Abstract:
A data collection system includes a plurality of sensor modules each provided with a sensor unit, and a data collecting device. The data collecting device ( 200 ) is provided with: a clock output unit ( 201 ) which outputs a clock signal; an enable signal output unit ( 202 ) which outputs to a prescribed sensor module ( 100 ) an enable signal at intervals equal to or greater than the number of clock signals corresponding to the number of sensor modules ( 100 ); a counter ( 203 ) which counts the number of clock signals; and a sensor signal input unit ( 205 ) into which data output by the sensor modules ( 100 ) is input via a bus line, and which records said data in association with the count value. Using the clock signal as a trigger, each sensor module ( 100 ) functions as a shift register feeding the enable signal to the subsequent stage sensor module ( 100 ), and each sensor module ( 100 ) outputs output data from the sensor unit ( 110 ) in said sensor module ( 100 ) to the sensor signal input unit ( 205 ) only when the enable signal has been fed to said sensor module ( 100 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a data collection system configured to collect data from a plurality of sensors, and more particularly, to a data collection system capable of reducing complexity of wirings even when there are many sensors. 
       RELATED ART 
       [0002]    A plurality of sensors is arranged at a target such as a facility, a structure and the like, and data is collected from the respective sensors so as to monitor or inspect a state of the target. For example, in order to detect a local reduction in thickness or a defect of a piping caused due to corrosion, erosion or the like, a data collection system having hundreds of magnetic sensors arranged at the piping and configured to collect data, which is to be output from the respective magnetic sensors, has been put to practical use. A data collection system having sensors such as thermometers, hygrometers and the like arranged at respective parts in a plant or the like and configured to collect data, which is to be output from the respective sensors, has also been put to practical use. 
         [0003]      FIG. 6  is a block diagram depicting a configuration example of a data collection system  500  of the related art. As shown in  FIG. 6 , the data collection system  500  includes a plurality of sensors  510 , a data collection apparatus  520  and a wiring switch  530 . 
         [0004]    The data collection apparatus  520  is configured to feed power to the sensors  510  of connection destinations and to receive data measured by the sensors  510 . The respective sensors  510  and the data collection apparatus  520  are interconnected via the wiring switch  530 . The data collection apparatus  520  is configured to control the wiring switch  530  by a switching signal and to sequentially switch the sensors  510  of connection destinations for data collection. 
         [0005]    In general, the many sensors  510  are connected to the data collection apparatus  520 . However, it is preferably to sequentially acquire the data, in many cases. For this reason, the wiring switch  530  is used in view of the connection aspect. 
       CITATION LIST 
     Patent Documents 
       [0006]    Patent Document 1: Japanese Patent Application Publication No. 2008-175638A 
       SUMMARY OF THE INVENTION 
     Problems to be Solved 
       [0007]    In the data collection apparatus  520  of the related art, it is necessary to individually interconnect the wiring switch  530  and the respective sensors  510 . Also, a plurality of wirings such as a wiring for data signal and a wiring for power feed is adopted for each of the sensors. When the number of the sensors  510  is large, the number of the wirings is massive. For this reason, the wiring of the sensors  510  is troublesome. 
         [0008]    It is therefore an object of the present invention to provide a data collection system capable of reducing complexity of wirings even when there are many sensors. 
       Means for Solving Problems 
       [0009]    In order to achieve the above object, according to the present invention, there is provided a data collection system including a plurality of sensor modules each having a sensor unit, and a data collection apparatus. The data collection apparatus includes a clock output unit configured to output a clock to each sensor module, an enable signal output unit configured to output an enable signal to a predetermined sensor module at an interval equal to or greater a number of clocks corresponding to the number of the sensor modules, a counter configured to count the number of clocks, and a sensor signal input unit configured to receive data, which is output from the sensor modules, via a bus line and to record the data in association with a count value. Each of the sensor modules is configured to function as a shift register configured to send the enable signal to a subsequent stage sensor module by using the clock as a trigger, and to output data of the sensor unit to the sensor signal input unit via the bus line only when the enable signal has been sent. 
