WO2001044760A1

WO2001044760A1 - Circuit and method for recording measured values

Info

Publication number: WO2001044760A1
Application number: PCT/DE1999/004011
Authority: WO
Inventors: Marten Swart; Helmuth Orlogi
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-12-16
Filing date: 1999-12-16
Publication date: 2001-06-21

Abstract

The invention relates to a circuit and method for recording measured values, in particular for the area of application in which a central evaluation device processes signals of a number of sensors. The circuit comprises an input terminal, a data terminal and a processing device, which converts input signals, which are received via the input terminal, into a form that can be transmitted via the databus. The aim of the invention is to further develop the generic circuit in such a way that the use thereof for recording measured values is simplified and improved. To this end, the processing device comprises a switching device, which adapts the behavior of the processing device to the type of input signal in such a manner that the processing device can process non-uniform input signals and can convert them into a transmittable form.

Description

description

Circuit arrangement and method for data acquisition

The present invention relates to a circuit arrangement for the measurement value acquisition with an input connection for establishing a connection to an external sensor, a data connection for establishing a connection to a data bus and with a processing device which converts input signals received via the input connection into a transmitter Data bus transmissible form converts, further a method for data acquisition.

Such circuit arrangements and methods are required in the entire measuring technology. In particular, they can be found in

Areas of application in which a central evaluation, control or regulating device processes signals from several sensors. One of the possible areas of application is automotive engineering. A large number of different sensors can be found in modern motor vehicles, for example sensors which provide information for engine control or the control of occupant protection systems.

From the international patent application WO 89/09146 a generic circuit arrangement and a method for data acquisition is known. In the known circuit arrangement, individual sensors are each assigned to a processing device, a so-called evaluation circuit. These evaluation circuits are each matched to the corresponding sensor from which they receive signals. The signals emitted by the sensors are processed by the corresponding evaluation circuits at the respective installation location of the sensors m in a manner that is compatible with a central control device and in a form suitable for transmission. The output signals processed in this way are then, if necessary still via an assigned interface, via an input provided between the circuit arrangement and the control device. Transfer wire line to the control unit. The control unit does the rest; Evaluation of the information supplied by the sensors.

The object of the present invention is to propose an improved method for measured value acquisition and to further develop the generic circuit arrangement in such a way that its use in measured value acquisition is simplified and improved.

The object is achieved in a circuit arrangement for recording measured values of the type mentioned at the outset by the characterizing features of claim 1.

Accordingly, the processing device has a switching device which adapts the behavior of the processing device to the type of input signal in such a way that the processing device can process various input signals and convert them into the transferable form.

Furthermore, the object is achieved by the method according to the invention, in which, after receiving a request signal arriving via a data connection, first a sensor located at an input connection is activated, then a measurement value supplied by the sensor is recorded, then the sensor is deactivated and the measurement value is transmitted via the data connection becomes.

The advantages achieved with the present invention are, in particular, that the circuit arrangement can be used more universally. It has proven particularly favorable that it can record and forward the measurement data from different sensor types. A correspondingly adapted circuit arrangement no longer has to be used for each sensor type. This saves maintenance and warehousing costs, because there are not many different circuit arrangements and correspondingly different ones Spare parts are kept ready. Due to the improved possible uses due to the universality of the circuit arrangement, there is an increased need. This results in higher quantities, which in turn enable more economical production of the circuit arrangement according to the invention.

The method according to the invention has the particular advantage that sensors are used in a particularly energy-saving manner. Furthermore, the method can be used to measure on request. Measurements therefore only take place if the measurement results are actually to be used. In addition, an operating mode can also be provided in which the sensor regularly carries out measurements and buffers the measurement results, which can then be queried via the data bus at any time.

In a preferred embodiment, the processing device of the circuit arrangement according to the invention comprises several different interfaces with which it can process different types of input signals originating from the external sensors. For this purpose, alternatively or in combination, a digital interface for processing a digital input signal, an analog / digital converter for processing an analog input signal, a voltage measuring device for measuring a voltage present at the input connection, a current measuring device for measuring a current present at the input connection and a resistance measuring device for Measurement of a resistance applied to the input terminal can be provided.

In a further preferred embodiment, the switching device is designed such that it adjusts the behavior of the processing device to the type of input signal as a function of a signal received at the data connection. This proves itself both in the construction of a network of several sensors, which are connected via the data bus central measured value acquisition unit are connected, as well as very advantageous for the later maintenance of such an arrangement. In the construction, the circuit arrangements used do not have to be changed mechanically or in terms of circuit technology in order to adapt them to the respective type of input signal, that is to say to a specific sensor type. Even if a sensor is exchanged for a new, different type of sensor, a software switchover or programming of the circuit arrangement via the data connection is sufficient to adapt it accordingly to the new sensor.

