects the electric generator with the communication wire.

According to a particular embodiment, but in no way limiting, the device according to the invention may comprise a single communication wire, put to the greatest electrical potential, says positive potential. In this case, the smallest potential, called electrical ground, is earth.

According to another particular embodiment, but in no way limiting, the device according to the invention may comprise a second electrical wire, called a ground wire, intended to connect said central unit to each of the monitoring modules, the communication wire being connected to a terminal of the central unit set to a larger electrical potential, said positive potential, and the ground wire being connected to a terminal of the central unit set to a smaller electric potential, said electric ground.

In this case, each monitoring module is connected on the one hand to the communication wire and on the other hand to the ground wire, so that the monitoring modules are arranged in parallel with each other. Advantageously, the device according to the invention may further comprise at least one means, termed termination, connected to the distal end of the communication wire relative to the central unit, and provided for the detection of the end of a communication cycle, that is to say when the last monitoring module has transmitted the desired information to the central unit.

In a particular version, but in no way limiting, the device according to the invention may comprise two central units, each connected to one end of the communication wire.

Thus, each central unit emits a current on the electrical wire in a first direction, opposite to the direction of the variable current emitted by the other central unit.

Concretely, the communication wire connects or connects, in order, a central unit, then the monitoring modules and finally the other central unit, so that the monitoring modules are connected to the communication wire between the two units power stations.

In this version, the two central units initiate and realize, each in turn, a polling cycle of the monitoring modules, in two opposite directions. This version, called the redundant version, allows the interrogation of all the monitoring modules in case of interruption or short-circuit of the communication wire, or in the event of failure of a central unit. In the redundant version of the device according to the invention, at least one, preferably each, central unit may comprise at least one means for detecting the end of transmission of a current emitted or consumed on the communication wire by the electric generator. from the other unit.

Such detection means may be a measuring means, and possibly monitoring a current emitted or consumed by the other CPU. The detection means monitors the current emitted or consumed by the other CPU. As soon as the latter is detected, the detection means waits for the value of the current emitted or consumed to be zero. When the value of the current sent or consumed by the other central unit is zero, this means that the other central unit has / has been put on standby, or that the interrogation cycle carried out by the other CPU by a triggering means.

In its redundant version, the device according to the invention may comprise terminating means associated with each central unit, on the side of the other central unit.

In particular, the termination means associated with a central unit can be integrated in the other central unit.

The termination means associated with a central unit can be integrated in the detection means of the other the central unit.

In its redundant version, the device according to the invention may comprise, for each central unit, means for controlling the start and / or end of transmission of a variable current on the communication wire by the electrical generator of said unit Central.

In its redundant version, the device according to the invention may further comprise means for synchronizing the two central units together. The means of synchronization of the two central units together may comprise an electrical wire, called synchronization, connecting the two central units, or synchronization means wireless or in-line carrier, and so on.

The synchronization means may alternatively or additionally comprise automatic means such as semaphore synchronization, slot sharing, random number generator, etc.

Advantageously, the two central units can be synchronized by a master / slave protocol, such that one of the central units is the master central unit and the other the central slave unit. At first, the slave CPU is idle but remains connected to the sensor network. The master CPU continuously monitors the sensor array, and when a break is detected, the master CPU sends an enable command to the slave CPU that supports the monitoring of the cut sensors in the communication. with the master CPU. When network continuity is restored, the slave CPU is put back into sleep mode, for example following a command sent by the master CPU, and goes into standby mode.

In its redundant version, the device according to the invention may comprise, for at least one, in particular each, monitoring module, at least one means / module, called anti-collision, for detecting a simultaneous transmission on the communication wire:

a current supplied from the upstream of said monitoring module, and

a current supplied from the downstream of said monitoring module. In other words, the means / anti-collision module makes it possible to detect the supply of the communication wire simultaneously by the two central units, such a situation being called in the following description a collision.

The collision avoidance module can be used instead of the sync wire or in addition to the sync wire.

The collision avoidance module can be integrated into the monitoring module. Alternatively, the collision avoidance module can be integrated with the short-circuit means.

Alternatively, the collision avoidance module may not be integrated, either in the monitoring module or in the short-circuit means, and may be in the form of an independent module.

The collision avoidance module may comprise at least one logic element arranged to emit a specific signaling when it detects the presence:

an electrical supply signal on the communication wire upstream of the monitoring module, and in particular upstream of the short-circuit means, and

- An electrical supply signal on the communication wire downstream of the monitoring module, and in particular downstream of the short-circuit means.

Such a logic element may be for example, but not limited to, an "AND" logic element connected to the communication wire upstream and downstream of the monitoring module, and in particular short-circuit means. Such a logic element delivers a signal of a value "1" when it detects a signal upstream and downstream.

Of course, other logical elements, for example one or more logical elements of the "OR", "exclusive OR", "NAND", "NON-OR", etc. type. can be used to achieve the same result. The collision avoidance module may further comprise at least one means for signaling to at least one, preferably each central unit, the collision, that is to say the fact that it feeds the communication wire at the same time as other CPU.

Such a signaling means may comprise at least one electrical load which can be connected to the communication wire and which makes it possible to transmit a signaling of the collision by current coding. In another non-limiting version, the so-called loop version, the communication wire may be connected to the central unit at its two ends, said device further comprising at least one means for selecting a direction of transmission of the current supplied by said central unit on said communication wire in one direction or the other.

