JP5085811B1 - Disconnection detection method and slave station terminal used for that method - Google Patents

Abstract

In a control / monitor signal transmission system in which data is transmitted by a transmission synchronization method, a disconnection detection method capable of easily detecting the presence or absence of disconnection of an input signal line of an input unit which is a three-wire sensor, and its Provide a slave station terminal to be used for the system.
A slave station corresponding to an input unit provides a time band for turning on or off the load resistance of the input unit while the input signal line of the input unit is normally connected, and turns on the load resistance. Output logic data from the input unit in the presence / absence of the detection target and in the state without the detection target obtained in the selected time zone, and the internal by the operation of the input unit obtained in the time zone when the load resistance is turned off Based on the detection target object logic data corresponding to the change in the consumption current, it is determined whether the connection state of the input unit is normal or abnormal, and the connection unit abnormal state or the input unit in the management data area of the transmission signal A signal constituting data indicating a normal connection state is superimposed.
[Selection] Figure 1

Description

  The present invention reduces the number of signal lines between a master station connected to a control unit and a plurality of output units and input units, or a plurality of slave stations corresponding to a plurality of controlled devices, and connects them with a common data signal line. In a control / monitor signal transmission system that transmits data using a transmission synchronization method such as synchronizing with a transmission clock, the present invention relates to a disconnection detection method for detecting a disconnection of an input signal line of an input unit and a slave station terminal used for the method. Is. The output unit operates in accordance with an instruction from the control unit, and an actuator, a (stepping) motor, a solenoid, a solenoid valve, a relay, a thyristor, and the like correspond to this. On the other hand, the input unit transmits information related to the output unit to the control unit, and a reed switch, a micro switch, a push button switch, a photoelectric switch, various sensors, and the like correspond to this. In addition, the controlled device is a device composed of an output unit and an input unit.

  In a control system including a control unit, a plurality of output units and input units, or a plurality of controlled devices, 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 used instead of a parallel connection that directly connects a plurality of output units and input units or signal lines extending from a controlled device to the control unit. The master station and the plurality of slave stations having the conversion function are connected to the control unit, the plurality of output units and the input unit, or the plurality of controlled devices, respectively, and common data between the master station and the plurality of slave stations. A method of exchanging data with a serial signal via a signal line is widely adopted.

  When wiring saving is realized, when a failure of the output unit, input unit, or controlled device cannot be specified on the control unit side in a state where a large number of slave stations are connected, move away from the control unit. It is necessary to check each output unit, input unit, or controlled device, and it takes a lot of man-hours to identify the failed part.

  Therefore, the present applicant has proposed a remote wiring check system disclosed in Japanese Patent Application Laid-Open No. 2011-114449 as a system for identifying a disconnection failure between a slave station and an input unit and an output unit on the control unit side. ing. 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

  In a three-wire sensor, the presence or absence of a short circuit or disconnection of a power supply line can be detected relatively easily by using a standby current. However, the disconnection of the input signal line cannot be easily detected. For example, when the output logic data from the sensor (ON / OFF data from the sensor) is OFF, no current flows through the input signal line from the sensor that transmits the output logic data, so the input signal line is disconnected. Cannot be easily detected. When a three-wire sensor is used as an input unit, in order to detect the presence or absence of disconnection of the input signal line from the input unit, it is necessary to pass a bleeder current between the input signal lines outside the input unit side. However, since most of the existing three-wire sensors are not designed to allow bleeder current to flow through the output logic data output, it is necessary to devise a method to consciously flow bleeder current between input signal lines outside the input section. It was. For this reason, when a three-wire sensor is used as an input unit, it has not been possible to easily determine whether or not the input signal line is disconnected.

  Therefore, the present invention provides a master station connected to the control unit and a plurality of output units, an input unit, and a plurality of slave stations corresponding to the controlled devices are connected by a common data signal line, and data transmission is performed by a transmission synchronization method. In a control / monitoring signal transmission system to be performed, a disconnection detection method capable of easily detecting the presence or absence of disconnection of an input signal line of an input unit which is a three-wire sensor, and a slave station terminal used for the method With the goal.

  The disconnection detection method according to the present invention is a control / monitoring signal transmission system in which a master station and a plurality of slave stations are connected by a common data signal line, and data is transmitted by a transmission synchronization method, and transmitted to the common data signal line. The transmission signal to be transmitted is provided with a management data area different from the control / monitor data area composed of the control signal data and the monitor signal data. Then, the slave station corresponding to the input unit provided a time band for turning on or off the load resistance of the input unit while the input signal line of the input unit was normally connected, and turned on the load resistance. Output logic data from the input unit in the state with the detection target and without the detection target obtained in the time zone, and internal consumption by the operation of the input unit obtained in the time zone when the load resistance is turned off Based on the detection target object logic data corresponding to the change in current, it is determined whether the connection state of the input unit is normal or abnormal, and the connection data abnormal state or normal connection state of the input unit in the management data area A signal constituting data indicating is superimposed.

  When the detection target object logical data is in the presence / absence of the detection target object, the indicator lamp (LED etc.) is turned ON / OFF as the operation display of the input unit, and the input unit at that time It is obtained by detecting two values of the internal current consumption (i0d, i0u shown in FIG. 7) of the input section obtained through the ground side connection. The present invention focuses on detecting the change in only the internal current consumption of the input unit and determining the presence or absence of the detection target object. However, when the output logic data from the input section is ON (load resistance is ON), the internal consumption current of the input section cannot be detected via the ground side connection due to the influence of the load current flowing through the load resistance. Therefore, in order to detect the internal current consumption of the input unit, it is necessary to provide a time band for turning off the load resistance.

