Communication method for sensor with memory

Abstract

The invention relates to a communication method for a control system having a sensor comprising an analog element and a digital element. The communication method comprises: a step of transmitting an analog signal within a first time period (T1); a step of receiving a response; a step of sending a digital interrogation signal to the digital element for a third time period (T3); and a step of receiving a digital response signal from the digital element for a fourth time period (T4). The analog signal varies within a voltage range between a lower limit and an upper limit; the digital interrogation signal has a high interrogation voltage, the digital response signal has a high response voltage, and the high interrogation voltage and the high response voltage are higher than an upper limit of the analog signal.

Description

Technical Field

[0001] The present invention relates to a signal communication and power supply method, which is particularly applicable to an aviation environment, and more specifically, to an aircraft. Background Art

[0002] Controlling an aircraft requires the use of a large number of sensors and measuring probes to continuously monitor parameters that are crucial for the proper functioning of the aircraft.

[0003] Some of these sensors and probes must be deployed in environments that are difficult to access and / or have significant operating constraints.

[0004] An example of such an environment is an aircraft fuel tank, which is an enclosed space requiring significant protection, with limited access and wiring.

[0005] Furthermore, the interior of the tank contains fuel in vapor form, thus creating an explosive atmosphere with all the associated risks. This explosive atmosphere severely limits the available current and power, and prohibits the use of complex electronic components that could generate heat and / or sparks.

[0006] Therefore, a single-wire connection interface is preferred to power passive analog sensors and acquire their response to the power stimulus over a single cable. In the case of sensors located within a fuel tank, such as fuel level sensors or densitometers, these sensors are capacitive and operate by transmitting an excitation voltage and measuring an analog response.

[0007] Furthermore, it is desirable to obtain sensor-specific data, such as sensor-specific calibration data, to improve measurement accuracy. Such data is preferably stored directly inside the sensor and accessed via the same connector as the measurement.

[0008] This ensures that data is directly associated with the specific sensor it relies on, without any confusion, and can be re-accessed at any time if needed (e.g. after a sensor control system restart).

[0009] However, this data is stored digitally in electronic component-type memories, which can interfere with traditional analog communications. Summary of the Invention

[0010] The object of the present invention is to overcome the above-mentioned drawbacks and to propose a communication method that allows interrogation of data stored in electronic components and communication with sensors or actuators operating in an analog manner.

[0011] To this end, the present invention relates to a method for communication between a control system and a sensor, the sensor comprising both analog and digital components. Furthermore, the control system is connected to the sensor via a single cable, in particular comprising a central core and a peripheral shield. More specifically, the communication method comprises at least:

[0012] - a simulation signal sending step, during which the control system sends a simulation signal during a first period of time;

[0013] - a response receiving step, during which the control system receives a response from the simulation element;

[0014] - a digital interrogation signal sending step, during which the control system sends a digital interrogation signal to the digital element during a third period of time;

[0015] - a digital response signal receiving step, during which the control system receives a digital response signal from the digital component during a fourth period of time.

[0016] According to the present invention:

[0017] - the analog signal varies within a voltage range between a lower limit and an upper limit;

[0018] - the digital interrogation signal has a high interrogation voltage;

[0019] - the digital response signal has a high response voltage;

[0020] The high interrogation voltage and the high response voltage are both higher than the upper limit of the analog signal.

[0021] This communication method enables the simultaneous transmission of analog excitation, DC supply voltage, and digital data from digital components over a single cable or wire. Reducing the number of wires or cables results in savings in weight, number of connection points, and protective components. Furthermore, the data stored in the digital components can improve the processing of the analog signals provided by the analog components.

[0022] In particular, the response of the analog component is provided via a specific analog communication line.

[0023] In addition, the load voltage of the digital component must be outside the analog signal voltage. Furthermore, the load voltage of the digital component can be a DC voltage.

[0024] The communication method may include at least one voltage sending step during which the control system sends the load voltage to the digital component during the second period.

[0025] The first time period, the second time period, the third time period and the fourth time period may be different and performed in a predetermined order.

