JP2007251712A - Radio communication system and data collection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce probability that communication is disabled due to obstacles or the like. <P>SOLUTION: A polling radio apparatus 1 performs radio communication with respective radio slave units 2(2-1 to 2-7) in a polling method. For example, in communication with the radio slave unit 2-1, the polling radio apparatus 1 makes the radio salve unit 2-1 as a destination, and transmits data whose relaying destination is the radio slave unit 2-3 (1). The radio slave unit 2-3 which has received the data performs repeat transmission of the received data (2). The communication is performed through two communication routes such as these direct communication route and relay route. Even when the obstacle is place on one communication route to disable the communication, the communication is not necessarily disabled because there is the other communication route. In addition, responses of the radio slave unit 2-1 are returned through the same communication routes ((3), (4)). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polling wireless communication system and a data collection method thereof.

  For example, in various facilities such as factories, etc., each access point (for example, each production line) is connected to one access point (wireless master unit connected to a cable) and each device constituting the production line. There is a case in which a wireless communication system that is configured to include a plurality of wireless slave devices that perform communication by a polling method is installed.

  Using this polling wireless communication system, for example, at a predetermined cycle, the access point wireless master device polls a plurality of other wireless slave devices at high speed, and is connected to these wireless slave devices. Collect the information that occurs. Then, the collected information is sent to, for example, a server device that manages the entire factory via the wire, and centralized management / processing is performed. In addition to collecting information, a command such as a work instruction / setting change may be sent from the server device side. Alternatively, remote control of the production line is also performed. Therefore, in the following description, the case where the wireless communication system functions as a wireless data collection system will be described as an example, but the present invention is not limited to this.

FIG. 10 is a diagram illustrating an example of a configuration of a conventional wireless communication system.
In the figure, a polling wireless device 51 is a wireless master device having a function of polling a plurality of wireless slave devices 52-1 to 52-7 and collecting information.

  Each of the wireless slave units 52-1 to 52-7 is connected to, for example, various devices (for example, a programmable controller, a control personal computer, etc.) constituting the production line. In these various devices, some information is generated at an arbitrary timing. Each of the wireless slave units 52-1 to 52-7 has a function of returning such information in response to polling from the polling wireless device 51.

  The polling wireless device 51 is connected to the wired communication path 53, and the information collected by the polling wireless device 51 is sent to a server device (not shown) via the wired communication path 53 and managed / processed. . The wired communication path 53 does not have to be a wired communication path in particular, and represents a means for using collected information.

Next, an example of the polling procedure will be described with reference to FIG.
First, the polling wireless device 51 transmits a command for requesting information to the wireless slave device 52-1 (a). The wireless slave device 52-1 returns the latest information in response to the request command from the polling wireless device 51 (b). Subsequently, similar communication is performed for the wireless slave unit 52-2 (c) and (d). The state of this communication is shown in FIG. Subsequently, the same communication is sequentially performed for the wireless slave units 52-3 to 52-7. By repeating this periodically, the latest information can always be collected.

  By the way, wireless communication may be disconnected due to the influence of surrounding obstacles. FIG. 12 shows this state. FIG. 12 shows a state in which a request command from the polling wireless device 51 to the wireless slave device 52-1 is blocked by the shield 54 and does not reach the wireless slave device 52-1. Due to the failure of the request command, the polling wireless device 51 cannot obtain information from the wireless slave device 52-1, and this state continues as long as the shielding object 54 exists.

  The problem of the present invention is that, in a system in which the access point wireless master unit communicates with each wireless slave unit by polling, the probability of occurrence of an inability to communicate due to an obstacle or the like can be significantly reduced, and even when communication is disabled It is to provide a wireless communication system capable of flexible communication.

  The wireless communication system according to the present invention includes a wireless master device at an access point and a plurality of wireless slave devices, and the wireless communication system performs communication between the wireless master device and each wireless slave device by a polling method. Each communication between the parent device and each wireless slave device is performed by direct communication between the wireless slave device to be communicated and the wireless master device, and indirectly using a wireless slave device other than the wireless slave device to be communicated as a relay device. This is performed by two communication routes, such as simple communication.

