JPH11234297A - Radio network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease resending processing by maintaining a stable line state, resulting in shortening of response time. SOLUTION: Before cyclically exchanging data with a slave station 12, a master station 11 detects the state of a line with the slave station 12 and when the slave station 12 does not have the stable line state as a result, the subscription/release information of the relevant slave station in a slave status table is made into non-subscription but when the slave station has a prescribed line state, the subscription information of the slave station is made into subscription. Thus, in the case of refreshing an I/O with the slave station 12, it is performed based on the subscription/release information in the slave status table so that the stable line state can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio network system for transmitting and receiving data between a master station and a slave station cyclically via a radio line.

[0002]

2. Description of the Related Art In recent years, wireless network systems have been introduced at manufacturing sites for the following reasons and are becoming more widespread. With the increasing demand for computerization at the manufacturing site, there is a need for wireless networking of programmable logic controllers, CNCs, robot controllers, etc. There is a need to reduce construction work With the frequent addition of lines or layout changes, There is a demand to reduce costs. It is difficult to lay communication cables due to equipment with limited moving bodies, rotating bodies, and moving parts. The above-mentioned wireless network system requires high-speed processing to increase production efficiency. As well as being required, it was necessary to have high transmission reliability.

[0003] As described above, the wireless network system has come into widespread use in manufacturing sites in recent years.
This is due to the spread spectrum communication system and the progress of error correction technology.

[0004] As a wireless network system at a manufacturing site, for example, there is one as shown in FIG.

[0005] This wireless network system includes a programmable controller 50 as a remote I / O master station.
And a master station 51 as a management station are connected to a remote I / O network 60 on a wired transmission path, and
The master station 51 and the slave station 52 are configured to transmit data wirelessly.

[0006] Further, this wireless network system includes:
Generally, a polling / selecting method that can guarantee the data transmission time is used as the protocol used. When the network is started, each master station 51 registers the registration table in the registration table. In addition to registering the slave station 52 to be added, if the slave station 52 cannot communicate for some reason, the registration of the slave is deleted from the registration table.

In such a wireless network system, unlike the case of the wired network, the line condition between the master station 51 and the slave station 52 is not uniform due to, for example, radio wave interference and distance by a worker at the work site.

For example, the master station 51 and WIND are "1".
Communication between the master station 51 and the WI is small because the distance between the slave stations 52 is short and the line condition is stable.
Since the distance between the slave stations 52 whose ND is "2" is long and the line condition is unstable, a communication error sometimes occurs.

[0009]

As described above, in a wireless network system at a manufacturing site, the line conditions between the master station 51 and the slave station 52 are not all stable, so that the line conditions are unstable. When the slave station 52 is joined to the network, many packet errors occur during data transmission, and the retransmission process accompanying the error must be repeated, so that the communication response time becomes longer.

[0010] As described above, when the line condition between the specific slave stations 52 is unstable, the master station 51 consequently transmits all the slave stations that have joined the network within a predetermined cycle time. 52, unable to communicate with
The PLC 50 has a problem that it is not possible to normally control a device to be controlled at a manufacturing site.

In particular, in a conventional wireless network system at a manufacturing site, even if the line condition with the master station 51 is unstable, there is almost no effect, for example, communication between the slave stations 52 of a display device for displaying the number of products produced. Since it is necessary to always maintain a stable state as a system,
As described above, the processing of the entire system is affected by the influence of the line state of the slave station 52, which hardly affects the system at the manufacturing site.

Accordingly, the present invention has been made in view of the above problems,
An object of the present invention is to provide a wireless network system that aims to reduce retransmission processing by maintaining a stable state as a system and, as a result, shorten response time.

[0013]

According to a first aspect of the present invention, there is provided a master station and a slave station connected to the master station by a radio line.
In a wireless network system for cyclically transmitting and receiving data between the master station and the slave station, the master station detects a line state between the slave stations before cyclically transmitting and receiving data to and from the slave station. After that, data is transmitted / received to / from a slave station having a predetermined line state.

[0014] According to a second aspect of the present invention, in the first aspect of the invention, the master station does not start cyclic data transmission / reception unless a slave station which must be subscribed is not subscribed. I do.

