JP2021061466A - Signal reading system - Google Patents

Abstract

To provide a signal reading system that generates a code identification signal capable of identifying a code indicated by a logic signal of a communication path to output it to an analysis device, and that gives notice when a signal collision with the analysis device occurs.SOLUTION: A signal reading system includes: a CAN driver 3 that converts a code identification signal Sf indicating a logic signal Sa into a transmission signal STX and outputs it from a pair of output terminals to an analysis device; a CAN receiver 5 that receives the signal generated between the pair of output terminals and outputs it as a reception signal SRX; a comparison unit 7 that compares logics of the code identification signal Sf and the reception signal SRX and outputs an output signal So indicating match/mismatch between the logics; and a processing unit 9 that performs notification operation when the output signal So (So1) indicating mismatch is input.SELECTED DRAWING: Figure 1

Description

The present invention is a signal that generates a code identification signal capable of specifying a code corresponding to a logic signal based on a logic signal transmitted via a CAN (registered trademark) bus and outputs the signal to an external CAN communication compatible device. It relates to a reading system.

For example, in the following patent documents, it is connected to an in-vehicle LAN as a serial bus represented by a CAN bus (connected to a 2-wire differential voltage type communication path, a power supply line, and a ground line constituting the in-vehicle LAN). A vehicle data collection device (hereinafter referred to as a vehicle data collection device) as a signal generation device configured to collect and record various data (data constituting a CAN frame) from an ECU (electronic control device) transmitted via this in-vehicle LAN. , Simply referred to as a "collector") is disclosed. This collection device is attached to a diagnostic connector (hereinafter, simply referred to as "connector") provided in the in-vehicle LAN so that an external CAN communication compatible device such as an analyzer (analyzer) can be connected for the purpose of failure diagnosis and maintenance. It is configured to be connectable. By connecting to the above-mentioned connector, this collecting device is directly connected to the in-vehicle LAN (the above-mentioned communication path, power supply line and ground line) via this connector. In this collecting device, when connected to the above connector, it operates by the power supply supplied through this connector, and data from the in-vehicle LAN (specifically, the above communication path) is linked to the operation of the ignition switch. A configuration is adopted that automatically starts / stops the collection of. Further, when the collecting device cannot collect the data from the ECU to be collected, the collecting device transmits a data retransmission request to the ECU via the in-vehicle LAN, and the data from the ECU responding to the request. Is configured to receive and collect.

Japanese Unexamined Patent Publication No. 2008-70133 (Pages 4-11, Fig. 1-17)

By the way, the above-mentioned connector provided in the in-vehicle LAN is normally compatible with CAN communication, which is assumed to be connected by the vehicle developer (manufacturer) for the purpose of failure diagnosis and maintenance of the vehicle after shipment. It is a connector for connecting a device (for example, an analyzer (analyzer) for failure diagnosis or maintenance provided by a manufacturer). Therefore, when attempting to perform vehicle failure diagnosis or maintenance after shipment, it is necessary to prepare a dedicated analysis device corresponding to the vehicle (or the manufacturer of the vehicle). However, there are cases where it is necessary to carry out failure diagnosis, etc. for vehicles of multiple manufacturers, and in such cases, it is necessary to prepare a dedicated analysis device for each manufacturer, which is troublesome and costly. There is a problem that it takes.

Further, in recent years, a device that outputs a malicious CAN frame for the purpose of obstructing the operation of various ECUs connected to the in-vehicle LAN is connected to a connector, or a CAN frame transmitted via the in-vehicle LAN is malicious. It has been confirmed that a device that transfers to a third party via a mobile communication network or the like is connected to a connector. Therefore, at a vehicle development site or the like, from the viewpoint of security, the adoption of a configuration in which the above connector is not arranged in the in-vehicle LAN is being considered. However, when such a configuration is adopted, the above-mentioned dedicated analysis device, which is premised on connecting to the in-vehicle LAN via a connector, can perform vehicle failure diagnosis and maintenance after shipment. The problem arises that it becomes difficult.

Although the problems in the field of automobiles have been illustrated, in fields other than automobiles, for example, in the field of machinery and equipment in factories, there is a configuration in which a dedicated analysis device is connected via a dedicated connector as described above. Since it is adopted, the above-mentioned is used when acquiring a CAN frame (a string of codes indicated by a logic signal of a 2-wire differential voltage system) transmitted via a serial bus (communication path) for CAN communication. A problem similar to the problem is occurring.

Therefore, in order to solve this problem, the applicant of the present application has a configuration in which the communication path (CAN bus) is interposed between the communication path (CAN bus) and a CAN communication compatible device such as an analyzer and connected to the communication path via a connector. Instead, it is configured to be connected to the communication path by capacitive coupling, and it reads (detects) the logic signal transmitted to the communication path, generates a code identification signal that can specify the code indicated by this logic signal, and Prior applications (Japanese Patent Application No. 2019-133340, Japanese Patent Application No. 2019-133343, etc.) have been filed for a signal reading system capable of outputting the generated code identification signal to a CAN communication compatible device.

However, as described above, the existing CAN communication compatible device described above has a configuration in which data is transmitted / received to / from the ECU connected to the same communication path together with the CAN communication compatible device (for example, a transmission request to the ECU). Is transmitted, and when data is transmitted from the ECU in response to this transmission request, this data is received, and when the data is normally received, an ACK indicating this is transmitted).

On the other hand, the signal reading system of the applicant of the present application proposed in the above-mentioned prior application is for code identification capable of reading (detecting) a logic signal transmitted to a communication path and identifying a code indicated by this logic signal. Of the pair of covered conductors that make up the CAN bus, when the signal is generated and the signal matches the input specifications of the CAN communication compatible device (when the CAN communication compatible device is connected to the serial bus (CAN bus) for CAN communication) A voltage signal with the same signal waveform as the voltage signal transmitted to the CANH coated wire and a voltage signal with the same signal waveform as the voltage signal transmitted to the CANLow (CANL) covered wire) are converted to CAN. It has only the function of transmitting (outputting) to communication compatible devices. That is, this signal reading system does not receive the signal (data) transmitted from the CAN communication compatible device (that is, does not output the signal transmitted from the CAN communication compatible device to the communication path). It is adopted.

Because of this configuration, the applicant's signal reading system uses a CAN driver (in this signal reading system, for example, a CAN driver in a commercially available CAN transceiver configured to be housed in one package with a CAN receiver). Then, the code identification signal is converted into a signal that matches the input specifications of the CAN communication compatible device, but this CAN receiver is not used (as a result, communication between the signal reading system and the CAN communication compatible device). (Structure without mediation) is adopted.

Therefore, in the signal reading system of the applicant of the present application, the CAN communication compatible device is not provided with a measure for stopping the output of the signal to the transmission line connecting the signal reading system and the CAN communication compatible device. It is preferable that each signal transmitted from both the signal reading system and the CAN communication compatible device collides with each other at this transmission line (a pair of output terminals of the CAN driver connected to this transmission line). Absent. However, since the signal reading system of the applicant of the present application does not have a function of notifying the user of the signal reading system that a collision of the signals has occurred, improvement is desired.

The present invention has been made in view of the problem to be solved, and it is possible to specify the code indicated by the logic signal transmitted to the communication path without being directly connected to the communication path via the connector. Provided is a signal reading system capable of generating a specific code identification signal and outputting it to a CAN communication compatible device, and also notifying the occurrence of this collision when a signal collision occurs with the CAN communication compatible device. Is the main purpose.

In order to achieve the above object, the signal reading system according to claim 1 is connected to an electrode arranged in a state close to a covered lead wire constituting a CAN bus to which a logic signal conforming to the CAN communication protocol is transmitted. A code identification signal that can generate a voltage signal whose voltage changes according to the voltage transmitted to the coated lead wire that is capacitively coupled to the electrode and can specify a code corresponding to the logic signal based on the voltage signal. It is provided with a signal generator for generating the code, and a CAN driver that converts the code identification signal into a transmission signal conforming to the same CAN communication protocol as the logic signal and outputs the signal from the output terminal to an external CAN communication compatible device. In a signal reading system, a CAN receiver that receives a signal generated at the output terminal, converts it into a voltage signal and outputs it as a reception signal, inputs the code identification signal and the reception signal, and receives the code. When the logic of the specific signal is compared with the logic of the received signal and the comparison unit that outputs the output signal indicating the match / mismatch between the logics and the output signal indicating the mismatch are input, the notification operation is performed. It has a processing unit to execute.