[0026] The high interrogation voltage may be equal to the high response voltage and / or the load voltage.This feature ensures that digital devices do not interfere with analog signals.

[0027] Furthermore, the load voltage may be greater than an upper limit of the analog signal.

[0028] The digital interrogation signal may have a zero low interrogation voltage, and / or the digital response signal may have a non-zero low response voltage.

[0029] The low voltage of the digital response signal can be strictly greater than the upper limit of the analog voltage. This feature allows the response of the digital component to be transmitted through the component that isolates the analog component from the digital component.

[0030] The digital element may be an electrically erasable programmable read-only memory. This feature allows sensor-related data to be stored directly within the sensor, maintaining a direct association between the data and the specific sensor, and can be periodically re-read directly by the control system.

[0031] The digital response signal may represent sensor-related data stored in the digital component, in particular data including calibration data of the analog component. This feature allows improving sensor measurement accuracy by compensating for individual differences in sensors caused, for example, by manufacturing tolerances.

[0032] The present invention also relates to an assembly comprising:

[0033] - control systems;

[0034] - sensors, which include analog and digital components;

[0035] - a single cable, in particular comprising a central core and an outer shield, capable of connecting the control system and the sensor;

[0036] The components are configured to implement the communication method as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be more readily understood, and other features and advantages will become more apparent, from the following detailed description of embodiments given by way of example only and with reference to the accompanying drawings, which are intended to supplement the understanding of the invention and the description of its implementation and, where appropriate, to contribute to its definition, in which:

[0038] [ Figure 1 ] is a schematic diagram of a control system, analog components and digital components for implementing the communication method according to the present invention.

[0039] [ Figure 2 ] is a graphical representation of the signals exchanged during the communication method according to the present invention. DETAILED DESCRIPTION

[0040] Figure 1 FIG. 1 is a schematic diagram of a component 1 for implementing the communication method according to the present invention.

[0041] The assembly 1 comprises at least one control system 3 and a sensor 5 , which are electrically connected to one another via a single cable 7 .

[0042] The assembly 1 is particularly suitable for being mounted on an aircraft and is configured to measure one or more parameters of the aircraft in flight.

[0043] The control system 3 may be a computer system, which includes:

[0044] - at least one processor capable of performing numerical calculations and executing computer programs, and

[0045] - at least one memory capable of storing data and instructions for implementing such a computer program.

[0046] exist Figure 1 In the diagram, the cable 7 is shown only in schematic form.

[0047] The cable 7 can be a coaxial connection line comprising a high-impedance conductive central core and a peripheral shielding layer serving as ground. More specifically, the cable 7 can pass through a wall P suitable for separating two different environments, the control system 3 being located in one environment and the sensor 5 being located in the other environment.

[0048] Sensor 5 includes:

[0049] - a simulation element 11 connected directly to the cable 7, and

[0050] A digital component 13 connected to the cable 7 via an interface 15 .

[0051] The analog component 11 is, for example, a passive analog sensor, such as a capacitive fuel level sensor or a density meter in an aircraft fuel tank.

[0052] According to the embodiment shown, the analog component 11 provides an analog input signal, also referred to as an excitation signal.

[0053] The digital component 13 comprises, for example, a memory 17, in particular an electrically erasable programmable read-only memory (abbreviated to EEPROM). The memory 17 is, for example, a 1024-bit memory.

[0054] This type of memory is a passive storage element that can store data without power supply, so the information is not lost when the component 1 is no longer powered.

[0055] Furthermore, these passive components require minimal current to access stored data and generate negligible heat.

[0056] The memory 17 has, for example, an input terminal I, an output terminal O, and a DC power supply terminal.

[0057] The digital component 13 may also include a capacitor 19 , in particular calibrated to supply DC power to the memory 17 during operation, the capacitor being connected to the DC power supply terminal of the memory 17 and powered by the cable 7 via the interface 15 .

[0058] In addition, the digital component 13 may further include a power supply diode 21, which is provided between the interface 15 and the capacitor 19, for supplying power to the memory 17 and preventing it from discharging. The power supply diode 21 is a specific but non-limiting embodiment for allowing power to be supplied to the memory 17.