The third aspect of the present invention provides the first or second aspect.
In the invention described in the above, the master station has subscription information storage means for storing subscription information indicating whether the slave station is subscribed to the network or not, and between the slave stations. Before cyclically transmitting and receiving data, a line state detecting means for detecting a line state between the slave stations, and the line state detecting means, when the slave station does not have a predetermined line state, Subscription information registering means for registering the subscription information of the slave station in the information storage means as unsubscribed, while having a predetermined line condition, subscribing the subscription information of the slave station. When data is transmitted and received cyclically between data, data is transmitted and received based on the subscription information stored in the subscription information storage means.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the line state detecting means transmits a subscription invitation command of a predetermined total number of transmittable transmissions to the slave station to the slave station. Transmit to the station, if the response to it is equal to or more than the allowed number consisting of a predetermined number, it is detected that the line state is stable, if less than the allowed number, the line state is unstable Is detected.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the master station cyclically transmits and receives data even when the slave station leaves the network, and the master station is disconnected from the slave station. Non-priority information that permits re-joining of a slave station, and first priority information that cyclically transmits and receives data to and from other slave stations even if the slave station leaves, but does not allow re-joining of the slave station that has left. And, after the slave station leaves, the post-leaving processing information storage means having second priority information for stopping the transmission and reception of the cyclic data is provided, and when the slave station leaves, Then, processing based on the post-leaving processing information storage means is performed.

According to the present invention, before the master station cyclically transmits / receives data to / from the slave stations, it detects the line state between the slave stations and then transmits / receives data to / from the slave station having a predetermined line state. Therefore, data can be transmitted in a stable state as a system.

Further, after the data is cyclically transmitted and received between the master station and the slave station, when the slave station leaves, the subsequent data transmission and reception are performed based on the post-leave processing information storage means. Therefore, when the line of the slave station having little influence on the line is unstable, the slave station can be disconnected from the network and maintained in a stable line state.

In particular, as a system, the master station stops the system when a slave station that does not operate properly unless it has joined the system is stopped, and starts cyclic data transmission and reception when the slave station has not joined the system. In order to prevent such a situation, abnormal operation of the entire system can be prevented.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wireless network system according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment of the wireless network system according to the present invention.

The wireless network system of this embodiment is a system in which a wired communication LAN adopting a polling / selecting system for cyclic polling as a protocol and a wireless LAN adopting the same protocol are connected by a gateway. As shown in FIG. 1, a host PLC 10 connected to a remote I / O network 13 which is a wired communication LAN, and a plurality of master stations 11 as gateways connected to the remote I / O network 13 and the wireless communication LAN. And a plurality of slave stations 12 for transmitting and receiving I / O data to and from a predetermined master station 11 by wireless communication.

In the wireless network system of this embodiment, as shown in FIG. 2, data (I / O information) is repeatedly transmitted and received between a master station 11 and a slave station 12 within a predetermined time (cycle time). (I / O refresh). In one communication cycle, the master station 11 periodically (cyclically) polls each slave station 12 for a cyclic communication phase and peripheral processing. It has a notification phase for performing processing.

In the cyclic communication phase, the master station 11 transmits to the slave station 12 a command including a subscription invitation command, initial data read / write, and cyclic data read / write.
As shown in FIG. 3, a command transmitted to the slave station 12 and a response to the command are managed as one slot.

Further, each master station 11 constituting the wireless network system according to this embodiment has an I
“WNID” as D has # 0 and has “WGID” as ID indicating a channel.

Each slave station 12 also has "WGID" as an ID indicating a channel and "WNID" specifying a station.

Incidentally, the master station 11 shown at A in FIG.
Is “1” as “WGID” and “WNID”
(All the master stations have “0”), and the slave station 12 shown in B of FIG.
It has “1” as “GID” and “1” as “WNID”.

Next, each component constituting the wireless network system of this embodiment will be described.

The host PLC 10 controls devices to be controlled such as sensors and motors.
In a memory (not shown) such as the above, a subscription registration slave table 101 in which subscription invitation information indicating whether or not to invite subscription to the wireless network system for the slave station 12 managed by each master station 11 is registered. Have.