Further, the signal reading system according to claim 2 is connected to an electrode arranged in a state close to a coated lead wire constituting a CAN bus to which a logic signal conforming to the CAN communication protocol is transmitted, and is connected to the electrode and a capacitance. A signal that generates a voltage signal whose voltage changes according to the voltage transmitted to the coated lead wire to be coupled, and also generates a code identification signal that can specify a code corresponding to the logic signal based on the voltage signal. A signal reading system including a generator and a CAN driver that converts the code identification signal into a transmission signal conforming to the same CAN communication protocol as the logic signal and outputs the signal from an output terminal to an external CAN communication compatible device. There is a CAN receiver that receives the signal generated at the output terminal, converts it into a voltage signal and outputs it as a reception signal, and inputs the code identification signal and each signal at the CAN driver and the CAN receiver. A delay unit that delays a time equivalent to the total propagation delay time and outputs it as a delay code specifying signal, inputs the delay code specifying signal and the received signal, and the logic of the delay code specifying signal. A comparison unit that compares the logic of the received signal and outputs an output signal indicating match / mismatch between the logics, and a processing unit that executes a notification operation when the output signal indicating the mismatch is input. I have.

Further, the signal reading system according to claim 3 is the signal reading system according to claim 1 or 2, wherein the CAN bus is composed of a pair of the coated conducting wires, and the signal generating device is close to the pair of coated electric wires. A pair of the voltage signals that are connected to the pair of the electrodes arranged in the above-mentioned state and whose voltage changes according to the voltage transmitted to the pair of coated conductors that are capacitively coupled to the pair of electrodes are generated. At the same time, the code identification signal is generated based on the pair of voltage signals, the CAN driver outputs the transmission signal from the pair of output terminals, and the CAN receiver is generated at the pair of output terminals. Receives the signal.

Further, the signal reading system according to claim 4 is arranged between the comparison unit and the processing unit in the signal reading system according to any one of claims 1 to 3, and is output from the comparison unit. A low-pass filter that removes high-frequency components contained in the output signal and outputs the signal to the processing unit is provided.

Further, the signal reading system according to claim 5 includes an output unit in the signal reading system according to any one of claims 1 to 4, and the processing unit indicates that the logics do not match each other. The operation of outputting to is executed as the notification operation.

According to the signal reading system according to claims 1 and 3, the logic signal transmitted to the CAN bus is read (that is, the connector is connected) by capacitively coupling with one or a pair of covered conductors constituting the CAN bus. By reading without being directly connected to the communication path via the communication path), it is possible to generate a code identification signal capable of specifying the code corresponding to the logic signal and output it to a CAN communication compatible device, and a CAN receiver as described above. By providing a comparison unit and a processing unit, a signal collision has occurred between the CAN driver and a CAN communication compatible device, that is, a measure for stopping the output of the signal to the signal reading system is supported by CAN communication. It is possible to notify the user that the device has not been applied.

Further, according to the signal reading system according to claims 2 and 3, the logic signal transmitted to the CAN bus is read (that is, by capacitively coupling with one or a pair of covered conductors constituting the CAN bus). By reading without being directly connected to the communication path via the connector), it is possible to generate a code identification signal capable of specifying the code corresponding to the logic signal and output it to a CAN communication compatible device. Further, in this signal reading system, since the CAN receiver, the delay unit, the comparison unit, and the processing unit as described above are provided, when the received signal is delayed with respect to the code identification signal, the delay unit becomes this delay unit. The code specification signal can be delayed by the delay and output as a delay code specification signal. Therefore, when the signal collision does not occur, the comparison unit can accurately compare the received signal having almost the same phase with the delay code specifying signal, and thus the output signal indicating the match / mismatch between the logics. Can be output accurately. As a result, based on this output signal, the processing unit reliably executes the notification operation when it indicates a mismatch (when a signal collision occurs between the CAN driver and the CAN communication compatible device). be able to. Therefore, according to this signal reading system, even when the received signal is delayed with respect to the code identification signal, a signal collision occurs between the CAN driver and the CAN communication compatible device. That is, it is possible to notify the user that the measures for stopping the output of the signal to the signal reading system have not been taken for the CAN communication compatible device.

Further, according to the signal reading system according to claim 4, since the low-pass filter is provided, the high frequency component contained in the output signal can be reliably removed and output to the processing unit, which is caused by this noise. Therefore, it is possible to avoid the occurrence of a situation in which the processing unit mistakenly executes the notification operation.

Further, according to the signal reading system according to claim 5, a signal collision between the CAN driver and the CAN communication compatible device is provided by providing an output unit for outputting that the logics do not match as described above. It is possible to save the trouble of separately providing an output device such as a display device or a sound emitting device for notifying the user that the above is occurring.

It is a block diagram which shows the structure of the signal reading system 1A. It is a waveform diagram of the code Cs, the voltage Va, Vb, the voltage signal Vc1, Vc2, the voltage signal Vd1, Vd2, and the code specifying signal Sf. It is a circuit diagram about one specific example of a delay part 6. It is a block diagram which shows the structure of the signal reading system 1B.

Hereinafter, embodiments of the signal reading system will be described with reference to the accompanying drawings.

As shown in FIG. 1, the signal reading system 1A as a signal reading system includes, as an example, a pair of probes PLa, PLb, a signal generator 2A, a CAN driver 3, an output connector 4, a CAN receiver 5, a delay unit 6, and a comparison. A unit 7, a low-pass filter 8, a processing unit 9, and an output unit 10 are provided. Further, the signal reading system 1A is via a serial bus SB for CAN communication (hereinafter, also referred to as a CAN bus SB) composed of a pair of signal lines (for example, a pair of coated lead wires La and Lb) and a CAN bus SB. This logic signal Sa is read (detected) by being interposed between the analyzer (analyzer) for analyzing the logic signal Sa of the 2-wire differential voltage system transmitted, and corresponds to this logic signal Sa. A signal Sf for specifying a code that can specify the code to be specified is generated, and the signal Sf for specifying the code is used as a transmission signal _STX (2-wire differential voltage system logic conforming to the CAN communication protocol) that matches the input specifications of the analyzer. It is converted into a signal) and output to the analyzer.

In the signal reading system 1A, as this logic signal Sa, various "two-wire differential voltage system logic signals" compliant with various CAN communication protocols such as "CAN protocol" and "CAN FD" are targeted. be able to. In this case, in the CAN bus SB on which this logic signal Sa is transmitted, the "high potential side signal line (CANH) / low potential side signal line (CANL)" becomes a "pair of covered conductors for transmitting the logic signal". Equivalent to. In the following, as an example of the CAN bus SB, an example in which the signal reading system 1A is applied to the CAN bus arranged in the automobile will be described, but the present invention is not limited to this, and the machine in the factory as described above is not limited thereto. This signal reading system 1A can also be applied to CAN buses used in the field of equipment.

As shown in FIG. 1, in the CAN bus SB, the logic signal Sa representing each code Cs (see FIG. 2) constituting the CAN frame is a pair of covered lead wires La, Lb forming the CAN bus SB as described above. Of the voltage signal Va (hereinafter, for the sake of easy understanding, this voltage signal itself is also referred to as a voltage signal Va) and a pair of coated conductors La, Lb. The potential difference (Va-Vb) between the voltage Vb of the voltage signal transmitted to the coated lead wire Lb of our CANLow (CANL) (hereinafter, this voltage signal itself is also referred to as the voltage signal Vb for easy understanding). It is transmitted as a differential signal.