  By having two communication routes in this way, even if one communication route becomes disabled due to an obstacle, etc., there is another communication route. The probability of communication failure is significantly reduced.

  In the wireless communication system, for example, data transmitted by the wireless master device or each wireless slave device includes at least information for identifying a transmission destination and a wireless slave device to which the data is to be relayed. Each wireless slave unit that receives the message repeats transmission of the received data to the transmission destination when it is determined that the own unit is a relay unit based on the identification information.

  In addition, the wireless communication system includes, for example, a table that indicates, for each wireless slave unit, candidates for wireless slave units that should be relayed when communicating with the wireless slave unit with priority. And when the wireless master unit selects a wireless slave unit as a repeater each time from among the plurality of candidates, and neither of the two communication routes can be communicated in communication by the selected relay unit Then, change the repeater based on the table and retry.

In this way, even if both of the above two communication routes are disabled, it is possible to flexibly change the relay route.
Furthermore, the above table is for a combination of the wireless master device and all the wireless slave devices at any time after system installation and / or operation start, except for the wireless slave device to be communicated for each combination. Created / updated based on the result of a communication test using all wireless slave units as repeaters.

  Thus, since the relay route is determined based on the result of the actual communication test at each installation site, it is possible to set a highly reliable relay route that matches the actual situation of the site. Furthermore, if it is performed not only at the time of system installation but also at an arbitrary timing after the start of operation, it is possible to cope with changes in the environment of the actual site.

  Furthermore, the wireless slave device that can be a candidate for the relay device is, on the condition that the success rate of communication relayed by the wireless slave device is a predetermined threshold or more as a result of the communication test, or The condition is that there is little correlation between the failure of direct communication with the wireless slave device to be communicated and the failure of communication via the relay device, or both of these two conditions are satisfied.

  The data collection method according to the present invention comprises a wireless master device at an access point and a plurality of wireless slave devices, and the wireless master device periodically and sequentially polls each wireless slave device. A data collection method in which a wireless slave device returns information on a device connected to the wireless slave device to the wireless master device, wherein the wireless master device transmits an information request command to each wireless slave device. The transmission information is transmitted by adding the identification information of the transmission destination wireless slave device and the identification information of the wireless slave device serving as the relay device, and the wireless slave device serving as the relay device transmits the received request command to the transmission destination wireless slave device. The transmission-destination wireless slave device that has transmitted the request repeatedly from the wireless slave device that has been used as the wireless master device and / or the relay device transmits the information on the device connected to the own device to the relay device. The returned wireless slave unit is used as a repeater again and sent back to the wireless master unit.

  According to the wireless communication system of the present invention, it is possible to provide a system having a very low probability of being unable to communicate due to an obstacle or the like and having high communication reliability. It is possible to provide a system that can respond by switching the repeater.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 and FIG. 2 show an example of the configuration of the wireless communication system of the present embodiment and its polling procedure.

  In the following description, the case where the wireless communication system functions as a wireless data collection system in a factory or the like will be described as an example. However, the present invention is not limited to this. As described above, for example, there is a form in which a command such as a work instruction / setting change is sent from the server device side, a case where it is used for remote control of a production line, or the like. Of course, the application destination is not limited to a factory or the like.

  In FIG. 1, a polling wireless device 1 is a wireless master device having a function of polling a plurality of wireless slave devices 2 (2-1 to 2-7) and collecting information. The polling wireless device 1 is connected to the wired communication path 3, and information collected by the polling wireless device 1 is sent to a server device (not shown) via the wired communication path 3 for management / processing and the like. . The wired communication path 3 is not particularly limited to the configuration of the wired communication path, but represents a means for using the collected information.

  Each of the wireless slave units 2-1 to 2-7 is connected to, for example, various devices (for example, a programmable controller, a control personal computer, etc.) constituting the production line. In these various devices, some information is generated at an arbitrary timing. Each of the wireless slave devices 2-1 to 2-7 has a function of returning these information in response to polling from the polling wireless device 1.