This subscription registration slave table 101 is
When the wireless network system is started up, it is downloaded to the master station 11 and is formed in advance by the user.

When the flag of “0” is registered, the invitation invitation information indicates that the slave station 12 is invited to join, and when the flag of “1” is registered. Indicates that the corresponding slave station 12 is not invited to join.

By the way, the subscription registration slave table 101 shown in FIG. 4 indicates that the master station 12 having a WIND of "1" to "32" for performing wireless communication with the master station 11 on a certain channel.
Has registered subscription solicitation information.

The master station 11 transmits and receives I / O data in order to perform I / O refresh between the slave stations 12 in a spread spectrum system. The master station 11 has a subscription registration slave table 111 and a slave status table. 112 and a priority station setting table 113.

The subscription slave table 111 is formed by downloading the subscription slave table 101 provided in the host PLC 10 when the wireless network system is started, that is, when the master station 11 is powered on.

This subscription registration slave table 111 is
This is necessary for the master station 11 to make an initial subscription invitation to the slave station 12 under management. The configuration is the same as that of the registered slave table 101 described above.

The slave status table 112 indicates that the master station 11 makes an initial subscription invitation to the slave station 12 under management using the subscription registration slave table 111, and thereafter, the slave station 12 under management becomes Is for the master station 11 to solicit a subscription.

The slave status table 112 has R
It is formed in a volatile memory (not shown) such as AM,
It registers registration / withdrawal information indicating whether the slave station 12 managed by the master station 11 has subscribed to the wireless network system or has left (including non-subscribed).

If the flag of "1" is registered in the joining / leaving information, it indicates that the corresponding slave station 12 has joined the wireless network system.
When the flag of “0” is registered, it indicates that the corresponding slave station 12 has left the wireless network system.

Incidentally, the slave status table 112 shown in FIG.
The ND registers the information of joining / leaving with the master station 12 of “1” to “32”.

The priority station setting table 113 indicates that the master station 1
Information defining the processing operation when I / O refresh is performed on the slave station 12 under the control of 1 (described later)
As shown in FIG. 6, each slave station 12 has attribute information at the time of joining (described later) and attribute information at the time of leaving (described later).

The attribute information at the time of joining is information indicating whether or not the master station 11 can shift to the I / O refresh after the start of the wireless network system. , "1"
(Priority) or “0” (non-priority).

More specifically, when all the slave stations 12 whose attribute information at the time of joining in the priority station setting table 113 is registered as "1" (priority) have all joined, the I / O refresh is performed to the master station 11 for the first time. Is performed.

Therefore, if the slave station 12 whose entry attribute information registered in the priority station setting table 113 is “1” does not join the wireless network system, the master station 11 will 12 is not subjected to I / O refresh.

If the slave station 12 whose entry attribute information registered in the priority station setting table 113 is “1” has joined the wireless network system, the master station 11 temporarily stores the priority station setting table. Even if there is non-priority join-time attribute information in 113, I / O refresh is not performed except for this non-priority slave station 12.

The leaving attribute information is information indicating a process (to be described later) that can be performed when the slave station 12 managed by the master station 11 leaves the wireless network system, and a flag of “0” is registered. When the flag is set, the level is set to 1. When the flag of "1" is registered, the level is set to 2.

The master station 12 has a priority station setting table 11
3 based on the attribute information at the time of joining and attribute information at the time of withdrawal
The following processing is performed.

That is, if the attribute information at the time of joining of the slave station 2 is non-priority (“0”), the master station 11 restarts the slave station 12 while continuing the I / O refresh. They are allowed to join.

-1 The master station 11 continues the I / O refresh if the attribute information at the time of joining of the slave station 2 has priority ("1") and the attribute information at the time of leaving is at level 1. At the same time, the slave station 12 that has left is not rejoined.

-2 The master station 11 stops the I / O refresh when the attribute information at the time of joining has priority ("1") and the attribute information at the time of leaving is level 2. I have.

