JPWO2017109825A1 - Sensor connection disconnection detection method - Google Patents

Abstract

In a control / monitor signal transmission system in which a master station arranged on the control side and a plurality of slave stations arranged on the controlled side are connected by a common data signal line and data is transmitted by a transmission synchronization method, the bleeder current Provided is a sensor connection disconnection detection method that can be applied to a sensor that cannot detect the presence or absence of a connection disconnection by using. The protection means operates from the slave station via the input terminal to the sensor that is connected to the slave station and includes protection means that operates to protect the internal circuit when an overvoltage is applied to the input terminal that receives the detection signal. A test signal is output as a voltage, and the presence or absence of a disconnection between the slave station and the sensor is determined based on the presence or absence of a state change corresponding to the test signal of the test means provided in the slave station.
[Selection] Figure 1

Description

  The present invention reduces transmission of signal lines between a master station provided on the control side and a plurality of slave stations provided on the controlled side, connects them with a common data signal line, and synchronizes them with a transmission clock. The present invention relates to a method for detecting disconnection of a sensor connected to a slave station in a control / monitor signal transmission system that transmits data in a synchronous manner.

  In a system for centrally controlling a large number of devices arranged in a facility, so-called wiring-saving, which reduces the number of wirings, is widely implemented. As a general technique for reducing the wiring, a parallel signal and a serial signal are converted instead of a parallel connection in which each of a plurality of devices provided on the controlled side is directly connected to a control unit provided on the control side. A system in which a master station with multiple functions and a plurality of slave stations are connected to a control unit and a plurality of devices, respectively, and data is exchanged between the master station and a plurality of slave stations using a serial signal via a common data signal line Is widely adopted.

  When wiring saving is realized, in the state where many slave stations are connected, if the failure of the device arranged on the controlled side cannot be specified on the control unit side, the device far from the control side It is necessary to check each on-site, and it takes a lot of man-hours to identify the failure point.

  In view of this, the present applicant has disclosed, as a system for identifying, on the control side, a disconnection failure between a device (input unit and output unit) arranged on the controlled side and a slave station connected thereto, as disclosed in JP2011-114449A. Has proposed a remote wiring check system disclosed in Japanese Patent Publication No. Hokusho.

  In this remote wiring check system, in a control / monitor signal transmission system including a single control unit and a plurality of controlled devices, a connection between a master station and a slave station connected by a common data signal line with reduced wiring is possible. A management data area including connection data indicating a wiring state is provided, which is different from a control / monitor data area composed of control data (output data) and monitoring data (input data) transmitted simultaneously in both directions. In the connection data, short-circuit information, disconnection information, and normal information are identified. For this reason, it is possible to easily check the wiring connection state between the slave station itself, the slave station and the input unit, or between the slave station and the output unit without reducing the input data (monitoring data) capacity of the signal. In obtaining the short-circuit information and the disconnection information, a bleeder current is caused to flow between the output of the sensor signals to be detected, and the disconnection occurs when the total current including both the bleeder current and the sensor unit operating current is smaller than the first threshold value. And a method of determining a short circuit when the total current is greater than a second threshold is disclosed.

  Further, a method for discriminating between a short circuit and a disconnection by flowing a bleeder current has been proposed. For example, in Japanese Patent Laid-Open No. 3-176996, in an alarm circuit using a two-wire current output type proximity switch as a sensor, a leakage current constantly generated from a standby sensor, an operating current generated during operation of the sensor, and a short circuit are disclosed. There is disclosed an automatic line abnormality detection circuit that detects a circuit abnormality by introducing three types of short-circuit currents that are sometimes generated, or voltages induced by them, into respective detection circuits.

JP 2011-114449 A Japanese Patent Laid-Open No. 3-176996

  However, depending on the sensor, it may not be possible to detect the presence or absence of a disconnection using the bleeder current. For example, in a sensor that reduces the internal resistance of the circuit and saves power, the bleeder current is small, and it is difficult to detect a change in current and a change in voltage associated therewith.

  In addition, the ready-made products of the three-wire sensor flow a bleeder current to the output logic data output (ON / OFF data from the sensor) of the input signal line (hereinafter referred to as the input signal line) that receives the output signal from the sensor. is not. Therefore, when the output logic data from the sensor is OFF, no current flows through the input signal line from the sensor that transmits the output logic data, and it is difficult to detect a disconnection of the input signal line.

  Therefore, the present invention provides a control / monitoring signal transmission in which a master station arranged on the control side and a plurality of slave stations arranged on the controlled side are connected by a common data signal line, and data is transmitted by a transmission synchronization method. It is an object of the present invention to provide a sensor connection break detection method that can be applied to a sensor that cannot detect the presence or absence of a connection break using a bleeder current in the system.