  As a synchronization method of the transmission synchronization method of the control / monitor signal transmission system to which the failure detection method according to the present invention is applied, for example, a method using a transmission clock generated by the timing generation means of the master station is suitable. . In this case, under the control of the transmission clock, the master station outputs a series of pulse signals as a control signal to the common data signal line according to the value of the control data delivered from the control unit, The data value of the monitoring signal superimposed on the signal for each cycle of the clock from each of the plurality of slave stations is extracted and transferred to the control unit. On the other hand, each of the plurality of slave stations counts the pulses of the series of pulse signals starting from the start signal indicating the start of the series of pulse signals, and when the count value matches the own station address, Data corresponding to the local station is extracted from the pulse signal, and the monitoring signal is superimposed on a series of pulse signals in the same pulse cycle as the clock from which the data corresponding to the local station is extracted, or the count value is When it matches the station address, data corresponding to the own station is extracted from the series of pulse signals or the monitoring signal is superimposed on the series of pulse signals. However, the synchronization method is not limited, and a method suitable for the system design condition may be adopted.

  For each of the output logic data and the detection target object logic data, a threshold value is set for distinguishing between the state with the detection target and the state without the detection target, and the detection from the state with the detection target For each of the output logic data and the detection object logic data, the presence / absence of a change to a state without an object or the presence / absence of a change from a state without the detection object to a state with the detection object is obtained. When the detection object logical data changes and the output logical data does not change, or when the detection object logical data does not change and the output logical data changes, the connection state is abnormal. It may be determined.

  The output logic data and the detected object logical data are temporary data obtained at a predetermined timing, and the slave station includes storage means for the output logical data and the detected object logical data. There may be.

  The management data area includes a management control data area in which data from the master station is superimposed and a management monitoring data area in which data from the slave station is superimposed, and the management monitoring data area from the slave station May be determined as data disconnection of the common data signal line when the data extracted from the management monitoring data area in the master station is “0”.

  The slave station may switch and superimpose a signal constituting the detected object logical data and a signal constituting other monitoring data in the management data area.

  The slave station terminal according to the present invention includes synchronization means, a switching circuit, disconnection detection means, and management monitoring data transmission means. The synchronization means is connected to a common data signal line to which a master station is connected, and takes transmission synchronization with the master station. The switching circuit has a load resistance with respect to an input signal line of an input unit corresponding to the local station and a switching function connected to the load resistance, and turns the switching function ON or OFF. The disconnection detecting means obtains output logic data from the input unit in a state where there is a detection target and a state where there is no detection target in a time zone in which the load resistance is turned on, and a time zone in which the load resistance is turned off. In addition, the detection target object logic data corresponding to the change in the internal current consumption due to the operation of the input unit is obtained, and the connection state of the input unit is normal based on the output logic data and the detection target object logic data. Determine whether it is abnormal or not. The management monitoring data transmission unit superimposes a signal constituting data indicating an abnormal connection state or a normal connection state of the input unit on the transmission signal.

  The load resistance may be turned ON only when data of its own station is transmitted. In this case, the switching circuit is configured such that the standby current of the input unit is in a time zone when the load resistance is turned OFF. It may have a high resistance with a flowing value.

  The disconnection detection means may switch and output the detected object logical data and other monitoring data to the management monitoring data transmission means.

  In the disconnection detection method according to the present invention, output logic data obtained with the load resistance turned on (hereinafter referred to as the input signal line being in an effective state) in a state where there is a detection target in the input section and a state where there is no detection target. As another unique data different from the above, the detection target object logic data corresponding to the change in the internal current consumption due to the operation of the input unit, which is obtained in the state where the load resistance is turned off (hereinafter, the input signal line is invalid) Have gained. Therefore, even if there is an abnormality such as a short circuit, open circuit or disconnection due to incorrect wiring of the input signal line, the output logic data is compared with the detected object logic data when not affected by the state of the input signal line. It is possible to determine whether or not such abnormality has occurred in the signal line.

  In determining, since each of the output logic data and the detection target object logic data is unique, a threshold value is set for each of the detection target presence state and the detection target absence state. As for each of the above data, whether or not there is a change from a state with a detection target to a state without a detection target or a change from a state without a detection target to a state with a detection target Also good. If the state of the input signal line is normal, the detection target object logic data and the output logic data should change in the same way. Conversely, there is a change in the detection target object logic data and a change in the output logic data. When there is no change, or when there is no change in the detected object logical data and there is a change in the output logical data, it can be determined that the connection state is abnormal. Also, by paying attention to the change of data, either the positive logic (OFF when there is no detection object, OFF) or the reverse logic (ON when there is detection object, OFF) type of sensor It can also be applied to.

  The state where the detection object is present and the state where there is no detection object in the input unit are intermittent, but it is not necessary to continuously obtain the output logic data and the detection object logic data corresponding to these states. It may be temporary data obtained at the synchronization timing. At this time, when comparing changes in the output logic data and the detection target object logic data, they are stored as temporary data.