In this embodiment, the device according to the invention allows with a single central unit, to interrogate and communicate with the monitoring modules connected to the communication wire, in both directions.

The loop version allows, with a single central unit, the interrogation of the monitoring modules and the communication with them in case of interruption or short circuit of the communication wire. This version therefore ensures communication with all monitoring modules, while being less expensive to produce, and easier to install.

According to a particular embodiment, the selection means may comprise a switch which, in a first position, connects the central unit to one end of the communication wire, and in a second position, to the other end the communication wire.

Such a switch can be controlled by the central unit or by an external module or device.

The switch can also have a completely autonomous operation and switch automatically from one position to another after a predetermined time, for example by using an integrated timer.

In its loop version, the device according to the invention may comprise, for at least one, preferably each direction of emission of the current on the communication wire, at least one end of current emission detection means in said meaning.

Such a means of detecting the end of current transmission may be identical to that described above, for the redundant version.

Preferably, the means for detecting the end of emission of a variable current in one direction, preferably in each of the directions, can be connected to the distal end of said communication wire in said direction.

Preferably, the end of emission detection means associated with a direction, preferably with each direction, of emission can be integrated in the central unit.

In its loop version, the device according to the invention may further comprise termination means associated with each direction of current emission in the communication wire disposed on the side of the distal end of said communication wire in said direction. resignation.

Preferably, the termination means associated with a transmission direction can be integrated into the detection means associated with said transmission direction.

The device according to the invention may, in its loop version, comprise an anti-collision module as described above, for detecting and possibly signaling a collision due to the transmission by the single central unit of a signal on the wire of communication in both directions. Such a collision may appear for example in case of malfunction of the selection means.

At least one short-circuit means may comprise at least one, advantageously two switches, and preferably three switches.

The short-circuit means may comprise at least one diode, preferably two diodes.

At least one receiver may comprise a current measuring means such as at least one ammeter. Advantageously, at least one, in particular each, monitoring module may comprise several measuring / monitoring blocks each dedicated to measuring / monitoring a predetermined parameter. For example, a / each monitoring module may comprise a monitoring block for measuring a humidity level, another dedicated to measuring a concentration of sensor monoxide, etc.

Alternatively or additionally, several measurement / monitoring blocks of the same monitoring module can measure / monitor the same parameter, for example in order to avoid false alarms due to the malfunction of a measurement / monitoring block.

In addition, the device according to the invention may further comprise, for at least one, in particular each, monitoring module, at least one means / module, called switching, for controlling / switching the short-circuit means associated with said monitoring module.

The switching module can be integrated into the monitoring module.

Alternatively, the switching module can be integrated with the short-circuit means that it controls.

Alternatively, the switching module may not be integrated either in the monitoring module or in the short-circuit means and may be in the form of an independent module.

Such a switching module makes it possible to avoid malfunctions of the communication device according to the invention, due to a malfunction of one of the monitoring modules. Indeed, the monitoring modules contain measurement means, calculation electronics, memory, etc. The measurement electronics can be connected to external sensors, passive or active, and directly exposed to a hostile environment, for example near high voltage cables, high intensity electromagnetic radiation, etc. For functional reasons, in most cases, the measurement electronics monitoring these external sensors can not be protected against potential voltage or current spikes that may be present on the sensors. These high-intensity disturbances make the electronics of measure susceptible to frequent breakdowns. The complexity of the electronics of the calculation and communication modules contributes to the decrease in the reliability of the monitoring modules. The absence of an answer or a wrong answer are detected by the central unit. However, in case of non-response of the monitoring module or in the event of a short-circuit of the latter, the communication with the following modules stops at this point. The switching module avoids such a malfunction.

In a preferred exemplary embodiment, the switching module associated with a monitoring module may comprise a controllable timer, triggered when the monitoring module receives an electric current, and intended to deliver a signal, called the end signal, at the end of a predetermined duration. When the duration counted by the timer reaches the predetermined duration, the short-circuit means associated with the monitoring module are controlled in the closed position, either directly by the timer through the end signal, or by a control element following the reception by the latter of the end signal from the timer.

Advantageously, the controllable timer can be reset at the request of the monitoring module. Such a reset can be performed by a signal received from said monitoring module. In this case, the switching module is connected / connected, directly or indirectly, to the monitoring module and receives from said monitoring module a signal, said reset, the timer. This reset signal can be received directly by the timer, or by a control element of the switching module.

In the case where the monitoring module comprises several monitoring blocks, each arranged to measure / monitor a given parameter, the switching module may include a timer common to all the monitoring blocks. Such a common timer can be reset by each of the monitoring blocks independently of the other monitoring blocks. Alternatively, when the monitoring module comprises several monitoring blocks, each arranged to measure / monitor a given parameter, the switching module may comprise a dedicated timer associated with each of the monitoring blocks. In that case :

- each timer can perform a count of a duration equal to or different from the time counted by at least one other timer; and

- Each monitoring block can reset the timer dedicated / associated independently of others.

In this case, the switching module only switches the short-circuit means to the closed position when all the timers have made the expected count (s).

According to an exemplary embodiment, the reset signal can be received via a decoupled pulse transmitter connected / connected on the one hand to the monitoring module and on the other hand to the switching module.