Since the transmission principle of the logic signal Sa via the CAN bus SB is known, detailed description thereof will be omitted, but the specifications of the CANH (CANH) voltage signal Va and the CANLow (CANL) voltage signal Vb are simple. Explain to. As shown in FIG. 2, the voltage signals Va and Vb are voltage signals that change in the opposite direction from the base voltage (+ 2.5 V), and when the voltage signal Va is the voltage of this base, the voltage signal Vb is also The code Cs (logical value) constituting the CAN frame transmitted during this period when the voltage is the same base voltage over the same period and the potential difference (Va-Vb) becomes zero (minimum) indicates "1". Become. On the other hand, when the voltage signal Va is a specified voltage (+ 3.5 V) higher than the base voltage, the voltage signal Vb is conversely another specified voltage (+1) lower than the base voltage for the same period. .5V), and the code Cs (logical value) constituting the CAN frame transmitted during this period when the potential difference (Va-Vb) is maximized indicates "0". In addition, "SG", which is a signal line serving as a reference potential for transmitting a differential signal on the CAN bus SB, and signal lines and power lines (power supply line and ground) arranged for purposes other than transmission of the differential signal. The illustration and description of the line) etc. will be omitted.

The pair of probes PLa and PLb are configured in the same manner as a metal non-contact type probe by using a shielded cable (for example, a coaxial cable). Specifically, the probe PLa is connected to a core wire (not shown) of the coated lead wire La on the free end side (free end portion) which is detachably connected to the corresponding coated lead wire La (connected by capacitive coupling). The electrode portion 21a is arranged, and the base end side (base end portion) is connected (fixed) to the corresponding input terminal portion 31 of the input terminal portions 31 and 32 described later of the signal generation device 2A. A connection connector (not shown) (which is connected to the target or detachably) is arranged and configured. Further, the probe PLb is an electrode connected to a core wire (not shown) of the coated conductive wire Lb on the free end side (free end portion) removably connected to the corresponding coated conductive wire Lb (connected by a capacitive coupling). The portion 21b is arranged, and is connected to the corresponding input terminal portion 32 of the above input terminal portions 31 and 32 (fixed or detachably connected) on the proximal end side (base end portion). A connection connector (not shown) is arranged and configured.

As shown in FIG. 1, the electrode portion 21a contacts (contacts) an insulating coating portion (hereinafter, also simply referred to as “coating portion”) of the coating conductor La, which is not shown, in a state of being connected to the coated conductor La. By covering the contact portion between the electrode 22a, which is capacitively coupled to the core wire (conductor itself (metal part)) of the coated conductor La, and the electrode 22a in the coated portion of the coated conductor La, including the electrode 22a, the electrode It is provided with a shield 23a for preventing capacitance coupling with another metal portion of 22a (a metal portion other than the core wire of the coated conductor La). Further, the electrode 22a is connected to the first detection unit 33 of the signal generation device 2A, which will be described later, via the core wire of the shielded cable constituting the probe PLa and one terminal of the input terminal unit 31. Further, the shield 23a is connected to a reference potential portion (ground G) in the signal generator 2A via the shield of the shielded cable and other terminals of the input terminal portion 31.

Further, as shown in FIG. 1, the electrode portion 21b is in contact with (contacting) an insulating coating portion (hereinafter, also simply referred to as “coating portion”) of the coated conductor Lb (hereinafter, also simply referred to as “covered portion”) in a state of being connected to the coated conductor Lb. ), By covering the contact portion between the electrode 22b, which is capacitively coupled to the core wire (conductor itself (metal part)) of the coated conductor Lb (not shown), and the electrode 22b in the coated portion of the coated conductor Lb, including the electrode 22b. The electrode 22b is provided with a shield 23b for preventing capacitance coupling with another metal portion (a metal portion other than the core wire of the coated conductor Lb). Further, the electrode 22b is connected to the second detection unit 34 of the signal generation device 2A, which will be described later, via the core wire of the shielded cable constituting the probe PLb and one terminal of the input terminal unit 32. Further, the shield 23b is connected to a reference potential portion (ground G) in the signal generator 2A via the shield of the shielded cable and other terminals of the input terminal portion 32.

Further, although not shown, each probe PLa, PLb has a corresponding coating so that the probe PLa can be correctly connected to the corresponding coated lead wire La and the probe PLb can be correctly connected to the corresponding coated lead wire Lb. Marks and the like for clearly indicating the conductors La and Lb (for example, the letters "CANH" and "CANL" indicating the coated conductors La and Lb to be connected) are displayed.

As shown in FIG. 1, the signal generation device 2A includes input terminal units 31, 32, a first detection unit 33, a second detection unit 34, and a signal generation unit 35A.

The input terminal portion 31 is composed of a connection connector arranged on the proximal end side of the probe PLa and a connection connector that can be connected. Further, the input terminal portion 32 is composed of a connection connector that can be connected to a connection connector arranged on the proximal end side of the probe PLb.

As an example, as shown in FIG. 1, the first detection unit 33 includes an impedance element 33a and an amplifier 33b, and the voltage transmitted to the coated lead wire La connected via the input terminal unit 31 and the probe PLa. A voltage signal Vd1 whose voltage changes according to Va is output. This voltage signal Vd1 is different from the differential voltage type voltage signal in which the code (data) is represented by the potential difference (Va-Vb) between the two as in the voltage signals Va and Vb described above, and the code (data) is obtained only by its own voltage. ) (That is, a voltage signal that is not a differential voltage system). Hereinafter, for the sake of explanation, a voltage signal of the same type as the voltage signal Vd1 is also referred to as a “non-differential voltage type voltage signal”.

As an example, the impedance element 33a is configured to include a resistance (a resistance having a high resistance value (a high impedance resistance of at least several MΩ)) and a capacitor connected in parallel to the resistance, as shown in FIG. The voltage changes according to the voltage Va transmitted to the coated lead wire La connected via the input terminal portion 31 and the probe PLa (when the voltage Va is the base voltage, the voltage becomes low, and when the voltage Va is high, the voltage changes. A non-differential voltage type voltage signal that changes so as to become a high voltage) A voltage signal Vc1 is output. The amplifier 33b is configured by a non-inverting amplifier as an example, and this voltage signal Vc1 is non-inverting amplified and output as a voltage signal Vd1 as shown in FIG.

As an example, as shown in FIG. 1, the second detection unit 34 includes an impedance element 34a and an amplifier 34b, and the voltage transmitted to the coated lead wire Lb connected via the input terminal unit 32 and the probe PLb. A voltage signal Vd2 (voltage signal of a non-differential voltage system) whose voltage changes according to Vb is output.

In this case, the impedance element 34a is configured in the same manner as the above-mentioned impedance element 33a, and the voltage changes according to the voltage Vb transmitted to the coated lead wire Lb connected via the input terminal portion 32 and the probe PLb. (A non-differential voltage system voltage signal that changes so that when the voltage Vb is the base voltage, it becomes a high voltage and when the voltage Vb is a low voltage, it becomes a low voltage) The voltage signal Vc2 is output. Further, the amplifier 34b is also configured in the same manner as the amplifier 33b described above, and the voltage signal Vc2 is non-inverting and amplified to obtain a voltage signal Vd2 (a voltage signal whose phase is inverted with respect to the voltage signal Vd1) as shown in FIG. ) Is output.

The amplifiers 33b and 34b are not limited to those composed of non-inverting amplifiers, and may be composed of inverting amplifiers. Further, the amplifiers 33b and 34b may be configured to amplify the DC component together with the AC component included in the corresponding voltage signals Vc1 and Vc2 (a configuration as a DC amplifier), or the AC included in the voltage signals Vc1 and Vc2. A configuration that amplifies only the components (a configuration that uses an AC amplifier) may be used.

The signal generation unit 35A inputs each voltage signal Vd1 and Vd2, and generates and outputs a code identification signal Sf based on the difference voltage (Vd1-Vd2) of each voltage signal Vd1 and Vd2. In this case, the signal generator 35A is connected to the coated conductor La to which the probe PLa should be connected (correctly connected to the coated conductor La) and connected to the coated conductor Lb to which the probe PLb should be connected (correctly coated). In the state of being connected to the lead wire Lb), as shown in FIG. 2, the reference numeral Cs (“1”) constituting the CAN frame (code sequence) on the CAN bus SB is based on the differential voltage (Vd1-Vd2). Code identification signal Sf (non-differential voltage method) that becomes a high potential side voltage (recessive) during the period when is transmitted and becomes a low potential side voltage (dominant) during the period when the code Cs (“0”) is transmitted. (Voltage signal) is correctly generated and output. As described above, in the code identification signal Sf, the period of the high potential side voltage (recessive) corresponds to the transmission period of the code Cs (“1”), and the period of the low potential side voltage (dominant) corresponds to the code Cs (“0”). Since it is a signal corresponding to the transmission period of (”), it is a signal capable of specifying the code Cs (“1”, “0”) corresponding to the logic signal Sa.