  In the sensor connection disconnection detection method according to the present invention, an overvoltage is applied to an input terminal connected to a slave station that is connected to a master station via a common data signal line and transmits data by a transmission synchronization method, and the slave station receives a detection signal. An inspection signal is output from the slave station at a voltage at which the protection means operates via the input terminal to a sensor having protection means that operates to protect the internal circuit when the The presence / absence of a disconnection between the slave station and the sensor is determined based on the presence / absence of a state change corresponding to the inspection signal.

  The protection means is, for example, a Zener diode that connects the input signal line connected to the input terminal to the voltage reference line in parallel with the internal circuit of the sensor. This Zener diode prevents a current from flowing due to an applied voltage exceeding the rated voltage of the internal circuit and destroying the internal circuit.

  The slave station may output the inspection signal in a predetermined period from an arbitrary inspection start timing.

  The inspection start timing may be determined based on the timing at which the slave station reads the detection signal.

  The inspection start timing may be when a transmission period provided for information transmission from the slave station to the master station ends.

  The slave station and the sensor are connected by a power supply line, an input signal line, and a voltage reference line, and a voltage for outputting the inspection signal is applied as a pulse multiple times, and the inspection signal is output. Comparing the magnitude of the detection signal corresponding to the state of the inspection means and the magnitude of the detection signal corresponding to the state of the inspection means when the inspection signal is not output with a second threshold value smaller than the threshold value. Thus, it may be determined whether or not there is a disconnection between the power supply line and the voltage reference line.

  Based on the determination valid information indicating that the determination result is valid, a state in which the connection line is disconnected may be distinguished from a state in which the sensor is not connected to the slave station.

  The valid determination information may be included in a slave station information table in which information related to each of the plurality of slave stations held by the master station is aggregated.

  The determination valid information may be set by setting means provided in the slave station.

  The master station may detect the defect in the initial state by comparing the valid determination information transmitted from the slave station with information in the slave station information table.

  The master station may set the determination valid information for the slave station based on the slave station information table.

  The master station transmits, through the common data signal line, sensor presence confirmation information indicating that there is a sensor when there is no connection disconnection and that there is no sensor when there is a connection disconnection at a predetermined timing. Based on the data indicating the result of the determination, it may be acquired in correspondence with the address assigned to the sensor.

  According to the sensor disconnection detection method according to the present invention, the function of the protection means included in the sensor is used to protect the internal circuit of the sensor, and the inspection signal is transmitted via the input terminal of the slave station with the voltage at which the protection means operates. By outputting and determining whether or not there is a state change corresponding to the inspection signal of the inspection means provided in the slave station, it is possible to determine whether or not there is a disconnection without using a bleeder current. That is, the present invention can also be applied to a sensor that cannot detect the presence or absence of a disconnection using a bleeder current.

  Further, if the inspection signal is output for a predetermined period from an arbitrary inspection start timing, the time for applying stress to the protection means can be shortened, and sensor failure due to application of the inspection signal can be prevented. .

  The inspection start timing can be determined as appropriate according to the usage situation, and may be determined based on the timing at which the slave station reads the detection signal, for example.

  If the inspection start timing is when the transmission period provided for information transmission from the slave station to the master station ends, the inspection is performed once in one frame cycle in the transmission synchronization method. The accuracy of the inspection can be improved without waste for the transmission to the master station performed only once in the frame cycle.

  When the slave station and sensor are connected by the power supply line, input signal line, and voltage reference line, the inspection circuit outputs the inspection signal when the inspection signal is output multiple times as a pulsed voltage. The magnitude of the detection signal corresponding to the state of the detection signal and the magnitude of the detection signal corresponding to the state of the inspection circuit when the inspection signal is not output are smaller than a threshold for determining whether or not the input signal line is disconnected. By comparing with the second threshold value and determining the presence or absence of connection disconnection other than the input signal line, it becomes possible to identify the disconnection of the input signal line separately from other disconnections.

  In addition, by using the determination valid information indicating that the result of the determination of the presence / absence of the disconnection using the presence / absence of the state change of the inspection circuit of the slave station is valid, the sensor is disconnected in advance by using the determination valid information. It can be detected separately from the case where it is not.

  For example, the valid determination information may be included in a slave station information table in which the master station holds information on each of a plurality of slave stations. The slave station information table is created in advance before the sensor disconnection detection method is performed.

  On the other hand, the determination valid information may be set by a setting unit provided in the slave station. In this case, the connection status between the slave station and the sensor can be easily set while confirming on-site.

  Furthermore, when the master station holds the determination valid information, if the determination valid information is also set in the slave station, a defect in the initial state can be detected by comparing and collating both pieces of information.

  Furthermore, when the master station holds the determination valid information, the determination valid information can be set for the slave station as necessary.

  Furthermore, sensor presence confirmation information that the sensor exists when there is no connection breakage and the sensor does not exist when there is a connection breakage is transmitted via the common data signal line by the master station at a predetermined timing. The sensor connection status can be confirmed based on the sensor presence confirmation information as long as it is acquired in association with the address assigned to the sensor based on the data indicating the determination result.