In addition, according to a nonlimiting exemplary embodiment, the switching module can be made by CMOS logic components or by discrete field effect transistors, which consume little or no current.

According to another aspect of the invention, there is provided a detection system comprising:

a plurality of monitoring modules, and

a device for interrogating said monitoring modules according to the invention, each of said monitoring modules being connected to the communication wire of said device.

The monitoring modules may comprise one or more sensors for detecting leaks of liquid or gas, one or more sensors for pressure, temperature, flame, smoke, ionization, radio wave presence, pH, brightness, color, contact, presence, measurement of electrical or magnetic variables, etc. ... In one embodiment, the short-circuit means (s) associated with a monitoring module can be integrated into the monitoring module.

Each monitoring module advantageously comprises means, for example one or more resistive loads, for carrying out information transmission by current coding, said coding being a binary coding with two current values, or a coding with a plurality of values of the current. current, or else a coding to a plurality of analog values. Each current value is obtained by connecting or disconnecting a resistive resistance or a predetermined resistive load, thereby modifying the total resistance seen by the electric generator, and therefore the current delivered by it.

Description of the Figures and Embodiments

Other advantages and characteristics will appear on examining the detailed description of non-limitative examples, and the appended drawings in which:

FIG. 1 is a schematic representation of a first example of a system implementing a first example of a communication device according to the invention;

FIG. 2 is a schematic representation of a second example of a system implementing a second example of a communication device according to the invention;

FIG. 3 is a schematic representation of a third example of a system implementing a third example of a communication device according to the invention;

FIG. 4 is a partial schematic representation of another example of a communication device according to the invention, at the level of a monitoring module, in which the short-circuit means are arranged in a short-circuit module; independent circuit of the monitoring module;

FIG. 5 is a partial schematic representation of another example of a communication device according to the invention, at a monitoring module, in which the monitoring module comprises several measurement blocks; FIGURE 6 is a partial schematic representation of another example of a communication device, at a monitoring module, in which the monitoring device comprises a switching module;

FIGURE 7 is a schematic representation of the example of FIGURE 5 with a switch module;

FIGURE 8 is a partial schematic representation of another example of a communication device, at a monitoring module, and including an anti-collision module; and

FIGURE 9 is a partial schematic representation of the example of the device of FIGURE 8 further comprising a switch module.

It is understood that the embodiments which will be described in the following are in no way limiting. It will be possible, in particular, to imagine variants of the invention comprising only a selection of characteristics described subsequently isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the art. This selection comprises at least one feature preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

In particular, all the variants and all the embodiments described are combinable with each other if nothing stands in the way of this combination at the technical level.

In the figures, the elements common to several figures retain the same reference. FIG. 1 is a schematic representation of a first example of a system implementing a first example of a communication device according to the invention.

System 100 includes a communication device 102 for communicating with a plurality of 104i-104 _n monitoring modules.

The communication device 102 comprises a central unit 106 and an electrical wire 108, said communication, connecting the central unit 106 to each of the monitoring modules 104 so that the monitoring modules 104 are connected to the serial communication wire.

The central unit 106 comprises an electrical generator, and in particular a voltage generator 110, at the terminals of which the electric voltage VI is constant, and delivering a current II whose value depends on the resistance seen and is limited to a maximum value. it _my x- a law the terminal, said positive terminal of the voltage generator 110 is at a greater electrical potential, said positive potential and the other terminal 110 _2, said ground terminal, the voltage generator 110 is a smaller electric potential, said potential of mass or electric mass. The communication wire is connected to the positive terminal 10i and the ground terminal 110 ₂ is connected to the ground, in particular to the ground 112.

The central processing unit 106 further comprises one or more current receivers 114i-114 _n, connected in series to the positive terminal of the law voltage generator 110, and provided to measure the value of current emitted by the voltage generator 110.

The central unit 106 further comprises a switch 116, arranged on the positive terminal 1 10 of the voltage generator 110, between the generator 110 and the receivers 114, controllable between a non-conducting position "OFF" in which the current emitted by the voltage generator 110 does not go to the receivers 114 and an ON position in which the current emitted by the voltage generator 110 passes to the receivers 114 and then to the communication wire 108.

The communication device 102 further comprises an optional terminating load T, which corresponds to a resistor or an active load, connected on the one hand to the communication wire 108 downstream of the last surveillance module 104 _n , and on the other hand go to the land. Each monitoring module 104 is on the one hand connected to the communication wire 108 and on the other hand connected to the ground 112.

The communication device 102 further comprises, for each monitoring module 104, short-circuit means movable between:

An open position in which the current delivered by said voltage generator does not pass on said communication wire downstream of said monitoring module and is consumed by said monitoring module, and

^■ a closed position in which the current supplied by said voltage generator passes over said downstream communication over said monitoring module so that said control module does not consume current supplied by said voltage generator consumes a current or quasi nothing ;

so that each monitoring module 104, is connected to said communication wire 108, and therefore to said central unit 106, in turn and only one monitoring module is connected to the central unit at a time .