With the above configuration, in the signal generator 2A, as shown in FIG. 1, the probe PLa connected to the input terminal portion 31 is connected to the coated lead wire La, and the probe PLb connected to the input terminal portion 32 is the covered lead wire. In the state of being connected to Lb, the code identification signal Sf shown in FIG. 2 as described above is correctly generated and output.

As shown in FIG. 1, the CAN driver 3 functions as a signal conversion device, inputs a code identification signal Sf, and uses the code identification signal Sf as a transmission signal conforming to the same CAN communication protocol as the logic signal Sa. It _{is converted to STX} (2-wire differential voltage type logic signal) and output from a pair of output terminals.

The output connector 4 is composed of, for example, the same connector as the diagnostic connector described in the background art. Further, in the output connector 4, the pin 4a (one terminal) corresponding to the pin to which the CANHig signal is assigned in this diagnostic connector has the same specifications as the CAN bus SB (for example, 60Ω as the resistance value equivalent to the CAN bus SB). One of the pair of transmission lines Lg and Lh (internal bus ISB having the same characteristic impedance as the CAN bus SB) (specification in which the resistors 41 of) are connected to each other), the pair of transmission lines Lg (the pair of CAN drivers 3). Pin 4b (the other) that is connected to the output terminal (transmission line connected to one output terminal to which the CANLow voltage signal Vg is output) and corresponds to the pin to which the CANLow signal is assigned in this diagnostic connector. Transmission in which the terminal) is connected to the other transmission line Lh of the pair of transmission lines Lg and Lh (the other output terminal to which the CANLow voltage signal Vh of the pair of output terminals of the CAN driver 3 is output). Line) is connected.

Therefore, for easy understanding, each voltage of each voltage signal Vg, Vh is referred to as voltage Vg, Vh (voltage Vg has the same specifications as the above-mentioned voltage Va, and voltage Vh has the same specifications as the above-mentioned voltage Vb). When expressed, the above-mentioned transmission signal _STX is a pair of transmission lines Lg from the CAN driver 3 as a differential signal whose voltage is represented by a potential difference (Vg−Vh) between each voltage Vg and Vh. The voltage is output to Lh (internal bus ISB), and is further output to an external analyzer from the output connector 4 connected to the internal bus ISB together with the pair of output terminals of the CAN driver 3 as described above.

In the CAN receiver 5, the pair of input terminals are connected to the pair of output terminals of the CAN driver 3 (which are also the transmission lines Lg and Lh constituting the internal bus ISB connected to the pair of output terminals), and the pair of output terminals are connected. A signal generated between them (that is, a signal transmitted to the transmission lines Lg and Lh (two-wire differential voltage system logic signal)) is input, and a non-differential voltage system voltage signal (sign identification signal Sf) is input. It is converted into a signal with the same voltage level) and output as _{a received signal SRX.}

With this configuration, when the signal generated between the pair of output terminals of the CAN driver 3 (the signal transmitted to the internal bus ISB) is the transmission signal _STX itself, the CAN receiver 5 uses the voltage for code identification. and it outputs the received signal S _RX to in synchronism with the signal Sf becomes a high potential (recessive) and low potential (dominant). However, the received signal _{S RX} is the relative phase of the code specific signal Sf phase, signal propagation delay time tdr total time _{t ALL} of the signal propagation delay time tdt and CAN receiver 5 of the CAN driver 3 (= The signal is delayed by the same amount of time as (tdt + tdr). Generally, the CAN driver 3 and the CAN receiver 5 are packaged (closely arranged) as a CAN transceiver as described above. Therefore, the propagation time of the transmission signal _{S TX} from the CAN driver 3 on the internal bus ISB to CAN receiver 5 is assumed to be negligible.

The delay unit 6 is composed of a known delay circuit (for example, an RC type filter (see FIG. 3), an LC type filter, a buffer in which one or two or more are connected in series). Further, the delay unit 6 inputs the code specifying signal Sf, delays the code specifying signal Sf by a preset delay time, and outputs the delay code specifying signal Sfd. The delay time, the signal propagation delay time tdt defined in the product specification of the CAN driver 3 and the CAN receiver 5, tdr total time t _ALL calculated from (catalog specifications of each product) theoretical values and a plurality of the average value of the time difference between the actually measured code specifying signal Sf and the received signal S _RX in the signal reading system 1A (experimental value) is used. In this example, as an example, it is assumed that the theoretical value _{of the above total time t ALL is set as a preset delay time.}

Thus, the delay unit 6, a code specifying signal Sf inputted, delayed by the signal propagation delay time in the CAN driver 3 and the CAN receiver 5 are used tdt, total tdr time _{t ALL} equivalent time Then, it is output as a delay code specifying signal Sfd. With this configuration, when the signal being transmitted to the internal bus ISB is itself transmitted signal S _TX is delay code specific signal Sfd and received signal S _RX is in a state whose phase is substantially uniform.

Comparing unit 7 inputs the delay code specific signal Sfd and received signals S _RX, a logic (or a low potential or a high potential) of the delay code specifying signal Sfd and logical (high received signal S _RX It compares the low potential at either) and whether the potential, the result of the comparison (both signals Sfd, and outputs an output signal So indicating the match or mismatch) of the logic between the S _RX. Comparator 7 in the present example is constituted by EXOR circuit as shown in FIG. 1 as an example, the case where the logic of the logic and the received signal S _RX delay code specifying signal Sfd match (both signals Sfd, logic S _RX is, when both the high-potential, or both at low potential), becomes a low potential, whereas, when the logic of the logic and the received signal S _RX delay code specifying signal Sfd do not match (both signal Sfd, whereas a high potential of the logic of S _RX, the other in the case of a low potential), and outputs an output signal So at a high potential.

Here, the logic of the logic and the received signal S _RX delay code specifying signal Sfd will be described for the case of two of the mismatch. First, in the first case, the analysis device connected to the output connector 4 of the signal reading system 1A is not stopped from outputting signals to the transmission lines Lg and Lh, and the analysis device is used. This is a case where a signal is output between the pair of output terminals of the CAN driver 3 (transmission line Lg, Lh). _{In this case, the transmission signal STX} from the CAN driver 3 of the signal reading system 1A and the signal from the analysis device collide on the transmission lines Lg and Lh. Therefore, the waveform of the signal transmitted to the transmission lines Lg and Lh _{is different from the waveform of the transmission signal STX} that should be originally transmitted (the waveform corresponding to the logic of the code specifying signal Sf). Therefore, from the CAN receiver 5 that receives the transmission signal S _TX of this waveform, the period during which this different waveforms, logic different from the logic of the code specifying signal Sf (also the logic of the delay code specifying signal Sfd) The reception signal _SRX is output. Further, when the signal collision occurs in this way, the logic of the code specifying signal Sf (specifically, usually, for a period close to at least one bit length (for example, several μs) of the logic signal Sa). thereof include the logic of the received signal S _RX and logical) of the delay code specifying signal Sfd is the state where a mismatch repeatedly occurs. As a result, the output signal So is a pulse signal having a high potential with a pulse width over a period close to at least one bit length of the logic signal Sa (hereinafter, a “wide pulse signal” is used to distinguish it from noise described later. Also called) is a signal that is repeatedly included.