It is a block diagram of the control and monitoring signal transmission system which implements the sensor connection disconnection detection method according to the present invention. It is a functional block diagram of a master station. It is a schematic diagram of the transmission procedure in a system. It is a time chart figure of a transmission signal. It is a functional block diagram of an input slave station. It is a functional block diagram which shows the connection state of a three-wire type sensor and a detection means. It is a time chart figure of a signal related to detection of disconnection of an input signal line. It is a functional block diagram which shows the connection state of a two-wire sensor and a detection means. It is a functional block diagram of an output slave station. It is a figure which shows a sensor presence confirmation information table.

  As an embodiment of the sensor connection disconnection detection method according to the present invention, an embodiment implemented in a control / monitor signal transmission system will be described.

  As shown in FIG. 1, the control / monitoring signal transmission system in which the sensor connection disconnection detection method according to the present invention is implemented includes a control unit 1 and common data signal lines DP and DN (hereinafter sometimes referred to as transmission lines). It is composed of a plurality of connected master stations 2 and an input / output slave station 4, an output slave station 6 and an input slave station 7 which are arranged on the controlled side and connected to the common data signal lines DP and DN. In FIG. 1, for convenience of illustration, each slave station is shown one by one, but there is no limitation on the type and number of slave stations connected to the common data signal lines DP and DN.

  The output unit 8 is, for example, an actuator, a (stepping) motor, a solenoid, a solenoid valve, a relay, a thyristor, or a lamp. The input unit 9 is, for example, a reed switch, a micro switch, a push button switch, a photoelectric switch, various sensors, or the like. It is. The sensor that is the detection target of the connection break corresponds to the input unit 9.

  The input / output slave station 4 is connected to a controlled device 5 including an output unit 8 and an input unit 9, the output slave station 6 is connected only to the output unit 8, and the input slave station 7 is connected only to the input unit 9. Has been. The output slave station 6 may include an output unit 8 (output unit integrated slave station 80), and the input slave station 7 includes an input unit 9 (input unit integrated slave station 90). It may be.

  The control unit 1 includes a management determination unit 11 having an arithmetic processing function and an input / output unit 12. The management judging means 11 receives data from the master station 2 via the input / output unit 12 and performs necessary arithmetic processing based on a program stored therein.

<Configuration of master station>
As shown in FIG. 2, the master station 2 includes an output data unit 21, a management data unit 22, a timing generation unit 23, a master station output unit 24, a master station input unit 25, and an input data unit 26. The control signal, which is connected to the common data signal lines DP and DN, is superimposed on the common data signal lines DP and DN, and is connected to the common data signal lines DP and DN. The monitoring data extracted from the monitoring signal superimposed on DP and DN is sent to the input / output unit 12 of the control unit 1.

  The output data unit 21 delivers the data received from the control unit 1 to the master station output unit 24 as serial data.

  The management data unit 22 includes storage means 29 having a nonvolatile function for storing the slave station information table. Based on the data received from the control unit 1 and the slave station information table, data necessary for specifying the slave station in the management control data area described later is transferred to the master station output unit 24 as serial data. Further, based on the determination valid information included in the slave station information table, the address information that is valid for the determination is delivered to the monitoring data extraction means 36.

  The slave station information table also designates the input / output slave station 4, the output slave station 6 or the input slave station 7 that causes the slave station side information not obtained as monitoring data to be output to the data signal lines DP and DN. Contains management control address data. In this embodiment, data obtained by adding a type identifier to the head address number which is the address data of the input / output slave station 4, the output slave station 6 and the input slave station 7 is used as the management control address data.

  The timing generation unit 23 includes an oscillation circuit (OSC) 31 and a timing generation unit 32. The timing generation unit 32 generates a timing clock of the system based on the oscillation circuit (OSC) 31, and generates a master station output unit 24, Delivered to the station input unit 25.

  The master station output unit 24 includes control data generating means 33 and a line driver 34. Based on the data received from the output data section 21 and the timing clock received from the timing generation section 23, the control data generation means 33 transmits a series of pulse signals to the common data signal lines DP and DN via the line driver 34. Superimpose the signal.

  As shown in FIG. 3, the transmission procedure is one frame cycle between the start signal ST of the transmission signal and the next start signal ST, followed by the control / monitoring data area and the management data area. It is composed of a series. The start signal ST is longer than the time width of the pulse signal and has a potential level higher than a threshold value Vst (18 V in this embodiment) for generating a transmission clock signal from the transmission signal.

  As shown in FIG. 4, the pulse signal constituting the transmission signal is composed of a potential level area (corresponding to a transmission clock signal, +24 V in this embodiment) higher than the threshold Vst and a potential level area lower than the threshold Vst. . In this embodiment, the potential level area higher than the threshold value Vst is the latter half of one cycle and the potential level area lower than the threshold value Vst is the first half of one cycle. May be reversed.