[0059] The digital component may further include a switch 23, in particular, for alternately connecting the input terminal I or the output terminal O of the memory 17 to the cable 7 through the interface 15, or to the ground, thereby forming an open-drain output.

[0060] According to one particular embodiment, the capacitor 19 , the supply diode 21 and the switch 23 may be integrated and formed as an integral part of the memory 17 .

[0061] The interface 15 may comprise a control diode 25, in particular a Zener control diode 25, which is connected in parallel with the digital component 13. The control diode 25 makes it possible to limit the voltage input to the digital component 13.

[0062] According to an example embodiment, the interface 15 may further include:

[0063] - an input resistor 26 connected in series, making it possible to limit the current in the control diode 25; and

[0064] An input diode 29 , in particular a nano input diode 29 , is arranged upstream of the input resistor 26 .

[0065] The input diode 29 is oriented towards the cable 7 and serves to generate an offset voltage for the digital component 13. In practice, the digital component 13 is powered only when the input voltage is higher than the threshold voltage of the input diode 29.

[0066] The interface 15 may further comprise a blocking diode 31 , in particular a standard blocking diode 31 , which is arranged upstream of the input resistor 26 .

[0067] More specifically, the blocking diode 31 is oriented in reverse so as to block all negative voltages present in the cable 7 during analog communications.

[0068] Interface 15 may also include a first resistor 27 connected in parallel with control diode 26. First resistor 27 allows the voltage level to be forced to zero when the output of digital element 17 is grounded. In fact, without first resistor 27, the input of digital element 13 would be at a floating potential when blocking diode 31 is non-conductive due to a zero or negative input voltage.

[0069] The control system 3 is configured to communicate with the digital component 13 at a high voltage Vcc_d via the output resistor 35 because the output of the digital component 13 is an open-drain output. The output resistor 35 is only active during the exchange with the digital component 13.

[0070] Figure 2 is a graphical representation of the signals exchanged during the communication method according to the present invention. More specifically, Figure 2 The voltage V across the cable 7 is shown, measured at a point X, at different stages during the communication method according to the invention.

[0071] The point X is located between the control system 3 and the input diode 29 .

[0072] The communication method includes an analog communication phase, which includes an analog signal sending step, during which the control system 3 sends an analog signal during a first period T1 , and a response receiving step, during which the control system 3 receives a response from the analog element 11 .

[0073] The analog signal advantageously varies between a lower limit (eg, −Vcc_a) and an upper limit (eg, Vcc_a), the upper limit being the opposite of the lower limit. For example, the upper limit is selected to be lower than the threshold voltage of the input diode 29 to prevent interference from the digital element 13.

[0074] Furthermore, the analog signal may be a sinusoidal signal, for example.

[0075] Figure 2 The simulated communication phase is shown as occurring first in time, but may occur before and / or after other steps described below and may be repeated during the communication method.

[0076] The communication method also comprises a step allowing communication with the digital element 13 , which comprises in sequence a load phase, an inquiry phase and a response phase.

[0077] The load phase includes a DC voltage sending step, during which the control system 3 sends a load voltage, in particular a DC load voltage, to the digital component 13 during a second time period T2.

[0078] The load voltage is selected to be higher than the threshold voltage of the input diode 29 so as to reach the capacitor 19. The load voltage may be equal to the high voltage value Vcc_d, for example.

[0079] In particular, in the embodiment shown, the load voltage is greater than or equal to the sum of the supply voltage required by the digital component 13 and the offset voltage generated by the input diode 29 .

[0080] The interrogation phase comprises a digital interrogation signal sending step, during which the control system 3 sends a digital interrogation signal to the digital element 13 during a third time period T3.

[0081] The digital interrogation signal depends on the digital element 13, for example, a specific signal for the memory 17, which varies discontinuously between a high interrogation voltage and a low interrogation voltage. The high interrogation voltage can be selected to be higher than the threshold voltage of the input diode 29, for example, equal to Vcc_d, and the low interrogation voltage can be selected to be, for example, zero.