Next, in the second case, a measure is taken to stop the output of the signal to the transmission lines Lg and Lh for the analyzer connected to the output connector 4 of the signal reading system 1A, and the CAN driver 3 only the transmission signal S _TX from is in a state being output transmission line Lg, the Lh, but the delay time which is previously set in the delay unit 6, the actual signal propagation delay time tdt and cAN receiver in cAN driver 3 5 is a case that does not match the actual signal propagation delay time tdr total time _t ALL of (= tdt + tdr) in. Actually, the signal propagation delay time tdt in the CAN driver 3 and the signal propagation delay time tdr in the CAN receiver 5 change depending on the ambient temperature or vary depending on the CAN transceiver (within the allowable range of the product specifications). (Variates in). Therefore, the actual total time t _ALL slightly deviates from the delay time (theoretical value of the _{total time t ALL} ) predetermined for the delay unit 6.

_{In this case, the total time t ALL of the} actual signal propagation delay times tdt and tdr of the CAN driver 3 and the CAN receiver 5 when the phase of the code identification signal Sf is used as a reference (actual total time t _ALL ). in the received signal S _RX is delayed, between the theoretical values and the sum defined in the experimental value time t _ALL delay code specifying signal Sfd _(this example in the theoretical value, for example) is delayed by the above Causes a phase difference. Thus, the logic of the logic and the received signal S _RX delay code specifying signal Sfd, although a state that matches over the most time, the logic of the delay code specific signal Sfd and received signal S _RX with low potential The rising timing of shifting from high potential to high potential by this phase difference and the falling timing of shifting from high potential to low potential by this phase difference are inconsistent for the time of this phase difference. Therefore, the output signal So output from the comparison unit 7, although basically it is a signal of a state close to the level signal of low potential, falling and the rising timing of the delay code specific signal Sfd and received signals S _RX At the falling timing, it becomes a signal in which noise (whisker-shaped pulse signal) that temporarily becomes a high potential is generated for the time of this phase difference. This noise (whisker-shaped pulse signal) is extremely higher than the basic frequency of the logic signal Sa (for example, a signal with a pulse width of about several tens of ns, which is sufficiently short for one bit length (for example, several μs) of the logic signal Sa. It becomes a signal composed of frequency components (for example, high frequency components that are several tens of times higher).

Note that the logic of the output signal So, the above example of the logical (both signals Sfd, becomes a low potential when the logic matching of S _RX, logic a higher potential when the mismatch) is not limited to, by inverting the output of the EXOR circuit, reverse logic may be (both signals Sfd, becomes a high potential when the logic matching of S _RX, logic becomes a low potential when the mismatch).

The low-pass filter 8 is arranged between the comparison unit 7 and the processing unit 9, and when the output signal So output from the comparison unit 7 contains a high frequency component (the above noise), the high frequency component (the above noise) is included. The above noise) is removed (including attenuating to a voltage lower than a predetermined threshold voltage in addition to completely attenuating to a low potential), and the new output signal So1 is output to the processing unit 9. On the other hand, the low-pass filter 8 is close to the above-mentioned pulse signal (at least one bit length of the logic signal Sa) that is repeatedly included in the output signal So when the above-mentioned signal collision occurs in the transmission lines Lg and Lh. A pulse signal that has a high potential over a period of pulse width) cannot be removed (it cannot be attenuated below the above threshold voltage). Therefore, in this case, the low-pass filter 8 includes the pulse signal (wide pulse signal) having this pulse width in the output signal So1 in a state of the above threshold voltage or more and outputs the pulse signal. Although not shown, the low-pass filter 8 can be composed of various known filter circuits such as an RC type filter and an LC type filter.

Processor 9 inputs the output signal So1 is outputted from the low pass filter 8, the output signal So1 is the result of the comparison between the logic of the received signal S _RX to the logic of the delay code specifying signal Sfd do not match When it is detected that the signal indicates the above, the notification operation is executed. Specifically, the processing unit 9 detects the voltage of the output signal So1 and compares it with the above threshold voltage, and when the detected voltage becomes equal to or higher than the above threshold voltage, the output signal So1 is delayed. detecting a shows the results of comparison between the logic of the logic to the received signal S _RX code specifying signal Sfd do not match. The processing unit 9 as the notification operation, executes the operation to output to the output unit 10 to the logic of the received signal S _RX to the logic of the delay code specifying signal Sfd do not match.

Although not shown, the processing unit 9 can be composed of, for example, a comparator, a monostable multivibrator circuit, and a buffer. In this case, as an example, the comparator compares the voltage of the output signal So1 with the above threshold voltage, and outputs a pulse having a high potential when the voltage of the output signal So1 is equal to or higher than this threshold voltage. As an example, the monostable multivibrator circuit outputs a pulse having a high potential for a predetermined time when a high potential pulse is input from a comparator. In this case, this predetermined time is the above-mentioned wide pulse signal (this wide pulse signal is repeatedly included in the output signal So when the above-mentioned signal collision occurs in the transmission lines Lg and Lh. It is assumed that the time specified is longer than the maximum time of the output signal So1). With this configuration, when the above-mentioned signal collision occurs in the transmission lines Lg and Lh, the monostable multivibrator circuit outputs a level signal having a high potential. In this case, when the above-mentioned signal collisions occur continuously on the transmission lines Lg and Lh, the monostable multivibrator circuit continuously outputs a level signal having a high potential. The buffer outputs the signal output from the monostable multivibrator circuit as a control signal Ss for the output unit 10 with low impedance.

The processing unit 9 is not limited to this configuration. For example, the processing unit 9 may be composed of an A / D converter and a computer. In this case, the A / D converter samples the output signal So1 at a constant sampling cycle to output waveform data indicating an instantaneous value of the output signal So1. When the computer inputs this waveform data and compares it with the threshold data indicating the above threshold voltage stored in advance and determines that the waveform data is equal to or greater than the threshold data, the computer sends the control signal Ss to the output unit 10. Is output over the above-mentioned predetermined time. Also in this configuration, the processing unit 9 operates in the same manner as the configuration including the comparator, the monostable multivibrator circuit, and the buffer, and outputs the equivalent control signal Ss.

Further, when the processing unit 9 is configured by the A / D converter and the computer in this way, the output signal So is converted into waveform data by the A / D converter and output to the computer. , The function of the low-pass filter 8 may be realized by software. Further, when the above noise contained in the output signal So can be removed by sampling with the A / D converter (the sampling timing with the A / D converter is usually different from the generation timing of this noise. Since it is asynchronous. Therefore, when the noise generation time is short, this noise may be removed by sampling with an A / D converter), the low-pass filter 8 can be omitted. In this case, it is not necessary to realize the function of the low-pass filter 8 by software.

Further, a configuration in which output delay code specific signal Sfd and received signal S _RX to convert the waveform data into a computer at each A / D converter may be realized by software also function of the comparison unit 7 .. Further, the function of the delay unit 6 may be realized by software as a configuration in which the code specifying signal Sf and the received signal _SRX are each converted into waveform data by an A / D converter and output to a computer.

As an example, the output unit 10 is composed of a display device such as a display device or a light emitting diode, and executes a display operation as an output operation when the control signal Ss is output from the processing unit 9. In this example, as an example, in the case of a display device, the output unit 10 executes a display operation for displaying on the screen information indicating that the above signal collision has occurred in the transmission lines Lg and Lh. In the case of a light emitting diode, a display operation for lighting (continuous lighting operation or blinking operation) is executed. With this configuration, the signal reading system 1A can notify the user that the above-mentioned signal collision has occurred on the transmission lines Lg and Lh. The output unit 10 is not limited to the configuration in which the display device is used, and may be configured by a sound emitting device such as a buzzer or a speaker that emits a predetermined sound signal in the audible band.

Next, an example of using the signal reading system 1A and the operation of the signal reading system 1A at that time will be described with reference to the drawings.

First, as shown in FIG. 1, the probe PLa of the signal reading system 1A is connected to the covered wire La to be connected, the probe PLb is connected to the covered wire Lb to be connected, and the output connector. 4 is connected to an external analyzer. In the analysis device in this state, a terminal (not shown) corresponding to CANHigh on the analysis device side is connected to the transmission line Lg constituting the internal bus ISB via the output connector 4, and is not shown corresponding to CANLow on the analysis device side. Is connected to the transmission line Lh constituting the internal bus ISB via the output connector 4. In addition, the user operates the analysis device to take measures to stop the output of signals to the transmission lines Lg and Lh (internal bus ISB).