         [0010]    Herein, each of the sensor modules may include an amplifier configured to switch between enable and disable states by the enable signal. 
         [0011]    Also, the data collection apparatus may be configured to feed power by a power supply line bus-connected to each sensor module. 
         [0012]    In this case, the sensor module may include a switch configured to switch the power feeding to the sensor unit by the enable signal. 
         [0013]    Also, the data collection apparatus may be configured to record a count value corresponding to the sensor module for which it is not necessary to input data, and to shorten an interval of the clocks upon counting of the count value. 
         [0014]    Also, the counter may be configured to reset the count value upon output of the enable signal. 
       Effects of the Invention 
       [0015]    According to the present invention, it is possible to provide the data collection system capable of reducing complexity of wirings even when there are many sensors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a block diagram depicting a configuration of a data collection system in accordance with an exemplary embodiment. 
           [0017]      FIG. 2  is a block diagram depicting specific configuration examples of a sensor module and a data collection apparatus. 
           [0018]      FIG. 3  is a flowchart depicting a data collection sequence in the data collection system of the exemplary embodiment. 
           [0019]      FIG. 4  is a block diagram depicting another configuration example of the data collection system of the exemplary embodiment. 
           [0020]      FIG. 5  depicts an example of a unitized sensor module. 
           [0021]      FIG. 6  is a block diagram depicting a configuration example of a data collection system of the related art. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0022]    An exemplary embodiment of the present invention will be described with reference to the drawings.  FIG. 1  is a block diagram depicting a configuration of a data collection system  10  in accordance with an exemplary embodiment. As shown in  FIG. 1 , the data collection system  10  includes a plurality of sensor modules  100  and a data collection apparatus  200 . 
         [0023]    The respective sensor modules  100  and the data collection apparatus  200  are connected by a data signal line and a power supply line in a bus-type topology form. For this reason, since it is not necessary to independently make a wiring for each sensor module  100 , it is possible to reduce the complexity of the wirings even though the number of the sensor modules  100  is large. 
         [0024]    Also, the data collection apparatus  200  and the sensor modules  100  are interconnected by a switching control line. The switching control line includes a clock signal line and an enable signal line. The clock signal line is connected by the bus-type topology, and the enable signal line is connected in a loop or cascade shape (refer to  FIG. 2 ). For this reason, the sensor modules  100  are connected to the enable signal line in a multi-stage manner. 
         [0025]    Each sensor module  100  has a sensor unit  110  and a signal switching unit  120 . The sensor unit  110  is configured to be supplied with power from the data collection apparatus, to measure physical amounts such as temperature, voltage, magnetism and the like, and to output the measured physical amounts as analog data of a predetermined range. A measurement target of each sensor module  100  is not required to be the same as long as the sensor unit  110  of each sensor module  100  has the same interface of the data output. 
         [0026]    The signal switching unit  120  is configured to be supplied with the power from the data collection apparatus  200  via the power supply line and to output data, which is to be output from the sensor unit  110 , to the data collection apparatus  200  via the data signal line. The signal switching unit  120  of each sensor module  100  is configured to perform a sequential operation by receiving a switching control signal from the data collection apparatus  200  via a switching control line. Thereby, the data collection apparatus  200  can sequentially receive the data from the respective sensor modules  100 . 
         [0027]      FIG. 2  is a block diagram depicting specific configuration examples of the sensor module  100  and the data collection apparatus  200 . As shown in  FIG. 2 , the signal switching unit  120  of the sensor module  100  includes an amplifier  121  having a disable function and a D-type flip-flop  122 . Also, the data collection apparatus  200  includes a clock output unit  201 , an enable signal output unit  202 , a counter  203 , an enable signal input unit  204 , a sensor signal input unit  205 , a sensor managing table  206 , and a power supply unit  210 . 