  The pulse width in the potential level area lower than the threshold value Vst represents the data of the control signal. The pulse width of the potential level area lower than the threshold value Vst constitutes a control data area as control data, and the control data area corresponds to the upper stage of the control / monitoring data area in FIG. .

  In this embodiment, when one period of the pulse signal constituting the transmission signal is t0, the pulse width (3/4) t0 of the pulse signal constituting the transmission signal represents the logical data “0”, and the pulse width (1 / 4) t0 represents logical data “1”. However, as long as it corresponds to the value of the control data input from the control unit 1, the length is not limited and may be determined appropriately.

  In the transmission data signal, the data of the monitoring signal is represented by whether the current superimposed on the potential level area lower than the threshold value Vst is larger or smaller than a predetermined value. The current value superimposed in the potential level area lower than the threshold value Vst constitutes a monitoring data area as monitoring data, and the monitoring data area is the control / monitoring data area in FIGS. 3 (a) and 3 (b). It corresponds to the lower row.

  In this embodiment, a current signal smaller than 10 mA represents logical data “0”, and a current signal larger than 10 mA represents logical data “1”.

  After the control / monitor data area, a management data area is provided as shown in FIGS. 3 (a) and 3 (b). 3 (a) and 3 (b), the upper part is an area where data is output from the master station 2 (hereinafter referred to as a management control data area), and the lower part is data is input to the master station 2. An area (hereinafter referred to as a management monitoring data area) is shown.

  In the management control data area, the first management control data ISTo that instructs the input / output slave station 4, the output slave station 6, and the input slave station 7 to request information, and the slave station address are designated. Two management control data IDXo are superimposed from the master station 2. In the management monitoring data area, the first management monitoring data STi corresponding to the first management control data ISTo from the input / output slave station 4, the output slave station 6 or the input slave station 7 specified by the second management control data IDXo. And the second management monitoring data IDXi are superimposed.

  The master station input unit 25 includes a monitoring signal detection unit 35 and a monitoring data extraction unit 36. The monitoring signal detection means 35 detects the monitoring signal superimposed on the common data signal lines DP and DN from the input / output slave station 4, the output slave station 6 or the input slave station 7.

  As described above, the data of the monitoring signal is represented by whether the current superimposed on the potential level lower than the threshold value Vst is larger or smaller than 10 mA, and after the start signal ST is transmitted, the input / output slave station 4 The monitoring signal is received from each of the output slave station 6 and the input slave station 7. Then, the monitoring signal detected by the monitoring signal detection unit 35 is delivered to the monitoring data extraction unit 36.

  The monitoring data extraction unit 36 extracts the monitoring data and the management monitoring data in synchronization with the timing from the timing generation unit 32 and outputs it to the input data unit 26 as serial input data. At this time, only the monitoring data indicating whether or not the disconnection is valid is output by the masking process based on the valid address information passed from the management data unit 22.

  The input data unit 26 converts the serial input data received from the monitoring data extraction unit 36 into parallel data, and sends it to the input / output unit 12 of the control unit 1 as monitoring data and management monitoring data.

<Configuration of input slave station>
As shown in FIG. 5, the input slave station 7 includes a transmission receiving means 41, management control data extracting means 42, address extracting means 43, address setting means 44, management monitoring data transmitting means 45, input means 46, monitoring data transmitting means. 47 and a slave station input unit 70 having a disconnection determination means 48. Also, a line receiver 71 and a line driver 72 arranged between the slave station input unit 70 and the common data signal lines DP and DN, a power source 73 that generates internal circuit power from the transmission signal, the slave station input unit 70 and the input unit 9 Inspection means 50 disposed between the two.

  The input slave station 7 of this embodiment includes an MCU that is a microcomputer control unit as an internal circuit, and this MCU functions as the slave station input unit 70.

  Calculations and storages required for the processing are executed using the CPU, RAM, and ROM provided in this MCU (hereinafter referred to as MCU 70), and each processing of each of the above-mentioned means constituting the slave station input unit 70 is performed. The relationship between the CPU, the RAM, and the ROM in FIG.

  The transmission receiving means 41 receives the transmission signal transmitted to the common data signal lines DP and DN via the slave station line receiver 71, and receives this via the management control data extraction means 42, the address extraction means 43 and the management monitoring data transmission means. Deliver to 45.

  The management control data extracting means 42 transmits the management control signal data (management control data) for the address that matches the management control address obtained by adding the identifier of the own station type to the own station address set by the address setting means 44. Is extracted from the management data area of the pulse signal that constitutes. The extracted management control data is delivered to a processing unit that executes processing based on the data. However, in this embodiment, the management control data is not used for sensor connection disconnection detection, and therefore, illustration and description of the output destination of the management control data are omitted.