  As described above, in the three-wire type sensor, it is possible to detect the presence or absence of a short circuit or disconnection of the power supply line relatively easily by using the standby current. Therefore, even in the disconnection detection method of the present invention, the short circuit or disconnection of the power supply line can be detected. The presence or absence can be detected together. Therefore, it is possible to detect a short circuit or disconnection of the power supply line in addition to the disconnection of the input signal line on the master station side by superimposing a signal constituting data indicating the type of abnormal connection state in the management data area. It becomes possible. Furthermore, if the signal constituting the detection object logical data is superimposed, the master station side can grasp the actual value of the detection object logical data and use it for more accurate detection of the abnormal state. it can. Furthermore, if the signal constituting the detection target object logic data and the signal constituting the other monitoring data are switched and superimposed, the other state relating to the failure is grasped and the abnormal state is detected more accurately. It becomes possible.

  Further, if data superposed on the management monitoring data area from the slave station is data other than “0”, the data extracted from the management monitoring data area at the master station is output from the slave station when the data extracted from the management monitoring data area is “0”. It can be said that information is not transmitted to the master station via the common data signal line. Therefore, at that time, it can be determined that the common data signal line is disconnected, and the disconnection of the common data signal line can be detected together with the abnormality of the input signal line.

  The slave station terminal according to the present invention includes a switching circuit that switches between an effective state and an invalid state of an input signal line of an input unit, a state with a detection target and a detection state in each state in which the input signal line is in a valid or invalid state. Based on the output logic data and the detected object logic data, the output logic data from the input section in the absence of the object and the detected object logic data corresponding to the change in the current consumption due to the operation of the input section are obtained. Since the disconnection detecting means for determining whether the connection state of the input unit is normal or abnormal is provided, it is suitable for the disconnection detection method according to the present invention.

  Furthermore, if the load resistance is turned on only when data is transmitted from the local station, the current consumption of the entire system can be kept low by using only one sensor that is turned on in the entire system. Can do. Further, if the switching circuit has a high resistance that allows the standby current of the input section to flow during the time period when the load resistance is turned OFF, even if the input section is a two-wire sensor, the three-wire The current consumption of the entire system can be suppressed in the same way as with the sensor.

It is a schematic diagram of a transmission system between a master station and a slave station in an embodiment of a control / monitor signal transmission system employing a disconnection detection system according to the present invention. 1 is a system configuration diagram showing a schematic configuration of a control / monitor signal transmission system. It is a system configuration | structure figure of a master station. It is a system block diagram of a slave station. It is a system block diagram of a disconnection detection means. It is a system block diagram of the 1st disconnection detection means to which the two-wire type sensor was connected. It is a graph which shows the difference in an electric current value. It is a time chart figure which shows the correlation of a signal. It is a time chart figure of a transmission clock signal. It is a schematic diagram of an IDX address data table stored in the master station.

An embodiment of a control / monitor signal transmission system employing the disconnection detection method according to the present invention will be described with reference to FIGS.
As shown in FIG. 2, the control / monitor signal transmission system includes a single master station 2 connected to the control unit 1 and the common data signal lines DP and DN (hereinafter also referred to as transmission lines), It comprises a plurality of input / output slave stations 4, output slave stations 6 and input slave stations 7 connected to the common data signal lines DP and DN. In FIG. 2, 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 input / output slave station 4, the output slave station 6, and the input slave station 7 are provided with a signal output process for the output unit 8 that operates in response to an output instruction from the control unit 1 and an input unit 9 that incorporates input information to the control unit 1. One or both of the input signal processing is performed. 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, or a photoelectric switch. And various sensors. 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).

  The control unit 1 is, for example, a programmable controller, a computer, and the like, and is extracted from the output unit 11 that sends out the control parallel data 13 and the control management parallel data 14, and the monitoring signals from the input / output slave station 4 and the input slave station 7. And an input unit 12 for receiving the first management monitoring parallel data 16 and the second management monitoring parallel data 17 obtained based on the management monitoring data extracted from the monitoring monitoring data 15 and the management monitoring data extracted from the management monitoring signal. . These output unit 11 and input unit 12 are connected to the master station 2. In addition, management judging means 18 for calculating data transmitted from the output unit 11 based on data received from the input unit 12 is provided.

  As shown in FIG. 3, 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. A control signal (hereinafter referred to as a transmission clock signal) that is connected to the common data signal lines DP and DN and is a series of pulse signals corresponding to the transmission signal of the present invention is connected to the common data signal lines DP and DN. Monitoring signal and management monitoring signal transmitted from the input / output slave station 4, the output slave station 6, or the input slave station 7 (hereinafter referred to as "slave stations 4, 6, 7" when referring to all of them) The monitoring parallel data 15, the first management monitoring parallel data 16 and the second management monitoring parallel data 17 extracted from the above are sent to the input unit 12 of the control unit 1.

  The output data unit 21 delivers the control parallel data 13 from the output unit 11 of the control unit 1 to the master station output unit 24 as serial data.

  The management data unit 22 includes a storage unit 29 that stores an IDX address table in which information on each of the slave stations 4, 6, and 7 is aggregated, and the control management parallel data 14 and the IDX address table from the output unit 11 of the control unit 1. Based on the above, management control data composed of first management control data ISTo and second management control data IDXo, which will be described later, is created and delivered to the master station output unit 24 as serial data. The IDX address table includes data for specifying any one of the input / output slave station 4, the output slave station 6 and the input slave station 7. In this embodiment, the IDX address table includes the data of the slave stations 4, 6, and 7. The start address is used. FIG. 10 shows an example of an IDX address table using the head address.