Then, in this state, the master station 11
In order to return to the normal state without accepting the communication request, it is necessary to turn on the power again and reset the hardware.

Next, each slave station 1 performed by the master station 11
2 will be described.

After the radio network system is started, the master station 11 transmits a subscription invitation command for a predetermined number of times to the slave station 12, and when a response to the command is received for the predetermined number of times or more, the slave station 12
Is determined to be permitted to join the wireless network system, and a flag of “1” is registered in the joining / leaving information of the corresponding portion of the slave status table 112, while “other” is added to the joining / leaving information in other cases. The flag "0" is registered.

Here, the joining process performed by the master station 11 to each slave station 12 will be specifically described with reference to FIGS.

In the joining process shown in FIG. 7, the total number of transmission of the subscription invitation command is set to six, and when the number of permitted subscriptions is obtained four times, the master station 11 becomes the corresponding slave station 12.
Is an example in which the subscription is permitted, and the subscription process shown in FIG.
In this example, the total number of transmissions of the subscription invitation command is six, and if the number of permitted subscriptions is not obtained four times, the master station 11 has a criterion for disallowing the slave station 12 from subscribing.

(1) Regarding the case where the subscription in the case shown in FIG. 7 is permitted In this case, in the slots # 1, # 2, # 3 and # 6, the subscription invitation command transmitted to the predetermined slave station 12 In order to receive a response (ACK) to the slave station 12, if the number of permitted transmissions of the slave station 12 has been obtained four times out of the six numbers of transmissions of the above-described invitation request command, the slave station 12 satisfies the criterion of permission to subscribe.

(2) When the subscription is permitted in the case shown in FIG. 8 In this case, the response (ACK) to the subscription invitation command is received only in the slots # 1 and # 2, Already 3 for slots 4 and # 5
Time, a response could not be obtained, and therefore, it is not necessary to transmit a subscription invitation command in the slot # 6, and the permission criterion for the subscription of the slave station 12 is not satisfied.

Note that the master station 11 transmits a subscription permission command when the response to the subscription invitation command reaches the permitted number, and upon receiving the response to the command, the slave station table 112 registers the corresponding information in the slave status table 112. May be registered as a "1" flag.

Further, the master station 11, for example, sets the total number of transmissions of the subscription invitation command that can be transmitted in advance to A, sets the total number of transmissions of the subscription invitation command until now to B times, If the number of responses of C is set to C and the number of registrations permitted in the slave status table 112 is set to D, it is determined that registration in the slave status table 112 is not permitted when AB−C <D, and the slave status table A flag of “0” may be registered in the joining / leaving information of the corresponding part 112.

It should be noted that the total transmission number A of the above-described subscription invitation command and the number D of times permitted to register in the slave status table 112 can be set differently for each slave station 12. It goes without saying that it is good.

The slave station 12 keeps the master station 1
If no command has been received from No. 1, it is determined that the own station has left.

The master station 11 performs a retry method for each of the above-mentioned commands, and determines that the slave station has left when the retry is out.

The slave station 12 researches the master station 11 having a receivable channel at the time of start-up and at the time of judging withdrawal from the subscription. As a result, when an arbitrary command is received, the slave station 12 locks the channel and subscribes. Wait for it to be done. Hereinafter, the operation of the wireless network system will be described as (1) a processing operation from execution of an initialization process to execution of an I / O refresh, and (2) a case where the slave station 12 is disconnected during a cyclic communication phase. The operation will be described separately.

(1) Processing Operation from Performing Initialization Processing to Performing I / O Refresh FIG. 9 and FIG. 10 are flowcharts showing processing from performing initialization processing to performing I / O refresh. is there.

When the power of the PLC 10 and the slave station 12 is turned on and the wireless network system is started up, the master station 11 sends the subscription registration slave table 111, slave status table 112, and priority station setting table 1
13 is initialized (step 110).

Next, the master station 11 downloads the registration slave table 101 included in the PLC 10 to the registration slave table 111. Thereafter, the master station reads out the subscription invitation information in which the WIND of the subscription registration slave table 111 is “n” (step 120),
It is determined whether or not the slave station 12 whose WIND corresponds to "n" is registered (step 130).