  The address extracting means 43 counts the pulse signals constituting the transmission signal starting from the start signal ST indicating the start of the transmission signal. The timing at which the count value coincides with the local station address data set by the address setting means 44 is the timing at which the monitoring data area assigned to the local station of the transmission signal starts. Also, since the monitoring data area is composed of a plurality of transmission signal pulses, and the number of transmission signal pulses is predetermined, by obtaining the timing at which the monitoring data area allocated to the own station starts, It is also possible to obtain the timing at which the monitoring data area assigned to the station ends. Then, the address extracting means 43 validates the monitoring data transmitting means 45 at the timing when the monitoring data area assigned to the own station starts. Also, an inspection start timing signal is output to the inspection means 50 at the timing when the monitoring data area assigned to the own station ends.

  The management monitoring data transmission means 45 counts the pulse signals constituting the transmission signal starting from the start signal ST of the transmission signal, and obtains the timing of the management data area. Then, a management monitoring signal is output to the common data signal lines DP and DN via the slave station line driver 54. However, when the sensor connection disconnection detection data transmitted using the monitoring data area in this embodiment is transmitted using the management monitoring data area, as shown by the broken line in FIG. Data relating to connection disconnection detection is transferred from the disconnection determination means 48 to the management monitoring data transmission means 45.

  The input unit 46 delivers data based on the input from the disconnection detection unit 50 to the monitoring data transmission unit 44.

  When the monitoring data transmission means 47 is validated by the address extraction means 43, the data delivered from the input means 46 and the disconnection judgment means 48 are sent to the common data signal lines DP and DN via the slave station line driver 72. Output as a monitoring signal. The monitoring signal is superimposed on the monitoring data area of the transmission procedure (data M1 and M2 of the transmission signal assigned to the own station in FIG. 3B).

  The disconnection determination means 48 determines the presence or absence of a connection disconnection based on the input from the inspection means 50, and corresponds to the data (2 in FIG. 3B) of the transmission signal assigned to the own station in the data indicating the determination result. Data) to the monitoring data transmission means 47. The determination procedure will be described later.

<Configuration of inspection means>
The inspection unit 50 is connected to the input unit 9 and includes a current detection unit 52 and an inspection power source 53 as shown in FIG.

  The input unit 9 is a sensor that is a detection target of connection disconnection, includes a detection unit 97, and is connected to the disconnection detection unit 50 of the slave station 7 through the power line 91, the input signal line 92, and the voltage reference line 93. ing. In the following description, the input unit 9 is a sensor 9.

  The detection means 97 is connected to the power supply line 91 and the voltage reference line 93, operates with power supplied from the power supply 73, and outputs a signal corresponding to the detection state. The type of the detection unit 97 is not limited as long as it can detect the detection target, and a type of sensor according to the use situation and purpose such as an optical sensor, a proximity sensor, and a magnetic sensor can be adopted.

  The output signal line of the detection means 97 is connected to the base of a transistor 94 that opens and closes the input signal line 92 and the voltage reference line 93. The transistor 94 is opened and closed according to the detection state of the detection unit 97, whereby the voltage of the input signal line 92 with respect to the voltage reference line 93 changes according to the detection state of the detection unit 97. That is, the change in the detection state in the detection means 97 is reflected in the change in the state of the input signal line 92.

  A Zener diode 95 is connected in parallel between the collector and emitter of the transistor 94. The Zener diode 95 corresponds to the protection means of the present invention, and functions as a bypass path of the transistor 94, thereby preventing breakdown due to an applied voltage exceeding the rated voltage to the transistor 94. Further, a backflow prevention diode 96 is connected in series to the transistor 94 on the collector side (input signal line 92 side) of the transistor 94 to prevent breakdown of the transistor 94 and the Zener diode 95 due to backflow current.

  A voltage signal based on the potential difference of the input signal line 92 with respect to the voltage reference line 93 corresponds to the detection signal of the present invention, and is input to the slave station input / output unit 70 via the inspection means 50. As shown in FIG. 7, when the detection means 97 detects a detection target and the output from the detection means 97 (detection means output) is turned ON, a potential difference between the input signal line 92 and the voltage reference line 93 is generated and input. A current flows through the signal line 92. A detection signal based on the potential difference is input to the slave station input / output unit 70.

  The current detection unit 52 includes a test resistor 55 inserted in series with the voltage reference line 93 and a comparator 56 that detects a potential difference generated in the test resistor 55. Then, a detection signal d corresponding to the detection result of the comparator 56 is output to the input means 46 of the input / output unit 70. The output of the detection signal d corresponds to a state change corresponding to the inspection signal of the inspection means 50 of the present invention.

  When receiving the inspection start timing signal from the slave station input / output unit 70, the inspection power supply 53 applies a pulsed inspection voltage to the input signal line 92 for a predetermined period. That is, the slave station 7 outputs a test signal at a voltage at which the Zener diode 95 as the protection means operates via an input terminal that receives the detection signal. A protective resistor 54 that suppresses the current flowing through the Zener diode 95 to be smaller than the maximum rated current of the Zener diode 95 is inserted into the output line of the inspection power supply 53.