  As shown in FIG. 10, the station to which the address of # ad0 is assigned has a 1-bit monitoring signal data value, and the data in the IDX address table is a continuous value of # ad0 and # ad1. On the other hand, since the data value of the monitoring signal is 2 bits for the station to which the address of # ad1 is assigned, the pulse of # ad2 is also assigned to the same station as # ad1. Therefore, in the data of the IDX address table, # ad3 is stored as the next value of # ad1. In this embodiment, even if the data value of the monitoring signal is 1 bit, that is, # ad0 is also set as the head address similarly to # ad1. Further, the IDX address table of this embodiment also stores the classification data of the slave stations corresponding to each address. In the example shown in FIG. 10, “1” is assigned to the input slave station 7, “2” is assigned to the output slave station 6, and “3” is assigned to the input / output slave station 4. It is remembered.

  The timing generation unit 23 includes an oscillation circuit (OSC) 31 and a timing generation unit 32. Based on the OSC 31, the timing generation unit 32 generates a timing clock of this system and delivers it to the master station output unit 24.

  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 unit 21 and the management data unit 22 and the timing clock received from the timing generation unit 23, the control data generation unit 33 applies a series of data to the common data signal lines DP and DN via the line driver 34. A transmission clock signal is transmitted as a pulse signal.

  As shown in FIG. 1, the transmission clock signal has a control / monitoring data area following the start signal ST and a management data area following the control / monitoring data area. The control / monitoring data area includes control signal data OUTn (n is an integer) sent from the master station 2 and monitoring signal data INn (n is an integer) sent from the input / output slave station 4 or the input slave station 7. Consists of. As shown in FIG. 9, the pulse of the transmission clock signal has a high potential level (+ 24V in this embodiment) in the second half of one cycle and a low potential level (+ 12V in this embodiment) in the first half. The pulse width interval of the first half of the pulse that becomes the level becomes the output data period, and the first half of the pulse that becomes the low potential level also becomes the input data period. The pulse width interval of the low potential level represents the control signal data OUTn, and the presence or absence of the current superimposed on the low potential level represents the monitoring signal data INn. In this embodiment, when one cycle of the transmission clock signal is t0, the pulse width interval of the low potential level is extended from (1/4) t0 to (3/4) t0. As long as it corresponds to the value of each data of the control parallel data 13, the width is not limited and may be determined appropriately. Also, the input data period and the output data period can be appropriately determined. For example, the input data period is set to the first half of the pulse (low potential level) as in this embodiment, and the pulse width interval of the second half of the pulse (high potential level) is set. Alternatively, the output data period may be the first half of the pulse (low potential level) and the second half of the pulse (high potential level) may be the input data period as in this embodiment. Further, the latter half of the pulse (high potential level) may serve as both the output data period and the input data period. The same applies to the case where the second half of one cycle of the transmission clock signal is at a low potential level. In FIG. 1, the upper row shows the output data period, and the lower row shows the input data period.

  The management data area of the transmission clock signal includes a management control data area in which the management control signal transmitted from the master station 2 is superimposed, and management monitoring data in which the management monitoring signal transmitted from the slave stations 4, 6, 7 is superimposed. Consists of regions. The management control data transmitted by the management control signal is composed of the first management control data ISTo and the second management control data IDXo, and is expressed as a pulse width interval of a low potential level, like the control signal data OUTn. Further, the management monitoring data transmitted by the management monitoring signal is composed of the first management monitoring data STi and the second management monitoring data IDXi. Like the monitoring signal data INn, the presence / absence of the current superimposed on the low potential level is determined. expressed. In this embodiment, the first management control data ISTo and the second management control data IDXo are instruction data for specifying the type of data requested to the slave stations 4, 6, 7, or the slave stations 4, 6, 7 Address data for specifying any one of these. On the other hand, the first management monitoring data STi and the second management monitoring data IDXi are data indicating the status of the own station, and data other than “0” is always transmitted as management monitoring data. Details will be described later.

  The start signal ST has the same potential level as the high potential level of the transmission clock signal and is a signal longer than one cycle of the transmission clock signal.

  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 and the management monitoring signal sent from the slave stations 4, 6, and 7 via the common data signal lines DP and DN. As described above, the data values of the monitoring signal and the management monitoring signal are represented by the presence / absence of a current superimposed on the low potential level. After the start signal ST is transmitted, first, the input / output slave station 4 or the input A monitoring signal is sequentially received from each of the slave stations 7, and subsequently, a management monitoring signal is received from any one of the slave stations 4, 6, and 7. Data of the monitoring signal and the management monitoring signal is extracted by the monitoring data extracting unit 36 in synchronization with the signal of the timing generating unit 32. The monitoring signal data is sent to the input data unit 26 as serial input data 37. Management monitoring data 39 extracted from the management monitoring signal is also sent to the input data unit 26.

  The input data unit 26 converts the serial input data 37 received from the master station input unit 25 into parallel (parallel) data, and sends the parallel data to the input unit 12 of the control unit 1. Further, the management monitoring data 39 received from the master station input unit 25 is separated into the first management monitoring parallel data 16 and the second management monitoring parallel data 17 and sent to the input unit 12.