         [0028]    In the signal switching unit  120 , a Q output of the D-type flip-flop  122  is inverting input to a disable terminal of the amplifier  121  having a disable function and becomes a D input of the subsequent stage signal switching unit  120  by the enable signal line. At this time, as the D input of the first stage sensor module  100 , an output signal of the enable signal output unit  202  is input by the enable signal line, and the Q output of the final stage sensor module  100  is input to the enable signal input unit  204  by the enable signal line. 
         [0029]    A clock from the clock output unit  201  is input to a clock terminal CLK of each D-type flip-flop  122  by a clock signal line. For this reason, the D-type flip-flop  122  of the respective sensor modules  100  connected in the multi-stage manner forms a shift register configured to shift the enable signal, which is to be output from the enable signal output unit  202 , to a subsequent stage for each clock of the clock output unit  201 . In the meantime, when the shift register is formed by each sensor module  100 , a circuit except for the D-type flip-flop  122  may be used for the configuration. 
         [0030]    The amplifier  121  having a disable function is configured so that an output is a high impedance at a disable state, and is configured to amplify analog data, which is to be output by the sensor unit  110  at an enable state, and to output the same to the data signal line. That is, the output data of the sensor unit  110  is sent to the data collection apparatus  200  only when the enable signal is sent from the previous stage. The sensor module  100  at this time is referred to as ‘enable state’. 
         [0031]    However, instead of the amplifier  121  having a disable function, a normal amplifier and an output switch in which on and off states of the output switch is switched by the Q output of the D-type flip-flop  122  may be used. 
         [0032]    In the data collection apparatus  200 , the clock output unit  201  is configured to output a clock with a predetermined period. The clock output unit can also output a clock at a higher speed than normal or stop the same. 
         [0033]    The enable signal output unit  202  is configured to output an enable signal (H) at an interval equal to or greater a number of clocks corresponding to the number of the stages of the sensor modules  100 . For this reason, a situation where the plurality of sensor modules  100  becomes at the enable state at the same time does not occur. 
         [0034]    The counter  203  is configured to count the number of clocks. The counter  203  resets a count value when the enable signal output unit  202  outputs the enable signal (H). Thereby, it is possible to associate the count value of the counter  203  and the sensor module  100  at the enable state each other. 
         [0035]    The enable signal input unit  204  is configured to receive the enable signal that is to be output by the final stage sensor module  100 . Thereby, it is possible to check that the enable signal has been shifted to all the sensor modules  100 . Also, it is possible to check the number of the sensor modules  100  by referring to the count value of the counter  203  at the time when the enable signal input unit  204  receives the enable signal. However, the enable signal input unit  204  may be omitted. 
         [0036]    The sensor signal input unit  205  is configured to receive the data output from the sensor module  100  and to digital-convert the same. It is possible to specify from which the sensor module  100  the data is output by referring to the count value of the counter  203 . On the other hand, the digital conversion may be performed at the sensor module  100 -side. 
         [0037]    The sensor managing table  206  is configured to record the data, which is received by the sensor signal input unit  205 , in association with the count value. Attributes and the like of the sensor unit  110  may also be recorded. Also, when there is a defective sensor module  100  or the sensor module  100  that is not required to be measured, the count value corresponding to such a sensor module  100  may be recorded. In this case, when the counter  203  counts the count value, it is possible to reduce time devoted to the data collection by sending the clock at high speed. 
         [0038]    The data collection system  10  having the above configuration can perform the data collection in accordance with a sequence as shown in  FIG. 3 . That is, at a timing of the data collection, the data collection system initializes the D-type flip-flops  122  of the respective sensor modules  100  (S 101 ). In the meantime, the timing of the data collection may be continuous or a predetermined interval or may be based on a user&#39;s instruction, for example. 