  When a pulsed inspection voltage is applied to the input signal line 92, when the sensor 9 and the input slave station 7 are normally connected, the input signal line 92 reaches the voltage reference line 93 via the Zener diode 95. A pulsed inspection current i flows through the path. On the other hand, when the input signal line 92 is disconnected, the pulsed inspection current i does not flow.

  Therefore, when a pulsed inspection current i flows when a pulsed inspection voltage is applied, it can be determined that the input signal line 92 is connected. On the other hand, if the pulsed inspection current i is not flowing when the pulsed inspection voltage is applied, it can be determined that the input signal line 92 is disconnected.

  When the inspection current i flows, the value of the detection signal d (potential difference between both ends of the inspection resistor 55) input from the current detection unit 52 to the input / output unit 70 changes corresponding to the inspection current i. In the embodiment, the disconnection determination means 48 of the input / output unit 70 determines whether or not the input signal line 92 is disconnected based on data obtained by A / D conversion. That is, as shown in FIG. 7, when the detection signal d is equal to or greater than the threshold da, the input signal line 92 is in a connected state, and when the detection signal d is smaller than the threshold da, it is determined that the input signal line 92 is disconnected. To do.

  Further, since the inspection current i is a combination of the current due to the pulsed inspection voltage and the standby current due to the power supply voltage of the power source 73, it flows even when the input signal line 92 is disconnected. There is. Therefore, when the detection signal d when the pulsed inspection voltage is applied is smaller than the threshold da, the presence or absence of other connection disconnection is determined by comparison with the second threshold db smaller than the threshold da. The disconnection of the input signal line 92 is specified separately from other disconnections.

  As shown in FIG. 7, the detection signal d when the pulsed inspection voltage is applied is greater than or equal to the second threshold value db, and the detection signal d when the pulsed inspection voltage is not applied is the second threshold value db. Is smaller than the threshold value db, it is determined that there is no connection disconnection of the input signal line 92 and that there is a connection disconnection of the power supply line 91 and the voltage reference line 93.

  Further, when the detection signal d when the pulsed inspection voltage is applied is smaller than the second threshold value db, it is determined that there is a disconnection of two or more lines.

  In the known sensor, the rated voltage of the Zener diode 95 that protects the transistor 94 that opens and closes the input signal line 92 and the voltage reference line 93 is less than the maximum rated voltage of the transistor 94 and about 1.5 times the sensor rating. Designed with.

  In this embodiment, a voltage of 50 V, which is sufficiently higher than the rated voltage of the Zener diode 95, is output from the output line of the inspection power supply 53 to the input signal line 92 via the protective resistor 54.

  However, the voltage specification of the Zener diode 95 varies depending on the specification of the sensor 9 (12V specification, 24V specification, etc.). Therefore, the inspection voltage of the inspection power supply 53 is changed according to the output of the input / output unit 70.

  Since the inspection current i is a very small current, it may not be detected due to the influence of electrical signals, noise, transmission noise, etc. in the surrounding environment. Therefore, a pulsed inspection voltage is applied a plurality of times during a predetermined period. What is necessary is just to set the frequency which applies a pulse-shaped test | inspection voltage suitably according to a use environment. For example, a pulsed inspection voltage having a width of 50 μsec can be applied a predetermined number of times every 100 msec.

  At this time, the disconnection determination means 48 of the slave station input / output unit 70 determines that the connection state is established if the detection signal d that is equal to or greater than the threshold value continues for a predetermined number of times. to decide.

  As shown in FIG. 7, the inspection voltage is applied only during the inspection period Td from the inspection start timing ts to the inspection end timing te. Then, by shortening the time for applying stress to the Zener diode 95, failure of the sensor 9 due to application of the inspection signal is prevented.

  Further, the inspection period Td is a monitoring data area assigned to the own station in the transmission signal, that is, after the transmission period Tt provided for information transmission from the input slave station 7 to the master station 2, Since transmission to the master station 2 that is necessarily inspected in one frame cycle is performed only once in one frame cycle, it is sufficient that the inspection is performed once in one frame cycle. Therefore, the accuracy of inspection can be improved without waste.

  In this embodiment, the inspection start timing is set when the transmission period provided for information transmission from the input slave station 7 to the master station 2 ends. An appropriate timing may be set according to the above. For example, the timing may be determined based on the timing at which the input slave station 7 reads the detection signal (read timing). However, it is appropriate that the inspection frequency is once in one frame cycle.