When the master station 11 determines that the slave station 12 corresponding to WIND of “n” has been registered (step 130; Yes), the master station 11 sends a subscription invitation command to the slave station 12 as described above. As described above, the data is transmitted a predetermined number of times (within the range) (step 140).
30; No), the routine goes to Step 170.

When the master station 11 transmits the subscription invitation command to the slave station 12 a predetermined number of times, the master station 11 determines whether or not the number of permitted subscriptions among the transmitted subscription invitation commands has reached the above-mentioned permitted number of subscriptions. It is determined whether or not there is a normal response (step 150). If it is determined that there is a normal response (step 150;
Yes), the joining / leaving information having the flag of "1" is registered in the corresponding portion of the slave status table (step 160). On the other hand, when it is determined that there is no normal response (step 150; No), the corresponding Subscription information with a "0" flag in the location is registered (step 165).

Subsequently, the master station 11 determines whether or not the subscription solicitation information in which the WIND of the read subscription registration slave table 111 is “n” is n = 32 (step 1).
70), if it is determined that the subscription invitation information of “n” is not n = 32 (Step 170; No), a value n + 1 obtained by adding 1 to n is set to a new n (Step 175), and the process proceeds to Step 120. Then, the same processing as described above is performed.
When it is determined that the subscription invitation information of “n” is n = 32 (Step 170; No), it is determined whether all the registered priority setting slaves have already subscribed (Step 180).

If the master station 11 determines that all of the registered priority setting slaves are not subscribed (step 180; No), the priority setting registered in the registered slave table 111 but not yet subscribed is performed. A subscription invitation poll is transmitted to the slave, and a response (AC
K) is checked and the slave status table 11 is checked.
2 is updated (step 185).

On the other hand, when the master station 11 determines that all the registered priority setting slaves have already subscribed (step 180; Yes), the master station 11 thereafter enters the cyclic communication phase and enters the slave status table 112.
, An I / O refresh is performed on the slave station 12 (step 190), and an initialization process is performed to execute the I / O refresh.
The processing up to the execution of the refresh ends.

(2) Processing when Slave Station 12 Leaves During Cyclic Communication Phase FIG. 11 is a flowchart showing processing when slave station leaves during the cyclic communication phase.

If the master station 11 does not receive a response to a certain number of polling invitations to a certain slave station 12 even after performing a predetermined number of polling invitations, the master station 11 determines that the slave station 12 has left the wireless network system. , The following removal processing is performed.

The master station 11 has a priority station setting table 11
3, it is determined whether or not the detached slave station 12 is a priority station (step 210). As a result, if it is determined that the detached slave station 12 is a priority station (step 210; Yes) ), Then this slave station 1
It is determined whether or not the level 2 is level 1 (step 220).

The master station 11 is connected to the slave station 12
Is determined not to be level 1 (step 22).
0; No), and stop the I / O refresh processing (stop the execution of the cyclic communication phase) (step 24)
0), when it is determined that the level of the leaving slave station 12 is level 1 (step 220; Yes), the slave status table 112 and the priority station setting table 1
Then, the registration of the corresponding slave station 12 is deleted from the node 13 and the leaving process is terminated.

The master station 11 thereafter cancels the I / O refresh processing for the slave station 12 whose registration has been deleted from the slave status table 112.

In the wireless radio network system of this embodiment, before the master station 11 cyclically transmits and receives data to and from the slave stations 12, the line state between the slave stations 12 is detected. Does not have a predetermined line state, the subscription information of the slave station in the slave status table 112 is unsubscribed. On the other hand, if the terminal has a predetermined line state, the subscription information of the slave station is By doing so, the I / O refresh between the slave stations 12 is performed based on the subscription information of the slave status table 112, so that a stable line state can be maintained.
Retransmission processing can be reduced, and response time can be shortened.

When the slave station leaves after starting the I / O refresh between the master station 11 and the slave station 12, based on the joining attribute information and the leaving attribute information in the priority station setting table 113, In order to transmit and receive data thereafter, when the line of the slave station 12 having little effect on the line is unstable, the slave station 12
Can be disconnected from the network to keep the system stable.