In practical use, the circuit arrangement according to the invention is arranged as close as possible to the sensor connected to the input connection. This is intended to avoid falsification of the input signal supplied by the sensor. By converting the input signal into a transferable form, largely interference-free transmission of the sensor signals via the data bus is guaranteed below. This arrangement entails that the sensors and the circuit arrangement according to the invention are generally arranged at distant and often inaccessible locations.

Therefore, the processing device of the circuit arrangement according to the invention particularly preferably has a control device for activating and deactivating the external sensor connected to the input connection. The sensor can thus be switched on and off from a remote location via the data bus connected to the data connection. This is particularly advantageous for sensors that have high energy requirements and are rarely queried.

In a further preferred embodiment, the circuit arrangement according to the invention comprises a voltage supply device for supplying the external sensor connected to the input connection with energy. In an expedient development of the circuit arrangement in which the data After the applied signals are transmitted by an alternating voltage or a superimposed DC voltage, the voltage supply device takes the energy from the alternating voltage or the superimposed DC voltage applied to the data connection. This simplifies the installation of the entire arrangement of sensors, circuit arrangements and data bus, since it is not necessary to lay an energy supply line for each individual sensor.

The voltage supply device particularly expediently comprises a controllable voltage regulation device, which is designed such that it outputs different output voltages as a function of a signal received at the data connection. This also has an advantageous effect on the use of the circuit arrangement according to the invention with different sensor types, since a hardware adaptation or change of the circuit arrangement is not necessary. Advantageous embodiments of the invention are specified in the subclaims.

Embodiments of the invention are shown by way of example in the figures. Show it:

1 shows a block diagram of a circuit arrangement according to the invention for data acquisition;

2 shows a circuit diagram of a circuit arrangement according to the invention for recording measured values;

FIG. 3 shows a block diagram of a first sensor which can be connected to the circuit arrangement according to FIG. 2;

FIG. 4 shows a block diagram of a second sensor which can be connected to the circuit arrangement according to FIG. 2; 1 shows a block diagram of a circuit arrangement according to the invention ... The circuit arrangement 1 has an input connection 3, which is used to establish a connection to an external sensor 5. The connection to the external sensor 5 is realized by an electrical line 7, which can consist of several signal and supply lines. A data connection 9, which is also provided on the circuit arrangement 1, serves to establish a connection to a data bus 11. The circuit arrangement 1 can communicate with a central control device 13 via the data bus 11. Further circuit arrangements (not shown) can be arranged on the data bus.

Furthermore, the circuit arrangement 1 comprises a processing device 15 and a voltage supply device 17. The processing device 15 has an input / output device 19, a control device 21, a switching device 23, a digital interface 25, an analog / digital converter 27, a voltage measuring device 29 , a current measuring device 31 and a resistance measuring device 33. The individual assemblies 19, 21, 23, 25, 27, 29, 31, 33 of the processing device 15 are connected to one another by bidirectional data lines.

A data line 35 leads from the data connection 9 to the input / output device 19. The input / output device 19 is connected via a data line 37 to the control device 21 and via a data line 39 to the switching device 23, which in turn is connected to the control via a data line 40 - Ereinrichtung 21 is connected. In each case one data line 41 leads from the switchover device 23 to that of the digital interface 25, the analog / digital converter 27, the voltage measuring device 29, the current measuring device 31 and the resistance measuring device 33. All of these assemblies 25, 27, 29, 31, 33 are connected via data lines 43 connected to the input terminal 3. The input / output device 19 receives and sends data via the data line 35 and the data connection 9 and converts this data into a form which can be processed by the other assemblies of the processing device 15. Conversely, the input / output device 19 processes the information provided in the processing device 15 for output to the data bus 11 into a form which can be transmitted on the data bus 11, for example the information coming from the external sensor 5 via the data line 39.

The control device 21 coordinates the interaction of the individual assemblies of the processing device 15, controls a voltage control device 45 provided in the voltage supply device 17 and activates or deactivates the external sensor 5. Certain control processes are firmly provided in the control device 21, and a large number of control processes can but are initiated by instructions which the central control device 13 sends to the circuit arrangement 1 via the data bus 11.

For example, the level of the voltage to be output by the voltage regulating device 45 can be determined by such an instruction. For this purpose, the control device 21 can act on the voltage regulating device 45. Furthermore, it is possible to control the switching device 23 via the data line 40 in such a way that the assembly 25, 27, 29, 31, 33 that matches the type of signal supplied by the sensor 5 is used.

If the sensor supplies a digital signal, for example, this is processed further by the digital interface 25, but if it is an analog signal, then the analog / digital converter 27 will be used accordingly. If the sensor signal consists of a voltage value, a current value or a resistance value, the voltage measuring device 29, the current measuring device 31 or the resistance measuring device 33 are used accordingly. The activation or deactivation of the external sensor 5 is achieved in that the control device 21 sets the voltage supplied to the external sensor 5 via a voltage supply line 49 to zero. This can be achieved by controlling the voltage regulating device 45 or by controlling an additional switching element (not shown).