  In FIG. 1, the polling wireless device 1 is basically communicable with all the wireless slave devices 2 (wireless slave devices 2-1 to 2-7) (of course, when there are obstacles, etc.). In addition, each of the wireless slave devices 2-1 to 2-7 can communicate with at least one other wireless slave device.

  The polling wireless device 1 polls the wireless slave devices 2-1 to 2-7. That is, the polling wireless device 1 sequentially transmits, for example, a request command for causing the wireless slave devices 2-1 to 2-7 to send the latest information. The requested wireless slave returns the requested information. At that time, there is a communication route for directly transmitting / replying data by a question between the polling wireless device 1 and the requested wireless slave device, and a communication route for relaying this data by other wireless slave devices.

In order to explain this in detail, reference is first made to FIG. 3 which shows an example of the data format of a request command transmitted from the polling radio 1 or reply data corresponding thereto.
The request command / reply data 10 (hereinafter simply referred to as “communication data”) shown in the figure has fields of destination 11, relay radio device 12, and command / data 13. The destination 11 stores destination data (for example, an ID unique to each wireless device) indicating the wireless slave device to which the communication data is transmitted. For example, in the case of transmission of a request command, any one of the wireless slave devices 2-1 to 2-7 is a destination, and in the case of a reply to this, the polling wireless device 1 is a destination. The relay wireless device 12 stores data (for example, the ID) indicating the wireless slave device that should relay this communication data. The command / data 13 includes the request command when the communication data is transmitted from the polling wireless device 1, and the requested information when the communication data is a reply to the command (data of the device to which the own device is connected). Information, etc.) are stored.

  The wireless slave device that has received this performs incoming call processing when the destination 11 is its own device. When the relay radio device 12 is its own device, the same information is repeatedly transmitted at the next evening time. When the repeater repeats, a code indicating that it is invalid (hereinafter referred to as invalid code) is stored in the field of the relay radio 12. Thus, for example, the wireless slave device that has received the request command addressed to its own device refers to the field of the relay wireless device 12, and if the invalid code is not stored in the field of the relay wireless device 12, this is the polling wireless device. It is determined that the communication data transmitted from the device 1 is directly received, and the wireless slave device 2 designated as the relay device waits for a repeat time. When the communication data transmitted by the relay device is received (or even if it cannot be received due to an obstacle or the like), response information is returned at the next timing.

  The designation of the relay radio is determined by the polling radio 1 (detailed determination method will be described later). Further, the destination wireless slave device 2 stores the information stored in the field of the relay wireless device 12 for transmission data by the polling wireless device 1 as it is in the field of the relay wireless device 12 for reply data. That is, even when the destination wireless slave unit 2 replies, the same wireless slave unit 2 is relayed.

Note that “repeat” means that the same information is transmitted again, and is a nuance that serves as both retransmission and relay.
Returning to FIGS. 1 and 2 again, here, the polling wireless device 1 will be described in more detail by taking as an example a case where a request command to the wireless slave device 2-1 is transmitted. In this example, it is assumed that the wireless slave unit 2-3 is designated as a relay unit. A method for determining the repeater will be described later.

  Each wireless slave device that has received this request command refers to the destination 11 and the relay wireless device 12 of this request command, and does nothing if it is neither the destination nor the relay destination. Here, the wireless slave units 2-2 and 2-4 to 2-7 do not receive or do nothing even if they are received.

  The wireless slave device 2-1 and the wireless slave device 2-3 each receive the request command (1). The wireless slave device 2-1 recognizes that the request command has been sent to its own device by referring to the destination 11 of the received request command and the relay wireless device 12, and still transmits from the relay device. Will not be answered yet at the next timing.

  The wireless slave unit 2-3 refers to the destination 11 of the received request command and the relay wireless unit 12 to recognize that the own unit is designated as the relay unit of the request command, and at the next timing (2), The same request command (however, an invalid code is stored in the field of relay wireless device 12) is transmitted to wireless slave device 2-1. The wireless slave device 2-1 also receives this request command.