         [0039]    The initialization of the D-type flip-flops  122  is made by outputting the clocks equal or greater the number of the sensor modules  100  with the output of the enable signal output unit  202  being kept at a low state (L). At this time, in order to shorten the processing time, the clocks are preferably sent at higher speed than normal. Alternatively, a reset signal line may be provide and the D-type flip-flops  122  may be initialized all together by the reset signal line. 
         [0040]    Then, the data collection system sets the output of the enable signal output unit  202  to a high state (H) and outputs the enable signal (S 102 ). Thereby, the counter  203  is reset. At the state where the output of the enable signal output unit  202  is the high state (H), when the clocks are output (S 103 ), the count value of the counter  203  proceeds, and the first stage sensor module  100  is at the enable state and the data of the sensor units  110  is output. Then, the data collection system records the data input to the sensor signal input unit  205  in the sensor managing table  206  in association with the count value (S 104 ). 
         [0041]    Thereafter, the data collection system sets the output of the enable signal output unit  202  to the low state (L) (S 105 ) and outputs the clocks (S 106 ). Thereby, since the count value of the counter  203  proceeds and the sensor modules  100  become at the enable state in a sequential order, the data collection system records the data input to the sensor signal input unit  205  in the sensor managing table  206  in association with the count value (S 107 ). In the meantime, as the period of the clock, a period suitable for the data collection system  10  can be arbitrarily set. 
         [0042]    The data collection system repeats the processing of outputting the clocks (S 106 ) and recording the input data (S 107 ) until the enable signal input unit  204  inputs the enable signal (S 108 ). On the other hand, the data collection system may repeat the processing until the count value of the counter  203  reaches the number of the sensor modules  100 . 
         [0043]    By the above sequence, it is possible to sequentially collect the data from all the sensor modules  100 . As described above, the data collection system may be configured to continuously perform next data collection processing immediately after the data collection processing shown in  FIG. 3  is over or to perform next data collection processing at a predetermined or unspecific interval. 
         [0044]    In general, the amplifier  121  having a disable function is at a power saving mode under the disable state. Therefore, the data collection system  10  of the exemplary embodiment can prevent an increase in power consumption even though the power is fed to the sensor modules  100  in the bus-type connection manner. 
         [0045]    In order to further save the power, as shown in  FIG. 4 , a switch  111  may be provided on the power supply line of the sensor unit  110 , and on and off states thereof may be switched by the enable signal, like the amplifier  121  having a disable function. In this case, the sensor unit  110  is configured to operate only at the enable state. The sensor signal input unit  205  is configured to record the output data when the state of the sensor unit  110  is stabilized. 
         [0046]    Also, as shown in  FIG. 5 , a plurality of sensor modules  100  may be unitized to configure a sensor module unit  300 , so that it is possible to easily treat a large amount of the sensor units  110 . In this case, since it is not necessary to make wirings between the respective sensor modules  100  in the sensor module unit  300 , it is possible to further reduce the complexity of the wirings while maintaining the basic configuration. 
         [0047]    In the meantime, the above descriptions are just to indicate the specific favorable exemplary embodiments so as to illustrate and exemplify the present invention. Therefore, the present invention is not limited to the above exemplary embodiments and includes more changes and modifications that can be made without departing from the gist of the present invention. In the meantime, the subject application is based on a Japanese Patent Application No. 2014-254629 filed on Dec. 17, 2014, which is entirely incorporated by reference. Also, all the references referred to herein are incorporated in its entirety. 
       DESCRIPTION OF REFERENCE NUMERALS 
       [0048]      10  . . . data collection system,  100  . . . sensor module,  110  . . . sensor unit  111  . . . switch,  120  . . . signal switching unit,  121  . . . amplifier having disable function  122  . . . D-type flip-flop,  200  . . . data collection apparatus,  201  . . . clock output unit  202  . . . enable signal output unit,  203  . . . counter,  204  . . . enable signal input unit  205  . . . sensor signal input unit,  206  . . . sensor managing table  210  . . . power supply unit,  300  . . . sensor module unit