<Connection of two-wire sensor>
The sensor 9 may be a two-wire type. FIG. 8 shows a connection state between the two-wire sensor and the detection means. In FIG. 8, the same parts as those of the input slave station 7 and the sensor 9 shown in FIGS. 5 and 6 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  Also in the sensor 9a shown in FIG. 8, as in the sensor 9 shown in FIG. 6, the voltage signal based on the potential difference between the input signal line 92 and the voltage reference line 93 corresponds to the detection signal of the present invention. Is input. The sensor 9a is a proximity sensor. When the detection target approaches, the detection current ic flows, and the circuit current ia in the sensor becomes the total value ib + ic of the minute current ib and the detection current ic of the internal circuit. That is, the potential difference of the input signal line 92 with respect to the voltage reference line 93 differs between when detected and when not detected, and a detection signal based on this potential difference is input to the slave station input unit 70.

<Configuration of output slave station>
As shown in FIG. 9, the output slave station 6 includes a transmission receiving means 41, management control data extracting means 42, address extracting means 43, address setting means 44, management monitoring data transmitting means 45, control data extracting means 61 and output means. A slave station output unit 60 having 62 is provided.

  Similarly to the input slave station 7, the output slave station 6 also includes an MCU that is a microcomputer control unit as an internal circuit, and this MCU functions as the slave station output unit 60. Similar to the MCU 70, calculations and storages necessary for processing of the output slave station 6 are executed using the CPU, RAM, and ROM provided in this MCU.

  Calculations and storages necessary for the processing are executed using the CPU, RAM, and ROM provided in this MCU (hereinafter referred to as MCU 60), but each processing of each of the above-mentioned means constituting the slave station output unit 60. The relationship between the CPU, the RAM, and the ROM in FIG. In FIG. 9, the same reference numerals are given to substantially the same parts as those of the input slave station 7, and the description thereof is simplified or omitted.

  The address extracting means 43 of the output slave station 6 counts the pulse signals constituting the transmission signal starting from the start signal ST indicating the start of the transmission signal, and the count value is set by the own station address setting means 44 A timing signal for extracting control data is delivered to the control data extracting means 61 at a timing that coincides with the address data.

  The control data extraction unit 61 transmits the control data transmitted to the local station address set in the local station address setting unit 44 from the timing signal delivered from the address extraction unit 43 and the transmission transmission signal delivered from the transmission reception unit 41. A value is extracted and delivered to the output means 62.

  The output unit 62 outputs information based on the control data delivered from the address extraction unit 43 to the output unit 8 to operate or stop the output unit 8.

<Configuration of I / O slave station>
Both the output unit 8 and the input unit 9 that are in a corresponding relationship are connected to the input / output slave station 4. Similarly to the output slave station 6 and the input slave station 7, the input / output slave station 4 includes an MCU that is a microcomputer control unit as an internal circuit, and this MCU functions as a slave station input / output unit. It has become. Similar to the MCU 60 and the MCU 70, calculations and storages necessary for the processing of the input / output slave station 4 are executed using the CPU, RAM, and ROM included in the MCU.

  Calculations and storages required for the processing are executed using the CPU, RAM and ROM provided in this MCU. The CPU, RAM and ROM in the processing of each of the above means constituting the slave station input / output unit The relationship is omitted for convenience of explanation. The slave station input / output unit includes both the slave station input unit 70 and the slave station output unit 60. These components are substantially the same as the slave station input unit 70 and the slave station output unit 60. Since it is the same, illustration is abbreviate | omitted.

  The determination valid information is included in the slave station information table stored in the management data unit 22 of the master station 2 in the above embodiment, but may be set in each of the input slave stations 7. In this case, it is assumed that the input slave station 7 has a function for setting determination valid information. For example, the slave station input unit 70 may have a wireless communication function, a storage area for determination valid information may be provided, and the determination valid information may be input wirelessly using a terminal device separate from the input slave station 7. When the determination valid information is set only in the input slave station 7, the information can be transmitted to the master station 2 using the management monitoring data area.

<Sensor presence check>
The master station 2 acquires sensor presence confirmation information in association with the address assigned to the sensor based on data indicating the determination result transmitted via the common data signal lines DP and DN at a predetermined timing. . The sensor presence confirmation information is information indicating that a sensor exists when there is no connection disconnection, and that no sensor exists when there is a connection disconnection. An example is shown in FIG.

  In this embodiment, the input slave station 7 to which the monitoring data areas IN1, IN2, IN3, and IN4 shown in FIG. 3 are assigned has one terminal for connecting the sensor 9. Therefore, the head addresses # ad1, # ad2, # ad3, and # ad4 of the monitoring data areas IN1, IN2, IN3, and IN4 are addresses assigned to the sensors, respectively.

  In this embodiment, the data M2 indicating the result of the determination of whether or not there is a sensor connection disconnection indicates that the logical data “1” indicates that there is no connection disconnection and the logical data “0” indicates that there is a connection disconnection. Therefore, when the data M2 in the monitoring data areas IN1, IN2, IN3, and IN4 are “1”, “0”, “1”, and “1”, respectively, as shown in FIG. 10, the sensor address # ad1 , # Ad2, # ad3, and # ad4 are “1”, “0”, “1”, and “1”, respectively.