  At the next timing (3), the wireless slave device 2-1 transmits (replies) information on a response to the request command. This reply data is received by the polling wireless device 1 and the wireless slave device 2-3.

  Further, at the next timing (4), the wireless slave unit 2-3 communicates communication data of the same information as that transmitted by the wireless slave unit 2-1 (however, an invalid code is stored in the field of the relay wireless unit 12). Send. The polling wireless device 1 receives this communication data.

  The polling wireless device 1 can collect information on all wireless slave devices 2 by repeating the above processing for all wireless slave devices 2. FIG. 2 shows the operation of FIG. 1 in a timing diagram.

  Even if the request command relayed by the repeater (wireless handset 2-3) cannot be received at the timing (2), the reply process is performed at the next timing (3). Further, when a request command relayed by the repeater (wireless handset 2-3) is received first (that is, direct communication data from the polling wireless device 1 cannot be received for some reason) ), The reply process is performed at the next timing without waiting.

  As described above, in the wireless communication system of this example, when communication is not interrupted due to a change in the surrounding environment, an obstruction, or the like, the polling wireless device 1 and the destination wireless slave device 2 are mutually connected. In addition to receiving communication data directly from the other party, you will receive the same communication data from the repeater, but it is not saying that both are necessary, but either one of them depends on obstacles etc. Even if the communication route is interrupted, the communication route can be normally communicated with the other communication route.

For example, a case where an obstacle occurs will be described with reference to FIG.
FIG. 4 shows a state in which a shield 4 is generated between the polling wireless device 1 and the wireless slave device 2-1, and communication between the polling wireless device 1 and the wireless slave device 2-1 is interrupted. Show.

  In this situation, when the polling wireless device 1 transmits a request command to the wireless slave device 2-1 at a certain timing (1), this request command is received by the wireless slave device 2-3, but is wireless because of the shielding object. The slave unit 2-1 fails to receive.

  At the next timing (2), the wireless slave unit 2-3 transmits the received request command repeatedly. This request command is received by the wireless slave device 2-1. In response to the request command received from the wireless slave unit 2-3, the wireless slave unit 2-1 transmits response information at the next timing (3) (in this case, the invalid code is stored. Do not wait at the next time). This reply data is received by the wireless slave unit 2-3, but the polling wireless device 1 cannot receive it due to the influence of the shield 4.

  Then, at the next timing (4), the wireless slave unit 2-3 repeatedly transmits the communication data returned by the wireless slave unit 2-1. Since this communication data can be received by the polling wireless device 1, the data collection from the wireless slave device 2-1 is completed, and the same processing is sequentially performed for the wireless slave devices 2-1 to 2-7. Will continue.

  In the above description, the wireless slave device 2-1 can receive the communication data relayed by the wireless slave device 2-3, but there may be a situation in which it cannot be received. In consideration of such a case, the polling radio device 1 may determine / change the relay device as described below.

FIG. 5 shows an example of a table for the polling radio 1 to determine a relay radio.
The table 20 shown in the figure stores information indicating which wireless slave device is appropriate as a relay wireless device for all destinations.

  In the figure, for example, for the wireless slave device 2-1, the wireless slave device 2-4, the wireless slave device 2-6, and the wireless slave device 2-7 are x, that is, not suitable as a relay wireless device (relay wireless device). It is not a candidate for a machine). The numbers in the table 20 indicate the priority order when selecting as a relay radio. When polling radio 1 fails, polling is performed for the number of retries while changing relay radios in order of priority, and if polling is successful, polling is performed for the next destination.