The power supply device 17 takes the energy required to supply the circuit arrangement 1 and the external sensors 5 via a line 47 from the data line 35, which forwards the AC voltage used for signal transmission from the data connection 9 to the input / output device 19.

The individual voltage supply lines that lead from the voltage supply device 17 to the individual assemblies of the processing device 15 are not shown for the sake of clarity. The voltage supply line 49 leads from the controllable voltage regulating device 45 to the input connection 3. Via the control line 51, the control device 21 controls the level of the voltage output by the voltage regulating device 45.

FIG. 2 shows the circuit diagram of an embodiment of the circuit arrangement 1 according to the invention. The assemblies of the circuit arrangement 1 shown in FIG. 1 and described above can in principle also be found in the circuit diagram shown in FIG. 2. The input terminal 3 is formed by a multi-pin terminal block 60. The connection bar 60 contains the connections which are required for communication with analog and digital sensors. Connection 61 is used for the voltage supply. A status line lies on connection 62, a clock line on connection 63, a trigger line on connection 64, a line for digital signals on connection 65, a line for analog signals on connection 66 and a ground line on connection 67.

A two-wire line with connections 69 is provided as the data connection 9. On the one hand, two data lines 35 run from the connections 69 to a transmitter and receiver 71, which essentially corresponds to the input / output device from FIG. 1.

On the other hand, the connections 69 are connected via supply lines 47 to a bridge rectifier 73, which forms part of the voltage supply device of the circuit arrangement 1. The voltage VCCI rectified by the bridge rectifier 73 is smoothed by a first capacitor 75. This is connected via line 77 to the positive output of the bridge rectifier and via line 79 to the other output of the bridge rectifier, which represents the ground for circuit arrangement 1. The live contact of the first capacitor 75 is connected to a voltage converter 81. The voltage VCC2 output by the voltage converter 81 is preferably between 10 V and 20 V. The voltage converter 81 is followed by a second capacitor 83 connected to ground for smoothing the voltage VCC2 output by the voltage converter 81. The capacitors 75 and 83 also serve to store energy.

A line 85 leads the voltage VCC2 generated by the voltage converter 81 to a controllable voltage regulator 87, the output of which is connected to the terminal 61 of the terminal block 60. In addition, the voltage VCC2 is tapped from the line 85 and fed to a first input 88 of a first operational amplifier 89. A reference voltage is present at the second input 91 of the operational amplifier 89. The operational amplifier 89 compares whether the voltage VCC2 generated by the voltage converter 81 corresponds to the reference voltage. In front of the voltage converter 81, the voltage VCCI for supplying the transmitter and receiver 71 is taken. In addition, a control unit 93 is supplied with the voltage VCCI, which essentially has the functionality of the control device, the switching device, the digital interface and the analog / digital converter according to FIG. 1. In the control unit 93, an analog / digital converter 95 is provided which has two inputs and an internal multiplexer. With the analog / digital converter, on the one hand, the analog input signals from connection 66 and, on the other hand, the voltage applied via line 97 can be digitized and thus measured. A data line 99 is provided for communication between the control unit 93 and the transmitter and receiver 71.

A control line 101 leads from the control unit 93 to the voltage regulator 87. Through the control line 101, the control unit can influence the voltage output by the voltage regulator. A line 103 leads from the output of the first operational amplifier 89 to the control unit. The control unit receives the information of the comparison between the voltage VCC2 present at the first operational amplifier 89 and the reference voltage present at the input 91 via the line 103.

A current measuring device and a device for activating and deactivating an external sensor (cf. FIG. 1), which is connected to the terminal strip 60 during operation, comprises a first and a second N-channel field effect transistor (FET) 105, 107 connected to ground and a second operational amplifier 109. The external sensor can be activated and deactivated by the first N-channel FET 105. For this purpose, a control line 111 starting from the control unit 93 is provided, which is connected to the gate connection of the first N-channel FET 105. If this line is connected to ground by the control unit, the N-channel FET is blocked. All field effect transistors used in the circuit shown are namely self-blocking enhancement MOSFETs. The sensor is therefore deactivated. If no influence is exerted on the gate connection of the first N-channel FET 105 by the control line 111, this can be used to measure the current flowing through it and originating from the external sensor. The second operational amplifier 109 is connected with an input connection 113 to a second reference voltage, with the other input connection 115 with the drain connection and with the output connection with the gate connection of the first N-channel FET 105. With this arrangement, a control circuit is implemented which causes the drain-source voltage of the first N-channel FET 105 to always remain the same as the second reference voltage. This ensures that the current measurement carried out by the first N-channel FET 105 has no effect on the voltage made available to the external sensor 5.