For the module i, the short-circuit means comprise two switches 118, 120 and two diodes 122 and 124. The diodes 122 and 124 are mounted head to tail on the communication wire 108. An electrical wire, referred to as the link, connects the monitoring module 104 to the communication wire 108 between the diodes 122 and 124, so that the diode 122, said upstream diode, is upstream of the communication module 104, that is to say on the side of the central unit 106, and the diode 124, called downstream, downstream of the monitoring module 104 ,. In embodiment 100 of FIGURE 1, diode 122 is optional. The switch 118 connects the connecting wire 126 to the communication wire 108 upstream of the upstream diode 122, and the switch 120 connects the connecting wire 126 to the communication wire 108 downstream of the diode. of the communication device 102 and the detection system 100 is as follows. On closing switch 112, voltage generator 110 sends an electric current which passes through receiver (s) 114. In the initial state, the switches 118, and 120, of each monitoring module 104, are open. At the first monitoring module 104i, the upstream diode 122i, optional in this embodiment, passes the current. The current then passes through the connecting wire 126i and supplies the monitoring module 104i. The downstream diode 120i blocks the flow of current to the next monitoring module. The monitoring module 104i starts to consume a nominal current of value greater than 3 mA, preferably 1 mA, and more particularly between 3 mA, preferably 1 mA, and 50 mA, measured by the receiver or receivers 114. This indicates to the central unit 106 that the first monitoring module is well connected communication wire. The module 104i performs the tasks programmed in advance and returns the information in the form of modulation of the current consumed. The modulation may be a binary modulation (0-1) such that the consumption of the module 104i oscillates between 2 values: value 1, for example 4 mA corresponding to a level 0 and value 2, for example 10 mA, corresponding to a level 1. To obtain the value 1 the monitoring module 104i connects, to the wire 126i and therefore to the communication wire 108, a first active load (not shown in FIGURE 1), and to obtain the value 1 the module of monitoring 104i (connects to the wire 126i and therefore to the communication wire 108) a second active load of different value than the first active load. The connection of a load modifies the value of the current delivered by the voltage generator 110 as a function of the value of this load. The value of the current II passing through the receivers 114 therefore varies according to the load. The receiver or receivers measure the variations in the value of the current Il which passes through them and supplies at their output a binary digital frame.

Alternatively, instead of a binary coding (0 or 1), the monitoring module can encode a plurality of current values, for example 4, 8, 12, 16, etc. each corresponding to a value or a range of predetermined current value, or analog values, to improve the functionality or the speed of transmission of the bus.

When the module 104i has completed the transmission of information to the central unit 106, it goes into a standby state in which its power consumption is zero (or almost zero), for example less than or equal to 2mA, and preferably 1mA. The switches 118i and 120i close automatically or are closed by the monitoring module before it goes into standby. The current II supplied can then cross these switches 118i and 120 ,, and supply the next monitoring module 104.

The operation, which has been described in the previous paragraph for the 104i monitoring module is then repeated for the next 104 module, and each monitoring module 104, in turn until the last 104 _n monitoring module .

During the communication cycle, the current sink (s) 114 of the central unit 106 also measure the accumulated standby current of the modules in order to improve the accuracy of the measurement of the current coded by each module.

When the last module 104 _n has completed the transmission of the information to the central unit 106, then is put on standby, and the switches 118 _n and 120 _n are closed, the current delivered by the voltage generator 110 passes through the termination means T, which can be for example a short circuit. The value of the current II delivered by the voltage generator 110 changes. This change in value is measured by the receiver or receivers 114, which detect the end of the communication cycle with the set of monitoring modules 104.

After detecting the end of a communication cycle, the switch 116 opens, thereby cutting off the power supply, and more particularly the electric current, supplied by the voltage generator 110. Each of the monitoring modules 104 returns to zero and the switches 118 and 120 of each monitoring module 104 open. The device 102 is then ready for a new communication cycle.

The voltage generator 110 is arranged to deliver a current and / or voltage such that it takes into account the resistance represented by the total length of the communication wire 108. In this case, each monitoring module 104, or the means of short circuit associated with a monitoring module 104 ,, may comprise an electric regulator (not shown) configured to absorb / eliminate the excess voltage or current, emitted by the voltage generator 110, and corresponding to the length of the wire communication 108 downstream of the monitoring module 104, relative to the electric generator 110.

In a simplified version of the embodiment shown in FIG. 1, the optional upstream diode 122 of each monitoring module 104 may be omitted. The downstream diode 124 of each monitoring module 104 may be replaced by a first switch, such as the switch 118 or the switch 120, arranged at the same location as this downstream diode, and the switches 118 and 120 of each monitoring module can be replaced by a single switch, said second switch, disposed on the connecting wire 126. In this simplified version, when the monitoring module carries out an information transmission cycle, then the first switch is open and the second switch is closed. When the monitoring module has finished an information transmission cycle, then the first switch is closed and the second switch is open.

FIG. 2 is a schematic representation of a second example of a system implementing a second example of a communication device according to the invention.

The detection system 200, respectively the communication device 202 of the detection system 200, shown in FIG. 2 comprises all the elements of the detection system 100, respectively of the communication device 102 of the detection system 100, represented in FIG. 1 except that the CPU 106 comprises a single receiver 114 and the communication device 102 does not include T-terminating means.

The communication device 202 further comprises a second central unit 206 connected to the communication wire at its downstream end seen from the side of the central unit 106. The central unit 206 comprises a voltage generator 210, at the terminals of which the voltage electrical V2 is constant, and delivering a current 12 whose value depends on the resistance seen by the voltage generator 210 and is limited to a maximum value I2 _max . The current 12, supplied by the voltage generator 210 of the central unit 206, is transmitted on the communication wire 108 in the direction opposite to the direction of emission of the current II supplied by the voltage generator 110 of the central unit 106.