An example of such processing is shown in the PAD diagram of FIG.
In the PAD diagram of FIG. 6, step S <b> 1 indicates that the process is looped by the number of wireless slave units. That is, first, the target wireless slave device (destination) is determined (step S2), and the number of retries set in the table 20 for the destination wireless slave device (that is, the candidate is a candidate (× No) (only for the number of wireless devices), the process of steps S4 to S6 is looped (step S3). As described above, a polling process is performed in which relay radio devices are designated in order from the highest priority and relayed by this relay radio device. If the polling is successful (step S6, yes), the processing related to this destination is completed (step S7), and the same processing is performed while changing the destination wireless slave device (step S2). If polling fails, polling is performed for the maximum number of retries while changing the relay radio (step S4).

  In the example shown in the figure, when polling fails, the same wireless slave unit is retried, and after completion, the next destination wireless slave unit is polled, but the other wireless slave units are polled first. You may make it.

  FIG. 7 shows information 30 for the polling radio device 1 to determine the priority order of the relay radio devices. In the figure, the information 30 seems to be embedded only in the cell 20 in the table 20 where the destination is the combination of the wireless slave unit 2-7 and the relay is the wireless slave unit 2-6. Of course, each information 30 is embedded for every other combination.

The information 30 includes the total number N of polling times when the specific wireless slave device is the destination and the other specific wireless slave device is the relay wireless device, and the number of successful polling by the relay (for direct communication success / failure). Regardless, the number of successful relays) p, and the number of failed times q for both direct communication to the destination and communication relayed to the relay radio. The determination as to whether or not the relay radio can be selected is determined by the following conditions 1) and 2), or the logical product (AND) conditions of 1) and 2).
1) p / N exceeds the first threshold.
2) q / (Np) is below the second threshold.

That is, 1) is based on the condition that the success rate by relay when a fixed relay wireless device is used for a specific wireless slave device exceeds a first threshold value that is arbitrarily set in advance.
2) is based on the condition that there is little correlation between failure due to direct communication with the wireless slave device and failure of communication via the relay wireless device. That is, since (Np) directly means the number of times both of the relays have failed, q / (Np) means that both the relay and the direct fail for the number of times the relay has failed. It means the ratio (probability) of the number of times. Here, since it is sufficient that either one of direct / relay succeeds in polling, it is better that the probability of failure of both direct and relay is small. Therefore, it is a condition that this falls below a second threshold value that is arbitrarily set in advance.

A wireless device that satisfies one or both of the conditions 1) and 2) is determined as a candidate for a relay wireless device.
Furthermore, it is assumed that, from among the wireless devices that are candidates for the relay wireless device as described above, the one having the highest p / N is assigned the highest priority.

In order to collect the information shown in FIG. 7, dedicated polling is performed at the time of system installation, at the time of system installation and at regular intervals thereafter, or at an arbitrary timing.
A PAD diagram of dedicated polling processing is shown in FIG.

  In the PAD diagram shown in the figure, the “dedicated polling process” tries all wireless slave devices as relay wireless devices for the wireless slave devices of the destination while sequentially setting all wireless slave devices as destinations. The above process (that is, the process from step S12 to S18) is tried a preset number of times (M times) (step S11).

  Step S12 indicates that the processing of steps S14 to S18 is looped by the number of slave units while changing the destination wireless device (step S13). Step S14 is to repeat the processing of steps S17 and S18 while changing the relay radio (step S15) (however, the destination radio is not a relay radio (step S16) as a condition), that is, polling processing And repeat the process of counting the communication results.

Then, based on the result of such “dedicated polling processing”, that is, the total count result, the priority order as the relay radio is determined based on the above-described determination criteria.
As described above, according to the wireless communication system of the present invention, it is possible to provide a system having high communication reliability. Such effects become more prominent as the number of wireless slaves that can be relayed increases, as will be described below with specific examples.

  That is, for example, in FIG. 9, assuming that the probability of successful communication of all wireless devices in the area indicated by the ellipse 40 is 0.9, in the communication between the polling wireless device 1 and the wireless slave device 2-1, the polling wireless The probability that the wireless slave device 2-1 can communicate with the wireless slave device 2-1 by relaying any wireless slave device 2-A from the device 1 is 0.9 × 0.9 = 0.81. Similarly, since the probability of being able to communicate via any wireless slave unit 2-B is 0.81, the probability of being able to communicate using either the wireless slave unit 2-A or the wireless slave unit 2-B is: (1- (1-0.81) × (1-0.81)) = 0.9639. As the number of wireless devices that can be relayed in this way increases, the communication reliability becomes extremely high.