In this state, in the first detection unit 33 of the signal generation device 2A in the signal reading system 1A, the impedance element 33a is connected to the input terminal unit 31 and the covered lead wire La via the probe PLa as shown in FIG. Generates a voltage signal Vc1 in which the voltage changes according to the voltage Va (that is, it changes so that it becomes a low voltage when the voltage Va is the base voltage and becomes a high voltage when the voltage Va is a high voltage specified voltage). Then, the amplifier 33b non-invertings and amplifies the voltage signal Vc1 and outputs the voltage signal Vd1. As a result, the first detection unit 33 becomes a low voltage during the period during which the code Cs (“1”) constituting the CAN frame is transmitted to the serial bus SB, and the period during which the code Cs (“0”) is transmitted. The voltage signal Vd1 which becomes a high voltage is generated and output.

Further, in the second detection unit 34 of the signal generation device 2A, as shown in FIG. 2, the voltage of the impedance element 34a is changed according to the voltage Vb of the coated lead wire Lb connected via the input terminal unit 32 and the probe PLb. A variable (that is, a high voltage when the voltage Vb is the base voltage and a low voltage when the voltage Vb is the specified low voltage) is generated, and the amplifier 34b generates this voltage signal Vc2. The voltage signal Vc2 is non-inverting amplified and the voltage signal Vd2 is output. As a result, the second detection unit 34 becomes a high voltage during the period in which the code Cs (“1”) constituting the CAN frame is transmitted to the serial bus SB, and the period in which the code Cs (“0”) is transmitted. A low voltage signal Vd2 is generated and output.

Next, the signal generation unit 35A inputs the respective voltage signals Vd1 and Vd2, and generates and outputs the code identification signal Sf based on the difference voltage (Vd1-Vd2). In this case, since the probe PLa is connected to the coated lead wire La to be connected and the probe PLb is connected to the coated lead wire Lb to be connected, the signal generation unit 35A is connected to this covered lead wire Lb as shown in FIG. Based on the differential voltage (Vd1-Vd2), the high potential side voltage (recessive) is obtained during the period in which the code Cs (“1”) constituting the CAN frame (code string) is transmitted to the serial bus SB, and the code Cs ( A code identification signal Sf that becomes a low potential side voltage (dominant) during the period in which "0") is being transmitted is generated and output.

Subsequently, CAN driver 3 inputs the code specifying signal Sf, and outputs by converting the code specifying signal Sf to the transmission signal S _TX from a pair of output terminals transmission line Lg, the Lh. As described above, since the measures to stop the output of the transmission line Lg, signal to Lh is subjected to analysis apparatus, the transmission line Lg, the Lh only transmission signal S _TX is transmitted (i.e. , No signal collision occurred on the transmission lines Lg and Lh).

Thus, the analysis device is adapted to normally receive the transmission signal S _TX from a signal reading system 1A via the output connector 4, the transmission signal S _TX from a CAN frame being transmitted to the serial bus SB (the code sequence) Performs an analysis operation that reads and analyzes.

Further, in the signal reading system 1A, the CAN receiver 5 inputs the signal transmitted to the transmission lines Lg and Lh (in this case, the transmission signal _STX itself), converts it into the _{reception signal SRX, and outputs the signal.} To do. For this case, the received signal S _RX, although the voltage is a high potential in synchronism with the code specific signal Sf (recessive) and low potential (dominant), the phase of the code specific signal Sf phase, has a delayed signal by an equivalent time signal propagation delay time tdt and signal propagation delay time tdr total time _t ALL of the CAN receiver 5 (= tdt + tdr) and the CAN driver 3.

Next, the delay unit 6 inputs the code identification signal Sf and sets a preset delay time ( _{theoretical value of the total time t ALL} as described above, that is, each of the actual CAN driver 3 and CAN receiver 5). signal propagation delay time tdt, with approximately the same time) delayed by a total time _{t ALL} of tdr, and outputs it as a delay code specifying signal Sfd. Therefore, delay code specifying signal Sfd has a substantially uniform signal to the phase of the synchronized its voltage in the received signal S _RX high potential (recessive) and low potential (dominant), and and its phase received signal S _RX It has become.

Subsequently, the comparing unit 7 compares inputs the delay code specific signal Sfd and received signals S _RX, and outputs an output signal So indicating the result of the comparison. In this case, as described above, delay code specific signal Sfd and received signal S _RX is in a state whose phase is substantially uniform (i.e., at the same timing), the voltage from high potential (recessive) to a low potential (dominant) In addition, it is a signal that changes from low potential (dominant) to high potential (recessive) (that is, it is a signal whose logic matches throughout). Therefore, the comparison unit 7 continuously outputs an output signal So having a low potential. Note that this output signal So., noise and the logic of the above-mentioned delay code specifying signal Sfd and logic of the received signal S _RX is generated in the second case of the case of the two to be a mismatch (whisker-like pulse Signal) is normally generated.

Next, the low-pass filter 8 inputs the output signal So, removes the high-frequency component contained in the output signal So, and outputs the new output signal So1 to the processing unit 9. In this case, since the high frequency component contained in the output signal So is noise (whisker-shaped pulse signal) that can be removed as described above, the low-pass filter 8 removes this noise and uses it as the output signal So1. Output. As a result, the output signal So1 is a signal whose voltage is less than the above threshold voltage.

Subsequently, the processing unit 9 compares the voltage of the output signal So1 with the above threshold voltage while detecting the voltage, and when the detected voltage becomes equal to or higher than the above threshold voltage, the output signal So1 is used for specifying the delay code. detects that shows the results of a comparison between the logic of the received signal S _RX to the logic of the signal Sfd do not match, performing a notification operation. In this case, since the output signal So1 is a signal whose voltage is less than the above threshold voltage, the processing unit 9 does not execute the notification operation. Therefore, since the above control signal Ss is not output from the processing unit 9 to the output unit 10, the output unit 10 displays information indicating that a signal collision has occurred in the transmission lines Lg and Lh. Do not perform the display operation.

As a result, the user of the signal reading system 1A can send signals to the transmission lines Lg and Lh based on the display state of the output unit 10 (when the output unit 10 is configured by the sound emitting device, the sound emitting state). It is possible to confirm that measures have been taken for the analyzer to stop the output of.

Next, the operation of the signal reading system 1A when the user has not taken measures to stop the output of the signal to the transmission lines Lg and Lh (internal bus ISB) to the analysis device will be described. The same operation as the above operation when the measure for stopping the output of the signal to the transmission lines Lg and Lh is applied to the analysis device will be omitted.

Any signal reading system 1A in this case, CAN driver 3 inputs the code specifying signal Sf, transmission line Lg from a pair of output terminals and converts the code specifying signal Sf to the transmission signal S _TX, the Lh Output. However, since the analyzer has not taken measures to stop the output of the signal to the transmission lines Lg and Lh, the analyzer may output the signal to the transmission lines Lg and Lh. In this case, the transmission line Lg, the Lh, since the signal from the analyzer and the transmission signal S _TX from a signal reading system 1A is output, signal collision occurs in the transmission line Lg, Lh. As a result, the signal transmitted to the transmission lines Lg and Lh is not the original signal waveform transmission signal _STX (transmission signal _STX itself), but the signal waveform is distorted due to the influence of the signal from the analyzer. the (transmission signal _{S TX} different signal waveform from the original signal waveform) transmission signal _{S TX.}

Therefore, the CAN receiver 5 receives the signals transmitted to the transmission lines Lg and Lh, and the voltage is synchronized with the code identification signal Sf to be high potential (recessive) or low potential (dominant). Outputs _{the received signal SRX in a} state where it does not become. The comparison unit 7, by comparing to input delay code specific signal Sfd and the received signal S _RX, and outputs an output signal So indicating the result of the comparison. In this case, the output signal So., repetition wide pulse signal with the logic of the above-mentioned delay code specifying signal Sfd and logic of the received signal S _RX is generated when the first of the two cases as a mismatch included.