A terminal 210i, called the positive terminal, of the voltage generator 210 is at a larger electrical potential, called the positive potential, and the other terminal 210 ₂ , called the ground terminal, of the voltage generator 210 is at a smaller electric potential. , said potential of mass or electric mass. The communication wire 108 is connected to the positive terminal 210i and the ground terminal 210 ₂ is connected to ground, in particular to the ground 112.

The central unit 206 further comprises a switch 216, disposed on the positive terminal 210i of the voltage generator 110, between the generator 210 and the receiver 214, controllable between a non-conducting position "OFF" in which the current emitted by the voltage generator 210 does not pass to the receiver 214 and an ON position in which the current emitted by the voltage generator 210 passes to the receiver 114 and then to the communication wire 108.

In addition, each central unit 106, 206 comprises a detector means, respectively 218, 220 for detecting the end of a communication cycle carried out by the other central unit. The detector means 218, 220 of a central unit 106, 206 constitutes or comprises a terminating means enabling the other central unit to detect the end of a communication cycle.

Finally, the communication device 202 comprises an optional synchronization wire 222 for synchronizing the two central units 106 and 206.

The operation of the communication device 202 and the detection system 200 is as follows. A communication cycle is initiated and carried out by the central unit 106 in the direction of propagation of the current II. The communication cycle performed by the central unit 106 starts with the monitoring module 104i and ends with the monitoring module 104 _n . The central unit 106 detects the end of the communication cycle thanks to the detector means 220 and the switch 112 disconnects the power supply of the monitoring modules 104 by the voltage generator 110. The central unit 206 detects the current sent by the central unit 106 and the end of the communication cycle carried out by the central unit 106 by means of the detector 220 and initiates and then realizes in turn a communication cycle by feeding each in turn the monitoring modules 104 in the direction of the current 12. The communication cycle performed by the CPU 206 begins with the monitoring module 104 _n and ends with the monitoring module 104i. The communication cycle is carried out in the same manner until the electric current supplied by the central unit 206 reaches the central unit 106, and in particular the detector 218. The surveillance modules 104 are perfectly symmetrical of their communication interface, their operation is transparent for the two central units 106 and 206.

The central unit 206 detects the end of the communication cycle thanks to the detector means 218 and the switch 212 disconnects the power supply of the monitoring modules 104 by the voltage generator 210. The central unit 106 detects the current sent by the central unit 206 and the end of the communication cycle performed by the central unit 206 with the aid of the detector 220 and then in turn carries out a new communication cycle.

The synchronization of the two central units can be performed by the synchronization wire 222.

This so-called redundant embodiment makes it possible to monitor all the monitoring modules in the event of the communication wire 108 being cut or short-circuited, or in the event of failure of a central unit.

Optionally, the idle central unit, when it detects the current sent by the active central unit, can code with the terminations 218 and 220 a specific current coding allowing the active central unit to recognize the presence a central unit in standby, and thus complete its communication cycle. The terminations are switchable in this case. FIGURE 3 is a schematic representation of a third example of a system implementing a third example of a communication device according to the invention.

The detection system 300, respectively the communication device 302 of the detection system 300, shown in FIG. 3 comprises all the elements of the detection system 100, respectively of the communication device 102 of the detection system 100, shown in FIG. except that the CPU 106 comprises a single receiver 114 and the communication device 102 does not include T-terminating means.

In the device 302 of FIG. 3, the two ends of the communication wire are connected to the central unit 106. The central unit 106 comprises a selection means 304, which in the example shown is a switch for selecting the end of the communication wire on which is sent the current supplied by the voltage generator 110. This selection means 304 connects the positive terminal 110i of the voltage generator 110:

at one end 108i of the communication wire 108 in a first position PI, and

at the other end 108 ₂ of the communication wire 108 in a second position P2.

Thus, when the selection means 304 is in its position P1, it is the monitoring module 104i which first receives the current delivered by the voltage generator 110: this direction of emission of the current will be called the "direct" direction in the following. When the selection means 304 is in position P2 is the monitoring module 104 _n which receives the first current output by the voltage generator 110: the sense current of emission shall be called the direction "reverse" in after.

In addition, the central unit 106 comprises a first detector means 318 for detecting the end of a communication cycle carried out in the opposite direction and a second detector means 320 for detecting the end of a communication cycle carried out in the direct sense. In the loop version, the means 318 and 320 may be replaced by a single termination connected between the elements 114 and 304. The operation of the communication device 302 and the detection system 300 is as follows. The selection means 304 is in the position P1. A communication cycle is initiated and realized, by the central unit 106, in the forward direction of propagation of the current I. The communication cycle carried out in the forward direction starts with the monitoring module 104i and ends with the monitoring module 104 _n . The central unit 106 detects the end of the communication cycle carried out in the forward direction by the detector means 318. Then the switch 304 changes position and goes from the position PI to the position P2, either automatically or in a manner controlled by the central unit for example or an electronic supervision module (not shown) of the central unit.