An example of the configuration of the wireless communication system of this embodiment and its polling procedure is shown. An example of a polling procedure corresponding to the example of FIG. 1 is shown. It is a figure which shows an example of the data format of communication data. An example of a situation where communication is interrupted by a shielding object is shown. An example of the table for a polling radio | wireless machine to determine a relay radio | wireless machine is shown. FIG. 6 is a PAD diagram showing an example of communication processing using the table of FIG. 5. The information for a polling radio | wireless machine determining the priority of a relay radio | wireless machine is shown. FIG. 8 is a PAD showing an example of a dedicated polling process for collecting the information of FIG. 7. It is a figure for demonstrating concretely that a communication success probability improves by this invention. It is a figure which shows an example of a structure of the conventional radio | wireless communications system. An example of a polling procedure corresponding to the example of FIG. 10 is shown. An example of a situation where communication is interrupted by a shielding object is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polling radio | wireless machine 2 (2-1 to 2-7) Wireless cordless handset 3 Wired communication path 4 Shield 10 Request command / reply data (communication data)
11 Destination 12 Relay wireless device 13 Command / data 20 Table 30 Information 40 Ellipse

Claims (6)

In a wireless communication system consisting of a wireless master device at an access point and a plurality of wireless slave devices, in which communication between the wireless master device and each wireless slave device is performed by a polling method,
For each communication between the wireless master device and each wireless slave device, direct communication between the wireless slave device to be communicated and the wireless master device, and a wireless slave device other than the wireless slave device to be communicated as a relay device A wireless communication system, which is performed by two communication routes, indirect communication. The data transmitted by the wireless master device or each wireless slave device includes at least information for identifying a transmission destination and a wireless slave device to which the data is to be relayed,
2. The wireless slave device that receives the data repeats transmission of the received data to the transmission destination when the wireless device determines that the wireless device is a relay device based on the identification information. Wireless communication system.   The wireless master unit maintains a table showing, with priority, wireless slave unit candidates to be relayed when communicating with the wireless slave unit for each wireless slave unit. When a wireless slave device to be used as a relay device is selected from among the candidates, and neither of the two communication routes is communicable in communication by the selected relay device, the relay device is changed based on the table. The wireless communication system according to claim 1 or 2, wherein retry is performed.   The table includes all wireless devices other than the wireless slave device to be communicated for each combination with respect to the combination of the wireless master device and all the wireless slave devices at any timing after system installation and / or operation start. 4. The wireless communication system according to claim 3, wherein the wireless communication system is created / updated on the basis of a result of a communication test using the communication device as a relay device.   The wireless slave device that can be a candidate for the relay device is based on the condition that the success rate of communication relayed by the wireless slave device is equal to or higher than a predetermined threshold as a result of the communication test, or the wireless master device and its communication target The condition is that there is little correlation between the failure of direct communication with the wireless slave device and the failure of communication via the relay device, or both of these two conditions are satisfied. 4. The wireless communication system according to 4. It consists of a wireless master device at the access point and a plurality of wireless slave devices. The wireless master device periodically polls each wireless slave device sequentially, and each wireless slave device connects to its own device. A data collection method for returning information on the device to the wireless master unit,
When transmitting the information request command to each wireless slave device, the wireless master device adds the identification information of the destination wireless slave device and the identification information of the wireless slave device to be used as a relay device. ,
The wireless slave unit that is set as a repeater repeats the received request command to the destination wireless slave unit,
The destination wireless slave device that has received the request command from the wireless slave device that has been designated as the wireless master device or / and the relay device transmits the information on the device connected to the own device to the wireless slave device that has been designated as the relay device. As a repeater, and a reply to the wireless master device.

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