The gate connections of the two N-channel FETs 105, 107 are connected to one another. The source connections are each connected to ground. For identical N-channel FETs, the identical gate-source voltage means that the source current of both N-channel FETs 105, 107 is also identical.

In the case of non-identical N-channel FETs 105, 107, the transmission ratio can be set by means of different area ratios. The advantage here is that the full sensor current does not have to be conducted via the internal current mirror.

A current mirror is implemented by means of a first and a second P-channel FET 117, 119 connected to the supply voltage VCC2 and a resistor 121. The gate-source voltages are also identical in the P-channel FETs 117, 119. Due to the identical gate-source voltage, it also follows for identical P-channel FETs that the source current of the P-channel FET 117, 119 is identical. This current mirror causes the current flowing through resistor 121 to be the same as that through second N-channel FET 107 flows, i.e. as high as the current from the external sensor via connection 67.

The voltage drop there is now tapped off from the resistor 121 and fed to the analog / digital converter 95 via the line 97. Conversely, the control unit can now calculate the strength of the measured current from the voltage drop across the resistor 121.

3 and 4 show an example of the wiring of external sensors that can be used with a circuit arrangement according to FIG. 2. 3 shows a Hall sensor 130. The Hall sensor 130 is connected to a voltage supply connection 61 and a ground connection 67 of a terminal strip 60. In this sensor, only the sensor current of the Hall sensor is measured by the circuit arrangement according to FIG. 2, since this represents the measurement signal.

4, a digital acceleration sensor 132 is shown. The digital acceleration sensor 132 is connected to a voltage supply connection 61, a connection 62 for a status line, a connection 63 for a clock line, a connection 64 for a trigger line, a connection 65 for digital signals and a connection 67 for a ground line. The digital acceleration sensor 132 is supplied with energy on the one hand via these connections and, on the other hand, communication with the circuit arrangement 1 according to FIG. 2 can take place via the connections.

Claims

claims

1. Circuit arrangement (1) for measured value acquisition with an input connection (3) for establishing a connection to an external sensor (5, 130, 132), a data connection (9) for establishing a connection to a data bus (11) and with Processing device (15), which converts input signals received via the input connection (3) into a form which can be transmitted via the data bus (11), characterized in that the processing device (15) has a switchover device (23) with which the adaptation circuits () 25, 27, 29, 31, 33) for adaptation to various types of external sensors (5, 130, 132) can optionally be connected to the input voltage connection (3), so that the processing device (15) processes various types of input signals and converts them into the transferable form can convert.

2. Circuit arrangement according to claim 1, characterized in that the processing device (15) has a digital interface (25) for processing a digital input signal.

3. Circuit arrangement according to claim 1 or 2, characterized in that the processing device (15) has an analog / digital converter (27, 95) for processing an analog input signal.

4. Circuit arrangement according to one of the preceding claims, characterized in that the processing device (15; a voltage measuring device (29, 95) for measuring a voltage applied to the input terminal (3).

5. Circuit arrangement according to one of the preceding claims, characterized in that the processing device (15) has a current measuring device (31) for measuring a current at the input connection (3).

6. Circuit arrangement according to one of the preceding claims, characterized in that the processing device (15) has a resistance measuring device (33) for measuring a resistance at the input terminal (3).

7. Circuit arrangement according to one of the preceding claims, characterized in that the switching device (23) is designed such that it adjusts the behavior of the processing device (15) to the type of input signal as a function of a signal received at the data connection (9).

8. Circuit arrangement according to one of the preceding claims, characterized in that the processing device (15) has a control device (21) for activating and deactivating the external sensor (5) connected to the input connection (3).

9. Circuit arrangement according to one of the preceding claims, characterized by a voltage supply device

(17) for supplying the external sensor (5) connected to the input connection (3) with energy.

10. Circuit arrangement according to claim 9, in which the signals present at the data connection (9) are alternated

Voltage are transmitted, characterized in that the power supply device device (17) takes the energy from the alternating voltage present at the data connection (9).

11. Circuit arrangement according to claim 9, in which the signals present at the data connection (9) are transmitted by a superimposed DC voltage, characterized in that the voltage supply device (17) takes the energy from the superimposed DC voltage applied to the data connection (9).

12. Circuit arrangement according to one of claims 9 to 11, characterized in that the voltage supply device (17) comprises a controllable voltage control device (45, 87), which is designed such that it different depending on a signal received at the data connection (9) Output voltages caused.

13. Method for recording measured values, in particular by means of a circuit arrangement (1) according to one of the preceding claims, consisting of the following steps: after receiving a request signal arriving via a data connection (9), a sensor located at an input connection (3) is first activated, the measured value supplied by the external sensor (5) is then detected, then the external sensor (5) is deactivated and the measured value is sent via the data connection (9).