  The input slave station 7 corresponds to the slave station terminal of the present invention. As shown in FIG. 4, the transmission receiving means 41, the management control data extracting means 42, the address extracting means 43, the address setting means 44, the management monitoring data A slave station input unit 70 having a transmission unit 45, a monitoring data transmission unit 46, an input unit 47, and a second disconnection detection unit 48 is provided. Further, a first disconnection detecting means 49 disposed between the slave station input unit 70 and the input unit 9 is provided. 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.

  Similarly to the input slave station 7, the output slave station 6 includes an MCU that is a microcomputer control unit as an internal circuit, and this MCU functions as a 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.

  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 the slave station input / output unit 40. It has become a thing. 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.

  The transmission receiving means 41 of the input slave station 7 receives the transmission clock signal transmitted to the common data signal lines DP and DN, and receives them as management control data extracting means 42, address extracting means 43, and management monitoring data transmitting means 45. To hand over. The management control data extraction unit 42 extracts the management control signal data from the management data area of the transmission clock signal, and delivers them to the second disconnection detection unit 48. On the other hand, the address extracting means 43 counts pulses starting from the start signal ST indicating the start of the transmission clock signal, and transmits the monitoring data at a timing when the count value coincides with its own address data set by the address setting means 44. A control signal is delivered to the means 46 and the first disconnection detecting means 49. Note that transmission clock data (CK) obtained from transmission clock signals transmitted to the common data signal lines DP and DN is also input to the first disconnection detection means 49.

  The monitoring data transmitting unit 46 sets the base current of the transistor TR to “on” or “off” based on the serial data delivered from the input unit 71 at the timing when the control signal is delivered from the address extracting unit 43. When the base current is “on”, the transistor TR is turned “on”, and a current signal as a monitoring signal is output to the common data signal lines DP and DN. In this embodiment, as shown in FIG. 9, when the data value of the monitoring data is “1”, it is expressed by flowing a current (for example, 30 mA) of a predetermined value Ith or more. Therefore, for example, the monitoring data at addresses 0 (# ad0), 1 (# ad1), 2 (# ad2), and 3 (# ad3) of the signal shown in FIG. It represents 0 ”,“ 1 ”,“ 0 ”. The data delivered from the input unit 47 to the monitoring data transmission unit 47 is based on the output logic data from the input unit 9.

  The management monitoring data transmission means 45 counts pulses starting from the start signal ST of the transmission clock signal, and obtains the timing of the management data area. Then, based on the data delivered from the second disconnection detecting means 48, the base current of the transistor TR is output, and a current signal which is a management monitoring signal is output to the common data signal lines DP and DN.

  As shown in FIG. 5, the first disconnection detection means 49 includes a gate circuit 58, a switching circuit 59, and an A / D converter 60.

  The gate circuit 58 receives a control signal from the address extraction unit 43 and receives transmission clock data CK obtained from a transmission clock signal transmitted to the common data signal lines DP and DN. Then, the transistor TRs of the switching circuit 59 is turned on in the first half of the pulse (low potential level period) at the timing at which the local station address matches in the transmission clock signal, the load resistance Rs and the high resistance Rh are enabled, and the input signal of the input unit 9 The line Ls becomes valid. At this time, if the input unit 9 is in a state where there is an object to be detected, the output logic data is output via the input signal line Ls, the logic data is inverted, and the input means 47 and the second disconnection determination means 48 Delivered. At the time of the high level rising in the second half of the pulse (high potential level period), the transistor TRs of the switching circuit 59 is turned off, the high resistance Rh is enabled, the input signal line Ls of the input unit 9 is disabled, and almost current flows. Disappear. At this time, even when the input unit 9 is in the state with the detection target, the current hardly flows, and the output logic data is the same as in the state without the detection target. On the other hand, the current signal in the ground side connection Lg flows through the low resistance Rg, and the voltage signal generated there is converted into digital data by the A / D converter 60. Regardless of the state of the input unit 9, the signal is output to the second disconnection detecting means 48 via the A / D converter 60.

  Note that when the transistor TRs is in an OFF state, even if the input unit 9 is in a state where there is an object to be detected, almost no current flows through the input signal line Ls. Never do. For example, if the input unit 9 is a general three-wire sensor, the sensor load current when the transistor TRs is ON may be about 20 mA when the sensor is ON (the detection target is present). If there are 50, a current consumption of about 1 A flows, and the transmission signal of the common data signal line (transmission line) drops. However, in the present invention, only when the data of the slave station terminal is transmitted by the transmission synchronization method, the sensor which is turned on by the transistor TRs is switched on and off by the transistor TRs. Thus, the current consumption of the entire system is suppressed to about 20 mA or less.

  Further, when the input unit 9 is a two-wire sensor as shown in FIG. 6, the two-wire sensor is connected between the input signal line Ls and the ground side connection Lg, and is switched in the first half of the pulse (low potential level period). 59 transistor TRs is turned on, the load resistance Rs is activated, and the input signal line Ls of the input unit 9 is activated. At the time of the high level rising in the second half of the pulse (high potential level period), the transistor TRs of the switching circuit 59 is turned off, the high resistance Rh is enabled, the input signal line Ls of the input unit 9 is disabled, and almost no current flows. . At this time, if the high resistance Rh is set to a value through which the standby current of the two-wire sensor flows, the current consumption of the entire system can be suppressed as in the case of the three-wire sensor.