[0079]

As described above, according to the present invention, before the master station cyclically transmits / receives data to / from the slave stations, the line state between the slave stations is detected, and then the slave station having a predetermined line state is detected. Since data is transmitted and received in a stable manner, a stable line state can be maintained. As a result, retransmission processing can be reduced and response time can be shortened.

Further, when the slave station leaves after cyclically transmitting and receiving data between the master station and the slave station, based on the post-leaving processing information storage means,
In order to transmit and receive data thereafter, when the line of a slave station that has little effect on the line is unstable, the slave station can be disconnected from the network and maintained in a stable state as a system.

Further, if the slave station which does not operate normally unless the master station is always joined as a system leaves, the system is stopped when the slave station leaves, and cyclic data transmission / reception is started if the slave station is not joined. In order to prevent such a situation, abnormal operation of the entire system can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a wireless network system according to the present invention.

FIG. 2 is an explanatory diagram for explaining data transmission and reception between a master station and a slave station in FIG. 1;

FIG. 3 is an explanatory diagram of a cyclic communication phase in FIG. 2;

FIG. 4 is a block diagram showing a configuration of a registered slave table.

FIG. 5 is a block diagram showing a configuration of a slave status table.

FIG. 6 is a block diagram showing a configuration of a priority station setting table.

FIG. 7 is an explanatory diagram for explaining how a slave station determines whether to join a wireless network system.

FIG. 8 is an explanatory diagram for explaining how a slave station determines whether to join a wireless network system.

FIG. 9 is a flowchart showing a process from performing an initialization process to executing an I / O refresh.

FIG. 10 is a flowchart showing a process from performing an initialization process to executing an I / O refresh.

FIG. 11 is a flowchart illustrating processing when a slave station leaves during a cyclic communication phase.

FIG. 12 is a schematic configuration diagram showing a configuration of a conventional wireless network system.

[Explanation of symbols]

 10 Program Logic Controller 101 Subscription Registration Slave Table 11 Master Station 111 Subscription Registration Slave Table 112 Slave Status Table 113 Priority Station Setting Table 12 Slave Station 13 Remote I / O Network

Claims (5)

[Claims] 1. A wireless network system comprising: a master station; and a slave station connected to the master station via a wireless line. The wireless network system cyclically transmits and receives data between the master station and the slave station. Wirelessly transmitting and receiving data to and from a slave station having a predetermined line state after detecting a line state between the slave stations before cyclically transmitting and receiving data to and from the slave station. Network system. 2. The wireless network system according to claim 1, wherein the master station does not start cyclic data transmission / reception unless a slave station that requires subscription is not subscribed. 3. The master station comprises: subscription information storage means for storing subscription information indicating whether the slave station is subscribed to the network or not; and between the slave stations. Before cyclically transmitting and receiving data, a line state detecting means for detecting a line state between the slave stations; and if the slave station does not have a predetermined line state, Subscription information registering means for registering the subscription information of the slave station in the information storage means as unsubscribed, while having a predetermined line condition, subscribing to the subscription information of the slave station; 2. The data transmission / reception system according to claim 1, wherein, when data is transmitted and received cyclically, data is transmitted and received based on subscription information stored in said subscription information storage means. Network system. 4. The line state detecting means transmits to the slave station a subscription invitation command of a predetermined total number of transmittable transmissions to the slave station, and a response to the command is a predetermined number of responses. 4. The wireless communication system according to claim 3, wherein when the number is equal to or more than the number, the line state is detected to be stable, and when the number is less than the permitted number, the line state is detected to be unstable. Network system. 5. The non-priority information for cyclically transmitting and receiving data even when the slave station leaves the network and permitting the rejoined slave station to rejoin, the master station comprising: Even if the slave station leaves, data is transmitted and received cyclically to other slave stations, but the first priority information that does not permit re-joining of the slave station that has left, and when the slave station leaves, the cyclic data And second priority information for stopping the transmission and reception of the post-leaving processing information storing means having the following. When the slave station has left, processing based on the post-leaving processing information storing means is performed. 5. The wireless network system according to claim 1, wherein: