JPH09233153A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct data communication between normal stations by matching a transmission speed with an optimum transmission speed in response to a state of a network. SOLUTION: In the case of revising a data transmission speed, a master station M sends a transmission speed revision command to slave stations S1-Sn. Then the master set regards slave stations not returning a transmission speed revision response within a prescribed condition to be not in existence and sends a transmission speed revision execution command only to slave stations returning the transmission speed revision command to revise the transmission speed and revises the transmission speed of itself and makes data communication only with slave stations with the transmission speed response. Furthermore, when the slave stations returning the transmission speed revision response do not receive the transmission speed revision execution command from the master station after a prescribed time, the slave stations revise the transmission speed based on the transmission speed information included in the transmission speed revision command.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system for performing data communication between a master station and a plurality of slave stations by a command / response method while changing the data transmission rate.

[0002]

2. Description of the Related Art Conventionally, in a network system in which data communication is performed between a master station and a plurality of slave stations, the data transmission rate on the network is set by the following method, for example. Was there.

A first method is a method in which a user fixedly sets a hardware switch or a software switch using a non-volatile memory or the like.

As a second method, there is a method of supplying the transmission clock of one communication station to the other transmission clock in order to automatically set the transmission rate of the transmission / reception station (for example, Japanese Patent Laid-Open No. 6-334706). No.

Further, as a third method, when the transmission / reception stations have independent transmission clocks and operate based on the transmission clocks, the transmission rate is automatically set. There is a method of changing the transmission rate by transmitting and receiving the data (for example, the actual Kaihei 5-1
1595 gazette).

[0006]

However, in the first method described above, the transmission rate once set is fixed. Therefore, for example, when a transmission error frequently occurs due to noise or the like, the transmission error continues. Happened,
There is a problem that the transmission efficiency is greatly reduced or the communication is stopped.

Further, when the user sets the transmission rate fixedly, it is difficult to match the maximum transmission rate that can be realized by the network because the types of the transmission rate that can be selected by the user are limited. There was also a problem that the settings were made and efficient data communication could not be performed.

In the second method, there is a problem that the communication transmission line increases by transmitting the transmission clock, and the cost increases as the transmission distance increases.

Further, in the third method, the transmission rate is changed by transmitting and receiving the transmission rate change execution command. However, if the transmission rate change execution command itself causes a transmission error, the transmission rate cannot be changed. , There is a problem.

Therefore, the present invention has been made by paying attention to such a problem, and sets only the optimum transmission rate that can be realized by the network according to the network condition, and only with the normal communication station. It is an object to provide a network system capable of executing data communication.

[0011]

In order to achieve the above object, in the invention according to claim 1, a command / response system is used between the master station and a plurality of slave stations while changing the data transmission rate. In a network system configured to perform data communication, when changing the data transmission rate, the master station sends a transmission rate change command to each slave station and returns a transmission rate change response within a predetermined condition. It is considered that there is no slave station that does not exist, the transmission rate is changed only for the slave station that has the transmission rate change response, and the transmission rate of the local station is changed so that It is characterized by performing data communication only in.

According to a second aspect of the invention, in the network system according to the first aspect, the master station detects whether or not the normal response from each slave is normal during data communication with each slave station. If the normal rate of the normal response exceeds the predetermined value, the transmission rate up command is sent to each slave station as the transmission rate change command, while the abnormal rate of the normal response exceeds the predetermined value. In this case, a transmission rate down command is transmitted to each slave station as a transmission rate change command.

According to the third aspect of the invention, in the network system according to the first or second aspect, the predetermined condition for assuming that there is no slave station that does not return the transmission rate change response by the master station , If the transmission rate change command is sent to each slave station and there is no transmission rate change response within the predetermined time, the transmission rate change command is retransmitted and the transmission rate change response is received a predetermined number of times, and then the predetermined number of times. It is characterized in that the transmission rate change response is not received within the time.

According to a fourth aspect of the present invention, in the network system according to the first, second or third aspect, the master station transmits the transmission rate change command to each slave station, and the transmission rate to be changed. While transmitting the transmission speed change command including information to each slave station,
When changing the transmission rate to a slave station that has a transmission rate change response, the slave station that sent the transmission rate change execution command and returned the transmission rate change response receives the transmission rate change execution command The transmission rate of the own station is changed based on the transmission rate information in the transmission rate change command.

In a fifth aspect of the present invention, in the network system according to the fourth aspect, if the slave station that returns the transmission rate change response does not receive the transmission rate change execution command from the master station within a predetermined time, The transmission rate of the own station is changed based on the transmission rate information in the transmission rate change command.

Therefore, in the present invention, when changing the data transmission rate, the master station transmits the transmission rate change command to each slave station and does not return the transmission rate change response within the predetermined condition. It is considered that there is no slave station, and the transmission rate change execution command etc. is sent only to the slave station that has the transmission rate change response to change the transmission rate. Make data communication only with the slave station that has a speed change response.