  The transistor TRs of the switching circuit only needs to be able to switch between the load resistance Rs and the high resistance Rh, and other known contactless switches may be used.

  As shown in FIG. 5, the second disconnection detection means 48 includes an ISTo extraction means 51, an IDXo extraction means 52, a slave station address designation detection means 53, a threshold storage means 54, an operation comparison means 55, a disconnection determination means 56, an encoding. Means 57 and data adding means 61 are included.

  The ISTo extraction means 51 extracts the first management control data ISTo from the management control signal data delivered from the management control data extraction means 42 and delivers it to the slave station address designation detection means 53. Further, the IDXo extraction unit 52 extracts the second management control data IDXo from the management control signal data delivered from the management control data extraction unit 42, and delivers it to the slave station address designation detection unit 53. The local station address data is delivered from the address setting unit 44 to the slave station address designation detection unit 53.

  The slave station address designation detection unit 53 compares the second management control data IDXo with the data value of the local station address, and when they match, the predetermined address data is encoded by the encoding unit 57 or the gate according to the first management control data ISTo. Delivered to means 61. That is, when the first management control data ISTo is data for instructing monitoring of the disconnection state of the input unit 9, the error monitor command data is delivered to the encoding means 57 and the data adding means 61.

  The operation comparison means 55 performs ON / OFF determination of the detection target object logic data and connection determination of the power supply side connection Lv and the ground side connection Lg. If there is an object to be detected when the input signal line Ls is valid, there is an object to be detected due to the influence of a large load current (about 27 mA) with respect to the current ion of the ground side signal line as shown in FIG. The detected object logical data in the state of cannot be detected. Therefore, in a state where the input signal line Ls is invalidated, the operation comparison unit 55 stores the data (data corresponding to the current value) delivered from the A / D converter 60 of the first disconnection detection unit 49 as a threshold storage unit. Compared with the threshold values K0a, Kab, Kbc delivered from 54, the connection determination of the power supply side connection Lv and the ground side connection Lg is performed. Note that the data delivered from the A / D converter 60 is detected object logic data in the input unit 9 in a state where the input signal line Ls is invalid and in the state where the detection target is present and in the state where there is no detection target. There are three types, i0u, i0d, and overcurrent ie due to circuit failure of the input unit 9.

  As shown in FIG. 7, when the input unit 9 has no detection target, the minimum operating current value of the input unit 9 (this embodiment) is connected to the ground side connection Ls regardless of the valid / invalid state of the input signal line Ls. Then, about 2 mA) will flow. Therefore, if the minimum current threshold value K0a or less considering the fluctuation width of the minimum operating current value is considered, this is a disconnection abnormality of the power supply side connection Lv or the ground side connection Lg. On the other hand, if the power supply side connection Lv and the ground side connection Lg are normal, the internal consumption caused by the operation display LED of the input unit 9 that is turned on or off in accordance with the presence or absence of the detection object. A change in current occurs. Therefore, the detection target object logical data is compared with the threshold value Kab for distinguishing the detection target object presence / absence state of the detection target object logical data from the detection target object logical data. If it is larger than the threshold value Kab, it is determined that the detected object logical data is ON. Furthermore, if there is an abnormality in the internal circuit of the input unit 9, an overcurrent ie that is larger than the current i0u in the state where the detection target is present flows, so that the overcurrent threshold Kbc that takes into account the fluctuation width of the current value of the current i0u is exceeded. If there is, it is determined that the internal circuit of the input unit 9 is abnormal.

  The operation comparison unit 55 delivers the data D2 indicating ON / OFF of the detected object logical data determined by the comparison method to the disconnection determination unit 56. Further, when it is determined that the disconnection is abnormal, data D1 indicating disconnection is output, and when it is determined that the internal circuit is abnormal, data D3 indicating internal circuit abnormality is output to the disconnection determination means 56. The threshold values K0a, Kab, and Kbc stored in the threshold value storage unit 54 are downloaded from the control unit 1 side, and the download procedure will be described later.

  The disconnection determination means 56 is provided with presence / absence of data change of the data D2 indicating ON / OFF of the detection target object logic data delivered from the operation comparison means 55, and output logic data change delivered from the first disconnection detection means 49. If there is a change or no change, the input signal line Ls is normal, and if there is a change on one side and no change on the other, the input signal line Ls is determined to be abnormal. Then, the input signal line abnormality data Db is delivered to the encoding means 57. When the data D1 indicating the disconnection abnormality or the data D3 indicating the internal circuit abnormality is delivered from the operation comparison unit 55, the disconnection abnormality data Da or the internal circuit abnormality data Dc corresponding to the data D1 is delivered to the encoding unit 57. Further, when there is no abnormal data Da, Db, Dc, normal data Dd is generated and delivered to the encoding means 57. The delivery of the output data Da, Db, Dc, Dd to the encoding means 57 is executed at a timing when the output data of the address extraction means 43 is turned from ON to OFF.