A new communication cycle is initiated and realized, by the central unit 106, in the opposite direction of propagation of the current I. The communication cycle, carried out in the opposite direction, starts with the monitoring module 104 _n and ends with the monitoring module 104i. The central unit 106 detects the end of the communication cycle carried out in the forward direction by the detector means 320. Then, the switch 304 changes its position and goes from the position P2 to the position P1. The device 302 is ready to carry out a new communication cycle in the forward direction, and so on.

This embodiment, said in a loop, allows the monitoring of all the monitoring modules in case of interruption or short circuit of the communication wire 108, with a single central unit 106.

In this embodiment, it is possible to suppress the switch 116 and to use a selection means 304 at three positions:

a position PI connecting the end 108i of the communication wire

108 to the voltage generator 110,

a position P2 connecting the end 108 ₂ of the communication wire 108 to the voltage generator 110, and a position P3 no longer connecting the communication wire 108 voltage generator 110.

In all the examples described with reference to FIGURES 1-3, the short-circuit means are integrated in the monitoring module.

Of course, the short circuit means associated with a monitoring module may not be integrated into the monitoring module.

Similarly, the means for detecting the end of a communication cycle may not be integrated in the central units.

In addition, the short-circuit means associated with a monitoring module can, in the closed position, completely short-circuit, in particular completely disconnect from the communication wire, the monitoring module, instead of the monitoring module being set up. Standby.

In addition, the switches 118 and 120 may be replaced by a single switch connected between the anodes of the diodes 122 and 124.

FIGURE 4 is a partial schematic representation of another example of a device according to the invention that may be used in each of the systems of FIGURES 1-3.

As shown in FIG. 4, the short-circuit means are arranged in a short-circuit module 402, independent of the monitoring module 104. The short-circuit module 402, shown in FIG. switches 118, 120 and diodes 122 and 124 as shown in FIGURES 1-3.

The short-circuit module 402 further comprises a switch 404, connected on the one hand to the communication wire 108 between the diodes 122 and 124 and on the other hand between the switches 118 and 120.

The short-circuit module 402 is connected to the monitoring module 104 via the switch 404. In some cases, an optional load 406 may be arranged between the switch 404 and the monitoring module 104. When the monitoring module 104 is energized the switch 404 is closed and when the monitoring module 104 has finished communicating, the switch 404 opens to shorten the monitoring module 104.

The difference between the embodiment shown in FIGURE 4 and that shown in FIGURES 1-3 is that in FIGURES 1-3, when the monitoring module has finished communicating, it goes into sleep mode and consumes more power while in the case of FIGURE 4, the monitoring module 104 is further short-circuited and is not connected at all to the communication wire 108.

As shown in FIG. 4, the monitoring module comprises a block 408 for measuring / monitoring a predetermined parameter.

FIGURE 5 is a partial schematic representation of another example of a device according to the invention that can be used in each of the systems of FIGURES 1-3.

In the example shown in FIGURE 5, the monitoring module 104 includes a plurality of blocks measuring / monitoring 408i-408 _m of a same predetermined parameter or a plurality of predetermined parameters. Optionally each 408i-408 _m monitoring block is dedicated to measuring / monitoring a given parameter. Thus, the monitoring module 104 makes it possible to measure / monitor m parameters.

Short-circuit module 402 includes switches 118, 120 and diodes 120-122. In addition, for each measurement block 408, the short-circuit module 402 includes a switch 404 for connecting or short-circuiting the measurement block 408 as described with reference to FIGURE 4. In addition, for some measurement blocks 408, an optional load 406 may be arranged between the switch 404 and the measurement block 408 so as to adapt the voltage supplied to this measurement block 408.

Alternatively, the short-circuit module 402 can be integrated in the monitoring module 104.

Alternatively, the monitoring module 104 may be connected to the communication wire according to the examples shown in FIGURES 1-3. In other words, the short-circuit means can be integrated into the monitoring module 104, and may not include switch 404. In this case, each measurement block 408 will go to sleep when it has finished its communication.

FIGURE 6 is a partial schematic representation of another example of a communication device at a monitoring module, wherein the monitoring device comprises a switching module.

The monitoring device shown in FIGURE 6 includes all the elements of the device shown in FIGURE 4.

It further comprises a switching module 602 for switching the positions of the switches 118, 102 and 404 in the closed position. The switching module 602 is connected on the one hand to the communication wire 108 between the diodes 122 and 124 and on the other hand between the switches 118 and 120.

The switching module 602 includes a timer 604 for counting a predetermined time from the moment the monitoring module 104 receives a power signal from the communication wire 108.

In addition, the monitoring module 104 includes a means 606, such as a decoupled electric pulse transmitter in the form of a capacitor, for setting the timer 604 to zero so as to restart the countdown.

The operation of the switching module 602 is as follows. As soon as it detects a supply voltage on the communication wire 108 it:

- switches the switch 404 to the closed position and the switches 118 and 120 in the open position to provide power to the monitoring module 104; and

- triggers the timer 604 to perform the count.

When the timer 604 completes a countdown and transmits an end of countdown signal, the switch module 602 switches the switch 404 to the open position and the switches 118 and 120 in the closed position to short-circuit the monitoring module 104.

At any time during the countdown, and before the end of the count, performed by the timer 604 the monitoring module 104 can restart, that is to say, reset the count, performed by the timer to delay the short- circuit.