[0082] The response phase includes a digital response signal receiving step during which the control system 3 receives a digital response signal from the digital element 13 during a fourth time period T4.

[0083] The digital response signal is determined by digital element 13 and varies discontinuously between a high response voltage and a low response voltage. The high response voltage can be selected to be higher than the threshold voltage of input diode 29, for example, equal to Vcc_d, and the low response voltage can be selected to be non-zero, for example. The non-zero low response voltage is attributed to input resistor 26, output resistor 35, input diode 29, and blocking diode 31.

[0084] The digital response signal represents, for example, data stored in the memory 17 .

[0085] According to the present invention, the first, second, third, and fourth time periods T1, T2, T3, and T4 are different and occur sequentially in a predetermined order. This configuration enables communication with analog components 11 and digital components 13 over a single cable 7 by time division multiplexing.

[0086] Furthermore, the analog signal varies within a voltage range whose lower and upper limits are defined by the highest values ​​of the load, interrogation, and response voltages.

[0087] This voltage offset between analog and digital signals, combined with time division multiplexing, prevents the analog and digital components from interfering during communications directed thereto.

[0088] The communication method according to the invention thus allows the transmission of analog and digital signals on a single cable to control passive sensors installed in inaccessible environments and comprising digital components such as memories, without the need for additional wiring.

[0089] Of course, the present invention is not limited to the embodiments described above by way of example only. It encompasses various modifications, alternative forms and other variants that a person skilled in the art can conceive within the scope of the present invention, in particular all combinations of the above-mentioned different operating modes, which can be adopted alone or in combination.

Claims

1. A method for communication between a control system (3) and a sensor (5), the sensor comprising an analog component (11) and a digital component (13), The control system (3) is connected to the sensor (5) via a single cable (7), in particular comprising a central core and a peripheral shielding layer, and the communication method comprises at least: - a simulation signal sending step, during which the control system (3) sends a simulation signal within a first time period (T1); - a response receiving step, during which the control system (3) receives a response from the simulation element (11); - a digital interrogation signal sending step, during which the control system (3) sends a digital interrogation signal to the digital element (13) within a third time period (T3); - a digital response signal receiving step, during which the control system (3) receives a digital response signal from the digital element (13) within a fourth time period (T4); It is characterized in that - the analog signal varies within a voltage range between a lower limit and an upper limit, - the digital interrogation signal has a high interrogation voltage, - the digital response signal has a high response voltage, And wherein the high interrogation voltage and the high response voltage are higher than an upper limit of the analog signal.

2. The communication method according to claim 1, comprising at least one voltage transmission step, during which the control system (3) transmits the load voltage for the digital element (13) within a second period (T2).

3. The communication method according to claim 2, wherein: The first time period (T1), the second time period (T2), the third time period (T3) and the fourth time period (T4) are different and are performed in a predetermined order.

4. The communication method according to claim 1, wherein: The high interrogation voltage is equal to the high response voltage and / or equal to the load voltage.

5. The communication method according to any one of the preceding claims, characterized in that The load voltage is greater than an upper limit of the analog signal.

6. The communication method according to any one of the preceding claims, characterized in that The digital interrogation signal has a low interrogation voltage of zero, and / or wherein the digital response signal has a low response voltage that is non-zero.

7. The communication method according to claim 3, wherein: The low response voltage is lower than, in particular strictly lower than, the upper limit of the analog signal.

8. The communication method according to any one of the preceding claims, characterized in that The digital element (13) is an electrically erasable programmable read-only memory.

9. Communication method according to the preceding claim, characterized in that The digital response signal represents data relating to the sensor (5) stored in the digital element (13), in particular data including calibration data for the analog element (11).

10. An assembly (1) comprising: - control system (3), - a sensor (5) comprising an analog component (11) and a digital component (13), and a single cable (7), in particular comprising a central core and a peripheral shield, capable of connecting the control system (3) and the sensor (5), The component (1) is configured to implement the communication method according to any one of the preceding claims.

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