  A method for determining whether the input signal line Ls is abnormal or normal in the disconnection determination means 56 will be described with reference to FIG. The disconnection determination means 56 stores the output logic data ON / OFF delivered from the first disconnection detection means 49 and the detection target object logic data ON / OFF delivered from the operation comparison means 55, respectively, and the previous transmission. Compared with the old data stored in the cycle (a series of signals up to the next start signal, which is composed of the start signal ST, the control / monitoring data area and the management data area) For each of the logical data and the detection target object logical data, a change from the state with the detection target in the input unit 9 to the state without the detection target, or from the state without the detection target to the state with the detection target Determine if there has been a change. As shown in FIG. 8, even when the input signal line Ls is disconnected, ON / OFF of the detection target object logic data is determined by the current value ig at the falling timing of the second half of the pulse of the transmission clock signal. On the other hand, the output logic data is detected when the input signal line Ls is disconnected even though the detected object logic data changes from the state without the detection object to the state with the detection object. There is no change in the state of nothing. Accordingly, since there is a change on one side and no change on the other, it can be determined that the input signal line Ls is disconnected.

  Based on the first management control data ISTo delivered from the slave station address designation detection means 53, the encoding means 57 outputs the abnormal data Da, Db, Dc and normal data Dd output from the disconnection determination means 56 to a predetermined code. The data is converted into data and transferred to the management monitoring data transmission means 45. Specifically, first, when the first management control data ISTo is data for instructing monitoring of the disconnection state of the input unit 9, as the first management monitoring data STi, the power supply side connection Lv or the ground side connection Lg Code data indicating the disconnection state, the disconnection state of the input signal line Ls, the internal circuit abnormal state or the normal state is delivered to the management monitoring data transmission means 45.

  When the error monitor command data is delivered from the slave station address designation detecting means 53, the data adding means 61 converts the detected object logical data delivered from the A / D converter 60 to the first management monitoring data STi. Then, it is handed over to the management monitoring data transmitting means 45 as the second management monitoring data IDXi.

  At this time, a value other than “0” is adopted for the first management monitoring data STi delivered to the management monitoring data transmitting means 45, that is, the code data indicating each abnormal data Da, Db, Dc and normal data Dd. . Therefore, data other than “0” is transmitted as management monitoring data. That is, when the management monitoring data is “0”, it can be said that the information output from the input slave station 7 is not transmitted to the master station via the common data signal lines DP and DN. Therefore, at that time, it can be determined that the common data signal lines DP and DN are disconnected.

Next, the procedure of the disconnection detection method in the control / monitoring signal transmission system having the above configuration will be described.
The control unit 1 outputs management control parallel data 14 for instructing detection of an input signal line disconnection of the input unit 9 to the master station 2 at an appropriately set timing or by an arbitrary input instruction by a user. Receiving this, the master station 2 receives the first management control data ISTo requesting the presence / absence information on the detection of the disconnection of the input signal line, and the second management designating one of the data groups stored in the IDX address table. Control data IDXo is output. Note that the IDX address data table shown in FIG. 10 has already been created in the management data section 22 of the master station 2, and a transmission comprising a start signal ST, a control / monitoring data area, and a management data area following the start signal ST For each cycle, the start address assigned to all of the input slave stations 7 is sequentially specified by the second management control data IDXo.

  The designation of data in the IDX address table by the second management control data IDXo is in accordance with the table number. That is, first, the index address data (# ad0) of the table number 1 is selected and output as the second management control data IDXo. Then, every transmission cycle, the slave station classification data is sequentially changed to head address data corresponding to each table number having “1”. However, the order in which the data of the IDX address table is designated by the second management control data IDXo is not limited, and may be in accordance with the priority order by function, for example.

  When the second management control data IDXo matches the own station address, the input slave station 7 outputs the disconnection abnormality data Da of the power source side connection Lv or the ground side connection Lg and the input signal line abnormality data output from the disconnection determination means 56. Based on Db, internal circuit abnormality data Dc or normal data Dd, a management monitoring signal composed of data indicating abnormality or normality is superimposed on the management monitoring data area. In response to this, the master station 2 extracts management monitoring data from the management monitoring signal and delivers it to the control unit 1.

  In the control unit 1, predetermined processing is executed according to the contents of the first management monitoring parallel data 16. Specifically, if the first management monitoring parallel data 16 indicates an abnormality, an abnormality display is performed. If the management monitoring data is “0”, it is determined that the common data signal lines DP and DN are disconnected, and a message to that effect is displayed.

  Through the above procedure, the control unit 1 can grasp the presence or absence of connection abnormality or internal circuit abnormality for each of the input units 9 corresponding to the input slave station 7.

  Note that the threshold values K0a, Kab, and Kbc can be changed as appropriate from the control unit side. In that case, the data indicating that the threshold values K0a, Kab and Kbc are to be changed and the data of the changed threshold values K0a, Kab and Kbc are superimposed on the management control data area, and these are extracted on the input slave station 7 side. Just do it.

  The output logic data of this embodiment is positive logic that is ON when there is a detection target and OFF when there is no detection target. Since the change state of the detection target object logic data in the input unit is compared to determine the connection state of the input signal line, even if the output logic data and the detection target object logic data are reverse logic, It is possible to determine whether there is an input signal line connection abnormality or internal circuit abnormality.