  That is, the sensor 9 is not connected to the input slave station 7 corresponding to the sensor address # ad2, and the sensor is connected to the input slave station 7 corresponding to the sensor addresses # ad1, # ad3, and # ad4. Will be shown. Therefore, the sensor connection status can be confirmed based on the sensor presence confirmation information.

  In this embodiment, the sensor acquisition confirmation information is acquired when the cycle of the second frame is transmitted after the start of the system. However, the timing is not limited, and is determined as appropriate according to the use situation or the like. be able to.

1 Control Unit 2 Master Station 4 I / O Slave Station 6 Output Slave Station 7 Input Slave Station 8 Output Unit 9 Input Unit (Sensor)
9a sensor 11 management judging means 12 input / output unit 21 output data part 22 management data part 23 timing generating part 24 master station output part 25 master station input part 26 input data part 29 storage means 31 oscillation circuit (OSC)
32 timing generation means 33 control data generation means 34 line driver 35 monitoring signal detection means 36 monitoring data extraction means 41 transmission reception means 42 management control data extraction means 43 address extraction means 44 address setting means 45 management monitoring data transmission means 46 input means 47 Monitoring data transmission means 48 Disconnection determination means 50 Inspection means 52 Current detection section 53 Inspection power supply 54 Protection resistance 55 Inspection resistance 56 Comparator 60 Slave station output section 61 Control data extraction means 62 Output means 70 Slave station input section 71 Line receiver 72 Line driver 73 Power supply 91 Power supply line 92 Input signal line 93 Voltage reference line 94 Transistor 95 Zener diode 97 Detection means d Detection signal i Inspection current ia Circuit current ib Minute current ic Detection current

The slave station and the sensor are connected by a power supply line, an input signal line, and a voltage reference line, and a voltage for outputting the inspection signal is applied as a pulse multiple times, and the inspection signal is output. By comparing the magnitude of the detection signal corresponding to the state of the inspection means and the magnitude of the detection signal corresponding to the state of the inspection means when the inspection signal is not output with a threshold value , the power line and the The presence or absence of disconnection of the voltage reference line may be determined.

The master station extracts the monitoring data indicating the presence or absence of disconnection from the monitoring signal transmitted from the slave station based on the determination valid information indicating that the result of the determination is valid, and the determination is valid Only things may be output .

The slave station may transmit the determination valid information to the master station .

Claims (11)

  Connected to the master station via a common data signal line and connected to a slave station that transmits data using the transmission synchronization method. The slave station operates to protect the internal circuit when an overvoltage is applied to the input terminal that receives the detection signal. An inspection signal is output from the slave station to the sensor provided with the protection means using a voltage at which the protection means operates via the input terminal, and depending on whether there is a state change corresponding to the inspection signal of the inspection means provided in the slave station A sensor connection break detection method, comprising: determining whether or not there is a connection break between the slave station and the sensor.   The sensor connection disconnection detection method according to claim 1, wherein the slave station outputs the inspection signal for a predetermined period from an arbitrary inspection start timing.   The sensor connection disconnection detection method according to claim 2, wherein the inspection start timing is determined based on a timing at which the slave station reads the detection signal.   The sensor connection break detection method according to claim 2 or 3, wherein the inspection start timing is when a transmission period provided for information transmission from the slave station to the master station ends.   The slave station and the sensor are connected by a power supply line, an input signal line, and a voltage reference line, and a voltage for outputting the inspection signal is applied as a pulse multiple times, and the inspection signal is output. Comparing the magnitude of the detection signal corresponding to the state of the inspection means and the magnitude of the detection signal corresponding to the state of the inspection means when the inspection signal is not output with a second threshold value smaller than the threshold value. 5. The sensor connection disconnection detection method according to claim 1, wherein the presence or absence of connection disconnection between the power supply line and the voltage reference line is determined.   6. The method according to any one of claims 1 to 5, wherein a state in which the connection line is disconnected is distinguished from a state in which the sensor is not connected to the slave station based on determination validity information indicating that the determination result is valid. The sensor connection disconnection detection method of crab.   The sensor connection disconnection detection method according to claim 6, wherein the determination valid information is included in a slave station information table that is stored in the master station and aggregates information related to each of the plurality of slave stations.   The sensor connection disconnection detection method according to claim 6 or 7, wherein the determination valid information is set by a setting unit included in the slave station.   9. The sensor connection break detection method according to claim 8, wherein the master station compares the determination valid information transmitted from the slave station with information in the slave station information table to detect a failure in an initial state.   The sensor connection break detection method according to claim 7, wherein the master station sets the determination valid information for the slave station based on the slave station information table.   The master station transmits, through the common data signal line, sensor presence confirmation information indicating that there is a sensor when there is no connection disconnection and that there is no sensor when there is a connection disconnection at a predetermined timing. The sensor connection disconnection detection method according to any one of claims 1 to 10, wherein the sensor connection disconnection detection method is acquired in association with an address assigned to the sensor based on data indicating the result of the determination.

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