The switching module 602 can be implemented with an enhancement field effect transistor whose threshold voltage is greater than or equal to the minimum supply voltage. Other well-known electronic elements can be substituted for this field effect transistor, for example a switch with a sufficient series resistance, a bipolar transistor or a depletion field effect transistor biased so as to obtain the desired value of the supply voltage.

The switching module 602 makes it possible to prevent malfunctions of the communication device according to the invention when the monitoring module 104 is defective. Indeed, when the monitoring module 104 is defective and does not respond, it will in any case be short-circuited by the switching module 602 after the time counted by the timer and the communication will continue to the next monitoring module.

The example given in FIGURE 6 is based on the embodiment of FIGURE 4. Of course, it can also be implemented for the embodiments described with reference to FIGURES 1-3.

In addition, the switching module can be integrated in the short-circuit module 402, or in the monitoring module 104.

Alternatively, all the modules 402, 602 and 104 can be integrated into a single module.

FIGURE 7 is a schematic representation of the example of the

FIGURE 5 with a switching module.

The device of FIGURE 7 comprises all the elements of the device of FIGURE 5. The device of FIGURE 7 further comprises a switching module 602 provided with a timer 604. In addition, in the monitoring module 104 a reset means 606, the timer 604 is associated with each measurement / monitoring block 408 ,. thus, each measurement / monitoring block 408 can zero the count realized by the timer 604 independently of the other measurement / monitoring blocks.

Alternatively, one and only one reset means 606 common to all measurement / monitoring blocks can be used.

Alternatively, the switching block 602 may comprise a timer dedicated to each of the measurement / monitoring blocks 408,.

The example given in FIGURE 7 is based on the embodiment of FIGURE 5. Of course, it can also be implemented for the embodiments described with reference to FIGURES 1-3 in the case where the monitoring module includes several measurement / monitoring blocks.

In addition, the switching module 602 can be integrated in the short-circuit module 402, or in the monitoring module 104.

FIG. 8 is a partial schematic representation of another example of a communication device, at the level of a monitoring module, and comprising an anti-collision module that can be used in the redundant version or the loop version of the device according to FIG. invention, such as for example the non-limiting embodiments described with reference to FIGURES 3 and 4.

The device shown in FIGURE 8 comprises a monitoring module 104 comprising a single measurement / monitoring block 408.

The device further comprises a short-circuit module 402. The short-circuit module comprises the diodes 122 and 124 and the switches 118 and 120. The short-circuit module 402 further comprises a third switch 802 connected to the communication 108 upstream of the short-circuit module 402, that is to say upstream of the switch 118 and the diode 122. An optional load 804 can be connected to the switch 802. upstream of the switch 802 to perform a voltage adaptation to be provided to the monitoring module 104. The short-circuit module 402 further comprises a fourth switch 806 connected to the communication wire 108 downstream of the short-circuit module 402 that is, downstream from the switch 118 and the diode 122. An optional load 808 may be connected to the switch 806 downstream of the switch 806 to provide a voltage adaptation which will be supplied to the monitoring module 104.

The device shown in FIGURE 8 further comprises an anti-collision module 810 whose function is to monitor the communication wire 108 upstream and downstream of the short-circuit device 402, and therefore of the monitoring module 104, to detect the presence communication signal from both directions and report this collision.

The collision avoidance module 810 includes an "AND" logic element, including:

one of the inputs is connected to the switch 802, possibly via the load 804, to detect the presence of a signal supplied by a central unit downstream of the short-circuit module 402;

the other of the inputs is connected to the switch 806, possibly via the load 808, to detect the presence of a signal supplied by a central unit downstream of the short-circuit module; and

the output is connected to a collision signaling module 814. The collision avoidance module 810 also includes charges 816 and

818 to report a collision by connecting them to received signals.

Finally, diodes 820 and 822 are respectively connected to the switches 802 and 806, possibly via the loads 804 and 808 to prevent a signal received upstream of the short-circuit module 402 on the communication wire passes to the downstream of the short-circuit module 402 on the communication wire, and vice versa.

When a signal is provided on the communication wire 108 from the upstream of the short-circuit module 402, and therefore from the upstream of the module monitoring 104, this signal is detected by the logic element 812 via the switch 802, possibly via the load 804. If at the same time a signal is provided on the communication wire 108 since the downstream of the short-circuit module 402, and therefore from the downstream of the monitoring module 104, this signal is detected by the logic element 812 via the switch 806, possibly via the load 808 In this case, the logic element "AND" 812 provides a collision detection signal to the collision signaling module 814. The collision signaling module 814 connects the load 816, respectively 818, to the switch 802 (optionally through the load 804), respectively to the switch 806 (possibly via the load 804) to signal the collision upstream or downstream of the short-circuit module 402, ie the module of surv 104.

In the example given in FIG. 8, the collision avoidance module is in the form of a separate module. Of course, the collision avoidance module 810 can be integrated in the short-circuit module 402, or in the monitoring module 104.

Alternatively, all the modules 402, 810 and 104 can be integrated in a single module.

In addition, in the example given in FIGURE 8, the monitoring module comprises only a single measurement / monitoring block. Of course, the monitoring module may comprise a plurality of measurement / monitoring blocks, as shown in FIGURES 5 and 7.

The invention also relates to a communication device comprising both an anti-collision module and a switching module. FIG. 9 gives a partial schematic representation of a communication device at a monitoring module, said device comprising both a switching module and an anti-collision module.