  In this control / monitor signal transmission system, it is possible to monitor data different from the detected object logical data. In this case, the gate means 62 indicated by an imaginary line in FIG. 5 is provided, and the data 63 to be monitored is input to the gate means 62 and command data corresponding to the data is sent from the slave station address designation detecting means 53. Output. Then, by transmitting the input monitor command data as the first management control data ISTo from the master station 2 to the corresponding input / output slave station 4, output slave station 6, and input slave station 7, the A / Since the output data of the D converter 61 and the monitoring data 63 are switched and output as management monitoring data, this can be grasped on the control unit 1 side.

1 Control Unit 2 Master Station 4 Input / Output Slave Station 5 Controlled Device 6 Output Slave Station 7 Input Slave Station 8 Output Unit 9 Input Unit 11 Output Unit 12 Input Unit 13 Control Parallel Data 14 Management Control Parallel Data 15 Monitoring Parallel Data 16 One management monitoring parallel data 17 Second management monitoring parallel data 18 Management judging means 21 Output data section 22 Management data section 23 Timing generating section 24 Master station output section 25 Master station input section 26 Input data section 29 Storage means 31 OSC (oscillation circuit )
32 Timing generation means 33 Control data generation means 34 Line driver 35 Monitoring signal detection means 36 Monitoring data extraction means 37 Input data 39 Management monitoring data 40 Slave station input / output unit 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 Monitoring data transmission means 47 Input means 48 Second disconnection detection means 49 First disconnection detection means 51 ISTo extraction means 52 IDXo extraction means 53 Slave station address designation detection means 54 Threshold storage means 55 Operation Comparison means 56 Disconnection judgment means 57 Encoding means 58 Gate circuit 59 Switching circuit 60 A / D converter 61 Data addition means 62 Gate means 63 Monitoring data 70 Slave station input unit 80 Output unit integrated slave station 90 Input unit integrated unit Station D1 Data D2 indicating disconnection abnormality Output object logic data D3 data indicating ON / OFF data D3 data indicating internal circuit error Da disconnection error data Db input signal line error data Dc internal circuit error data Dd input signal line error data Lv power supply side connection Ls input signal line Lg Ground Side connection TR, TRs Transistor Rg Low resistance Rh High resistance Rs Load resistance

Claims (9)

In a control / monitor signal transmission system in which a master station and a plurality of slave stations are connected by a common data signal line and data is transmitted by a transmission synchronization method.
The transmission signal transmitted to the common data signal line is provided with a management data area different from the control / monitor data area composed of control signal data and monitoring signal data,
The slave station corresponding to the input unit is provided with a time band for turning on or off the load resistance of the input unit in a state where the input signal line of the input unit is normally connected, and the time when the load resistance is turned on The output logic data from the input unit in the state with the detection target and without the detection target obtained in the band, and the internal current consumption due to the operation of the input unit obtained in the time zone when the load resistance is turned off On the basis of the detection target object logic data corresponding to the change of the input object, it is determined whether the connection state of the input unit is normal or abnormal, the connection data abnormal state or the connection normal state of the input unit in the management data area The disconnection detection system characterized by superimposing the signal which comprises the data to show.   For each of the output logic data and the detection target object logic data, a threshold value is set for distinguishing between the state with the detection target and the state without the detection target, and the detection from the state with the detection target For each of the output logic data and the detection object logic data, the presence / absence of a change to a state without an object or the presence / absence of a change from a state without the detection object to a state with the detection object is obtained. When the detection object logical data changes and the output logical data does not change, or when the detection object logical data does not change and the output logical data changes, the connection state is abnormal. The disconnection detection system according to claim 1 for determination.   The output logic data and the detected object logical data are temporary data obtained at a predetermined timing, and the slave station includes storage means for storing the output logical data and the detected object logical data. The disconnection detection method according to 1 or 2.   The management data area includes a management control data area in which data from the master station is superimposed and a management monitoring data area in which data from the slave station is superimposed, and the management monitoring data area from the slave station The data superimposed on the data is determined as data other than “0”, and when the data extracted from the management monitoring data area in the master station is “0”, it is determined that the common data signal line is disconnected. Or the disconnection detection system of 3.   5. The disconnection detection according to claim 1, wherein the slave station switches and superimposes a signal constituting the detected object logical data and a signal constituting other monitoring data in the management data area. method. A synchronization means connected to the common data signal line to which the master station is connected, and for synchronizing transmission with the master station;
A load resistor for the input signal line of the input unit to which the own station corresponds, a switching circuit connected to the load resistor, and a switching circuit for turning the switching function ON or OFF;
In the time zone when the load resistance is turned on, the output logic data from the input unit in the state with the detection target and without the detection target is obtained, and in the time zone when the load resistance is turned off, Whether the detection target object logic data corresponding to the change in the internal current consumption due to the operation is obtained, and whether the connection state of the input unit is normal or abnormal based on the output logic data and the detection target object logic data Disconnection detecting means for determining
A slave station terminal comprising management monitoring data transmitting means for superimposing a signal constituting data indicating an abnormal connection state or a normal connection state of the input unit on the transmission signal.   7. The slave station terminal according to claim 6, wherein the load resistance is turned on only when data of the local station is transmitted.   8. The slave station terminal according to claim 7, wherein the switching circuit has a high resistance that is set to a value through which a standby current of the input unit flows during a time period when the load resistance is turned off.   9. The slave station terminal according to claim 6, 7 or 8, wherein the disconnection detection means switches and outputs the detected object logical data and other monitoring data to the management monitoring data transmission means.

Images