The low-pass filter 8 inputs the output signal So and outputs the output signal So1, but cannot remove the wide pulse signal included in the output signal So. Therefore, the output signal So1 includes this wide pulse signal in a state of the above threshold voltage or more. Therefore, the processing unit 9, the voltage of the output signal So1 that is detected becomes equal to or higher than said threshold voltage (i.e., the output signal So1 is the logic of the received signal S _RX to the logic of the delay code specifying signal Sfd match (It indicates the result of comparison with the non-existence) is detected, and the notification operation is executed. As a notification operation, the processing unit 9 outputs the above control signal Ss to the output unit 10 to display information indicating that a signal collision has occurred on the transmission lines Lg and Lh. Let 10 do it.

As a result, the user of the signal reading system 1A can use the signal on the transmission lines Lg and Lh based on the display state of the output unit 10 (when the output unit 10 is composed of the sound emitting device, the sound emitting state). It can be confirmed that a collision has occurred, that is, no measures have been taken for the analyzer to stop the output of signals to the transmission lines Lg and Lh. Therefore, the user can apply this measure to the analyzer.

As described above, according to the signal reading system 1A, the CAN receiver 5, the comparison unit 7, the processing unit 9, and the output unit 10 are provided, so that between the signal reading system 1A and the analysis device (specifically). Is that a signal collision occurs at a pair of output terminals (transmission lines Lg, Lh) of the CAN driver 3 to which the analyzer is connected, that is, a signal reading system 1A (specifically, signal reading). It is possible to notify the user that no measure has been taken for the analyzer to stop the output of the signal to the transmission lines Lg, Lh) of the system 1A. Therefore, the signal reading system 1A of the user is subjected respect analyzer measures the can be eliminated collision signals, thereby successfully sent a transmission signal S _TX from a signal reading system 1A to the analyzer Can be done. Further, this makes it possible for the analysis device to execute an analysis operation for normally reading and analyzing the CAN frame (code string) transmitted from the _{normal transmission signal STX to the serial bus SB.}

_{Further, in this signal reading system 1A, since the delay unit 6 is provided, the received signal SRX} is delayed with respect to the code identification signal Sf due to the signal propagation delay in the CAN driver 3 and the CAN receiver 5. At this time, the delay unit 6 can delay the code specifying signal Sf by the signal propagation delay and output it as the delayed code specifying signal Sfd. Accordingly, comparator 7 is substantially the phase of uniform and received signal S _RX and delay code specifying signal Sfd can be accurately compared, matched-mismatched logic each other when the collision of signals does not occur The output signal So indicating the above can be accurately output. Further, as a result, when the processing unit 9 indicates a mismatch based on the output signal So (specifically, the output signal So1) (that is, a signal collision occurs between the CAN driver 3 and the analysis device). When it occurs), the notification operation can be surely executed. Therefore, when a signal collision occurs between the CAN driver 3 and the analysis device, the user of the signal reading system 1A applies the above measures to the analysis device to eliminate the signal collision. The signal reading system 1A can cause the _{analysis device to normally transmit the transmission signal STX.}

As described above, the signal reading system 1A adopts a configuration including the delay unit 6, but the signal reading system 1A is not limited to this configuration. For example, the signal propagation delay in the CAN driver 3 and the CAN receiver 5 is extremely small, if negligible delay of the received signal S _RX for the code specifying signal Sf is omitted delay unit 6, the code in the comparator 7 enter a specific signal Sf and the received signal S _RX, the two signals Sf, by comparing the logic between the S _RX, to adopt a configuration to output an output signal so indicating the match or mismatch of the logic between that You can also.

Further, according to the signal reading system 1A, since the low-pass filter 8 is provided, the above noise included in the output signal So can be reliably removed and output to the processing unit 9 as the output signal So1. Therefore, according to the signal reading system 1A, it is possible to avoid the occurrence of a situation in which the processing unit 9 erroneously executes the notification operation due to this noise. Further, according to the signal reading system 1A, the delay unit 6 is composed of an RC type filter as shown in FIG. 3, the comparison unit 7 is composed of an EXOR circuit as shown in FIG. 1, and the low-pass filter 8 is described above. By configuring the processing unit 9 with such a known filter circuit and not including the computer as described above, the transmission lines Lg, Lh have a simple hardware-only configuration (software-free configuration). It is possible to detect that a signal collision has occurred and notify the user.

Further, according to the signal reading system 1A, since the output unit 10 is provided as described above, a display device for notifying the user that a signal collision has occurred in the transmission lines Lg and Lh is provided. It is possible to save the trouble of separately installing an output device such as a sound emitting device.

In the above-mentioned signal reading system 1A, an example of adopting a preferable configuration in which the output unit 10 is composed of a display device and a sound emitting device has been described, but the output unit 10 can also be configured by an external interface circuit. In this case, when the control signal Ss is input, the output unit 10 configured by the external interface circuit displays and emits sound to the display device and the sound emitting device arranged separately from the signal reading system 1A. Outputs a signal to execute the operation. Therefore, even in the signal reading system 1A adopting this configuration, although it takes time and effort to separately provide a display device and a sound emitting device, the same effect as the above signal reading system 1A in which the output unit 10 is composed of the display device and the sound emitting device. Can be played.

Further, as described above, when the processing unit 9 includes a computer, the low-pass filter 8 is configured to convert the output signal So into waveform data by the A / D converter and output it to the computer. Although the above functions can be realized by software, the processing unit 9 including the computer is configured by removing the above noise included in the output signal So with the low-pass filter 8 configured by hardware. The load on the computer can be reduced.

Further, in the above signal reading system 1A, the probe PLa in which the electrode portion 21a including the electrode 22a is arranged on the free end side and the probe PLb in which the electrode portion 21b including the electrode 22b is arranged on the free end side are input terminal portions. A configuration is adopted in which the signal generator 2A is connected to and used via the signals 31 and 32, but the configuration is not limited to this configuration. For example, although not shown, the signal generator 2A, the CAN driver 3, the output connector 4, the CAN receiver 5, the delay unit 6, the comparison unit 7, the low-pass filter 8, the processing unit 9, and the output unit 10 are not shown. A pair of pressing portions for pressing against the coated conductors La and Lb are formed in a part of the case. Further, electrodes 22a and 22b are arranged in the vicinity of each of the pressing portions in the case. Then, inside the case, the electrode 22a may be connected to the first detection unit 33, and the electrode 22b may be connected to the second detection unit 34. By adopting this configuration, the probes PLa and PLb can be omitted.

Further, the above-mentioned signal reading system 1A is for analyzing a CAN bus SB composed of a pair of covered lead wires La and Lb and a 2-wire differential voltage type logic signal Sa transmitted via the CAN bus SB. It was configured to be interposed between an analyzer (an analyzer configured to be connectable to a CAN bus SB composed of a pair of coated conductors La and Lb), but the signal reading system is limited to this configuration. It's not something. There is also a CAN bus composed of one covered lead wire, and there is also an analysis device that is connected to the CAN bus having this configuration and analyzes a logic signal transmitted to the CAN bus. Hereinafter, the signal reading system 1B used as an interposition between the CAN bus SB and the analysis device having this configuration will be described with reference to FIG. The same components as those of the signal reading system 1A are designated by the same reference numerals, and duplicate description will be omitted.

The signal reading system 1B as a signal reading system includes a single probe (for example, probe PLa), a signal generator 2B, a CAN driver 3, an output connector 4, a CAN receiver 5, a delay unit 6, a comparison unit 7, and a low-pass filter 8. , The processing unit 9 and the output unit 10 are provided. This signal reading system 1B has a CAN bus SB composed of one signal line (for example, one covered lead wire La) and a logic signal Sa (automobile body ground (signal)) transmitted via the CAN bus SB. It is interposed between the generator 2B and an analyzer for analyzing the voltage signal Va (voltage Va) transmitted to the coated lead wire La with reference to the reference potential portion (ground G)). The logic signal Sa is read (detected), a code identification signal Sf capable of specifying the code corresponding to the logic signal Sa is generated, and the code identification signal Sf is used as a transmission signal S that matches the input specifications of the analyzer. _It is converted into TX (single wire type logic signal conforming to the CAN communication protocol) and output to the analyzer.