The example shown in FIG. 9 includes all the elements of the example shown in FIG. 8 and the switching module 602 described with reference to FIGURES 6 and 7. In the example shown in FIG. 9, the monitoring module comprises only a single measurement / monitoring block. Of course, the monitoring module may comprise a plurality of measurement / monitoring blocks, as shown in FIGURES 5 and 7.

In the example shown in FIGURE 9 the short-circuit module

402, the collision avoidance module 810, the switching module 602 and the monitoring module 104 are shown separately. Of course, at least two of these modules, in particular all the modules, can be integrated in the same module.

Naturally, the invention is not limited to the examples which have just been described. For example, in the examples given the electric generator is a voltage generator. Of course, it may be a current generator or a combination of a voltage generator with a current generator.

Claims

A current coding communication device (102; 202; 302) with a plurality of so-called monitoring modules (104) arranged in an environment to be monitored, said device (102; 202; 302) comprising:

a unit (106,206), called a central unit, comprising:

^■ an electrical generator (110,210), and

^■ at least one means (114,214), said receiver, for measuring the current supplied by said electric generator (110,210); at least one electrical wire (108), called a communication wire, intended to connect said central unit (106, 206) to each of said monitoring modules (104) and to transport, to each of said monitoring modules (104), the current delivered by said electric generator (110,210); and

- for each monitoring module (104), at least one means

(118-124), called short-circuit, movable between:

^■ an open position in which the current delivered by said electrical generator (110,210) does not pass over said communication line (108) downstream of said monitoring module (104) and is drawn by said monitoring module (104), and

^■ a closed position in which the current delivered by said electrical generator (110,210) passes over said communication line (108) downstream of said monitoring module (104) so that said monitoring module (104) does not consume, or almost not, the current delivered by said electric generator (110,210);

so that each monitoring module (104) is connected to said communication wire (108) in turn.

2. Device (102; 202; 302) according to claim 1, characterized in that it further comprises a control means (116,216) of start and / or end transmitting a variable current on the communication wire (108) by the electric generator (110, 210).

3. Device according to any one of the preceding claims, characterized in that it comprises a second electrical wire, said ground wire, provided for connecting said central unit (106,206) to each of the monitoring modules (104), the wire communication device (108) being connected to a terminal of the central unit (106,206) set at a larger electrical potential, said positive potential, and the ground wire being connected to a terminal of the central unit (106,206) set to a smaller electric potential, called electrical ground.

4. Device (102) according to any one of the preceding claims, characterized in that it comprises at least one means (T), said termination, connected to the distal end of the communication wire (108) relative to the central unit (106) and provided for detecting the end of a communication cycle.

5. Device (202) according to any one of the preceding claims, characterized in that it comprises two central units (106,206), each connected to one end of the communication wire (108).

6. Device (202) according to the preceding claim, characterized in that at least one, preferably each, central unit (106,206) comprises at least one detection means (218,220) for the end of emission of a current emitted on the communication wire (108) by the electrical generator (210, 110) of the other unit (206, 106).

7. Device (202) according to claim 4 and any one of claims 5 or 6, characterized in that it comprises a termination means associated with each central unit (106,206), on the side of the other central unit ( 206, 106), in particular integrated in the detection means (220, 218) of the other central unit (206, 106).

8. Device (202) according to any one of claims 5 to 7, characterized in that it further comprises a synchronization means (222) of the two central units (106,206) between them.

9. Device (302) according to any one of claims 1 to 4, characterized in that the communication wire (108) is connected to the central unit (106) at its two ends (108i, 108 ₂ ) said device further comprising at least one selection means (304), such as a switch, of a current-sending direction provided by said central unit (106) on said communication wire (108) in a sense or in the other.

10. Device (302) according to claim 9, characterized in that it comprises:

for at least one, preferably each, direction of emission of the current on the communication wire (108), at least one means of detection (318, 320) of end of current emission in said direction, and / or

a termination means associated with each direction of current emission in the communication wire (108), disposed on the side of the distal end of said communication wire in said transmission direction, in particular integrated in the detection means; associated with said direction of emission.

11. Device (202, 302) according to any one of claims 5 to 10, characterized in that it further comprises, for at least one monitoring module, at least one means (810), said anticollision, to detect an emission simultaneous on the communication wire:

a current supplied from the upstream of said monitoring module, and

a current supplied from the downstream of said monitoring module.

12. Device (102,202,302) according to any one of the preceding claims, characterized in that it further comprises, for at least one monitoring module, at least one means (602), said switching, for control / switch the short circuit means associated with said monitoring module.

13. Device (102; 202; 302) according to any one of the preceding claims, characterized in that at least one receiver (114,214) comprises at least one ammeter.

A detection system (100; 200; 300) comprising:

- a plurality of monitoring modules (104i-104 _n), and - a communication device (102; 202; 302) with said monitoring modules (104i-104 _n) according to any one of the preceding claims, each of said modules monitoring (104i-104 _n) being connected to the communication line (108) of said device (102; 202; 302).

15. System (100; 200; 300) according to the preceding claim, characterized in that each monitoring module (104i-104 _n ) comprises means for carrying out information transmission by current coding, said coding being a binary coding with two current values, or a coding with a plurality of current values, or a coding with a plurality of analog values.