As shown in FIG. 4, the signal generation device 2B includes an input terminal unit 31, a first detection unit 33, and a signal generation unit 35B. In this case, the signal generation unit 35B inputs the voltage signal Vd1 and generates and outputs the code identification signal Sf based on the voltage signal Vd1. In this case, when the probe PLa is connected to the covered wire La to which the probe PLa should be connected (correctly connected to the covered wire La), the signal generation unit 35B has a reference numeral shown in FIG. 2 based on the voltage signal Vd1. The specific signal Sf is correctly generated and output.

With the above configuration, as shown in FIG. 4, the signal generator 2B specifies the code shown in FIG. 2 as described above in a state where the probe PLa connected to the input terminal portion 31 is connected to the coated lead wire La. Signal Sf is correctly generated and output.

As shown in FIG. 4, the CAN driver 3 functions as a signal conversion device, inputs a code identification signal Sf, and uses the code identification signal Sf as a transmission signal conforming to the same CAN communication protocol as the logic signal Sa. It _{is converted to STX} (single wire type logic signal) and output from one output terminal.

The output connector 4 is composed of, for example, the same connector as the diagnostic connector connected to the single-wire CAN bus SB. Further, in the output connector 4, the pin 4a (one terminal) corresponding to the pin to which the voltage signal Va in the diagnostic connector is assigned has the same specifications as the CAN bus SB (for example, a resistance value equivalent to that of the CAN bus SB (for example, 60Ω). One of the pair of transmission lines Lg and Lh (internal bus ISB with the same characteristic impedance as the CAN bus SB) of the (specification in which the resistors 41 of) are connected to each other), the transmission line Lg (output terminal of the CAN driver 3). The pin 4b (other terminal) corresponding to the pin to which the ground is assigned in this diagnostic connector is connected to the transmission line Lh (the other terminal) of the pair of transmission lines Lg and Lh. It is connected to the transmission line connected to the ground G).

Therefore, for the sake of easy understanding, when the voltage of the voltage signal Vg is expressed as the voltage Vg (the voltage Vg has the same specifications as the voltage Va described above), the transmission signal _STX is the potential of the ground G. Is output from the CAN driver 3 to a pair of transmission lines Lg, Lh (internal bus ISB) as a non-differential voltage type signal represented by the voltage Vg, and further, an external analyzer is output from the output connector 4. Is output to.

In the CAN receiver 5, one input terminal is connected to one output terminal of the CAN driver 3 (which is also a transmission line Lg constituting the internal bus ISB), and a signal generated at this one output terminal (that is, a transmission line Lg) is generated. , Lh) is input, and is converted into a non-differential voltage type voltage signal (a signal having the same voltage level as the code identification signal Sf) and output as _{a received signal SRX.}

This signal reading system 1B also includes the CAN receiver 5, the comparison unit 7, the processing unit 9, and the output unit 10 in the same manner as the signal reading system 1A described above. A signal collision occurs between the signals (specifically, a pair of output terminals (transmission lines Lg, Lh) of the CAN driver 3 to which the analyzer is connected), that is, the signal reading system 1B (specifically). Can notify the user that no measure has been taken for the analyzer to stop the output of the signal to the transmission lines Lg, Lh) of the signal reading system 1B. Therefore, the signal reading system 1B of the user is subjected respect analyzer measures the can be eliminated collision signals, thereby successfully sent a transmission signal S _TX from a signal reading system 1B to the analyzer Can be done. Further, this makes it possible for the analysis device to execute an analysis operation for normally reading and analyzing the CAN frame (code string) transmitted from the _{normal transmission signal STX to the serial bus SB.}

Further, also in this signal reading system 1B, since the delay unit 6 is provided, the same effect as that of the signal reading system 1A provided with the delay unit 6 can be obtained. Also in the signal reading system 1B, is extremely small signal propagation delay in the CAN driver 3 and the CAN receiver 5, if a negligible delay of the received signal S _RX for the code specifying signal Sf is the signal described above reading system A configuration in which the delay portion 6 is omitted can be adopted in the same manner as in 1A.

Further, since the signal reading system 1B is also provided with the low-pass filter 8, the same effect as that of the signal reading system 1A provided with the low-pass filter 8 can be obtained. Further, also in this signal reading system 1B, since the output unit 10 is provided, the same effect as that of the signal reading system 1A provided with the output unit 10 can be obtained.

Further, in the above example, an analyzer (analyzer) is connected to the output connector 4 of the signal reading systems 1A and 1B as an example of a CAN communication compatible device, but the device connected to the output connector 4 is limited to the analysis device. Of course, other CAN communication compatible devices such as a data recording device may be connected.

1A, 1B signal reading system 2A, 2B signal generator
3 CAN driver
4 Output connector
5 CAN receiver
6 Delay part
7 Comparison section
8 low-pass filter
9 Processing unit 10 Output unit 22a, 22b Pair of electrodes 41 Resistance ISB Internal bus La, Lb Covered lead wire Lg, Lh Transmission line Sa Logic signal SB CAN bus Sf Code identification signal Sfd Delay code identification signal So, So1 Output signal S _RX reception signal S _TX transmission signal Va, Vb voltage (voltage transmitted to the signal line)

Claims (5)

A voltage transmitted to the coated conductor that is connected to an electrode arranged in a state close to the coated conductor that constitutes the CAN bus to transmit a logic signal conforming to the CAN communication protocol and is capacitively coupled to the electrode. A signal generator that generates a voltage signal whose voltage changes according to the voltage signal and generates a code identification signal that can specify a code corresponding to the logic signal based on the voltage signal.
A signal reading system including a CAN driver that converts the code identification signal into a transmission signal conforming to the same CAN communication protocol as the logic signal and outputs the signal from an output terminal to an external CAN communication compatible device.
A CAN receiver that receives the signal generated at the output terminal, converts it into a voltage signal, and outputs it as a received signal.
A comparison unit that inputs the code specifying signal and the received signal, compares the logic of the code specifying signal with the logic of the received signal, and outputs an output signal indicating match / mismatch between the logics. ,
A signal reading system including a processing unit that executes a notification operation when the output signal indicating the mismatch is input. A voltage transmitted to the coated conductor that is connected to an electrode arranged in a state close to the coated conductor that constitutes the CAN bus to transmit a logic signal conforming to the CAN communication protocol and is capacitively coupled to the electrode. A signal generator that generates a voltage signal whose voltage changes according to the voltage signal and generates a code identification signal that can specify a code corresponding to the logic signal based on the voltage signal.
A signal reading system including a CAN driver that converts the code identification signal into a transmission signal conforming to the same CAN communication protocol as the logic signal and outputs the signal from an output terminal to an external CAN communication compatible device.
A CAN receiver that receives the signal generated at the output terminal, converts it into a voltage signal, and outputs it as a received signal.
A delay unit that inputs the code identification signal and delays a time equivalent to the total time of each signal propagation delay time in the CAN driver and the CAN receiver and outputs the delay code identification signal.
Comparison in which the delay code specifying signal and the received signal are input, the logic of the delay code specifying signal is compared with the logic of the received signal, and an output signal indicating match / mismatch between the logics is output. Department and
A signal reading system including a processing unit that executes a notification operation when the output signal indicating the mismatch is input. The CAN bus is composed of a pair of the coated wires.
The signal generator is connected to the pair of electrodes arranged in close proximity to the pair of coated wires, and responds to a voltage transmitted to the pair of coated conductors that are capacitively coupled to the pair of electrodes. A pair of voltage signals whose voltage changes is generated, and a code identification signal is generated based on the pair of voltage signals.
The CAN driver outputs the transmission signal from the pair of output terminals.
The signal reading system according to claim 1 or 2, wherein the CAN receiver receives the signal generated in the pair of output terminals. A claim that includes a low-pass filter that is disposed between the comparison unit and the processing unit to remove high-frequency components contained in the output signal output from the comparison unit and output the high-frequency component to the processing unit. Item 4. The signal reading system according to any one of Items 1 to 3. Equipped with an output section
The signal reading system according to any one of claims 1 to 4, wherein the processing unit executes an operation of causing the output unit to output that the logics do not match each other as the notification operation.

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