As the transmission rate change command transmitted from the master station to the slave stations, for example, in data communication with each slave station, the normal ratio of the normal response from each slave exceeds a predetermined value. If it is, the transmission speed up command to increase the transmission speed
When the abnormal rate of the normal response exceeds a predetermined value, a transmission rate down command for reducing the transmission rate is issued.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a network system according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of an embodiment of a network system according to the present invention.

As shown in the figure, this network system is configured by connecting a master station M and n slave stations S1 to Sn forming a slave station group S via a communication transmission line C. .

The master station M transmits / receives data to / from each slave station S1 to Sn forming the slave station group S by a command / response method, and transmits / receives a transmission rate change command / response and a transmission rate change execution command. It is configured to change the transmission rates of the self management station M and the slave stations S1 to Sn.

The slave stations S1 to Sn perform normal data transmission / reception with the master station M by a command / response method, or receive a transmission rate change command or the like from the master station M to change the transmission rate. The master station M is configured so that it cannot be transmitted unless it receives any command from the master station M.

The master station M and the slave stations S1 to S1
The hardware configuration of Sn is the communication I connected to the communication transmission line C.
/ F, a communication processing unit that performs communication processing, and the like are well-known configurations, and therefore further description is omitted here.

Next, a change pattern for changing the data transmission rate between the master station and the slave station configured as described above will be described with reference to the drawings.

FIG. 2 shows a procedure for changing the transmission rate during normal transmission.

In the case of this normal transmission, the master station M
For the slave station group S composed of the slave stations S1 to Sn,
The slave stations S1 to Sn, which have transmitted the transmission speed change command by broadcast and have received the command, send back a transmission speed change response to the master station M, and the master station M receiving the response sends the transmission speed change command to the slave stations. This is a case where a transmission rate change execution command is transmitted to the group S, and then the transmission rate is changed in the master station M and the slave stations S1 to Sn.

FIG. 3 shows a transmission rate changing procedure in the case where the transmission rate changing command or the like is not normally notified once, but is normally notified by the retransmission.

That is, in FIG. 3, the transmission rate change command from the master station is not normally notified to a part of the slave station group, and the master station cannot receive the transmission rate change response from all slave stations. After the transmission of the speed change command, after a lapse of a predetermined time, the pattern A for resending the transmission speed change command and the transmission speed change response are not normally returned from all slave stations to the master station. A pattern B in which a transmission rate change command is retransmitted after a predetermined time has passed is shown.
For both patterns A and B, the case in which the transmission speed can be changed in the master station M and the slave stations S1 to Sn by the retransmission is normally transmitted within a predetermined time or a predetermined number of times as shown in the pattern C. ing.

FIG. 4 shows a transmission rate change pattern when the master station retransmits the transmission rate change command but cannot receive a transmission rate change response from any slave station.

In other words, in this case, the master station M sends the transmission rate change command to each slave station, but cannot receive the transmission rate change response from all the slave stations, and returns the transmission rate change response. The transmission rate change command is retransmitted many times for a predetermined time or a predetermined number of times to slave stations that do not come. But even if you resend
Since the transmission rate change response cannot be received from the slave station, it is assumed that the slave station that cannot receive the transmission rate change response does not exist on the network.
Other slave stations and master stations change the transmission speed and communicate.

FIG. 5 shows a transmission rate change pattern when the transmission rate change command can be transmitted from the master station to the slave station, but the transmission rate change execution command cannot be transmitted.

That is, the master station can transmit the transmission rate change command to the slave station and receive the transmission rate change response from the slave station, but cannot transmit the transmission rate change execution command. In this case, at the slave station, after receiving the transmission rate change command,
After a predetermined time, it is automatically changed to the transmission rate specified by the transmission rate change command.

Next, a data communication processing procedure in the master station and the slave station configured as described above will be described with reference to the drawings.

FIG. 6 shows a data communication processing procedure in the master station M.

First, in the master station M, when the other processing is completed and the data communication processing is started, the slave stations S1 to S1.
Send various commands to Sn (step 10
0) By receiving the response from each slave station (step 110), normal data communication is performed, and at the time of the data communication, it is determined whether the number of errors or the error frequency exceeds a predetermined value. (Step 1
20) It is determined whether the normal transmission amount or the normal transmission time exceeds a predetermined value (step 130).

During the data communication, the number of errors or the error frequency does not exceed the predetermined value (step 12
0 "No") and the normal transmission amount or the normal transmission time does not exceed the predetermined value (step 130 "N").
o ”), which means that the current data transmission speed is the optimum one, it is then judged whether or not the data transmission processing is completed (step 140), and if it is judged that the data transmission is not completed, (Step 140 “No”),
While repeating the processing of steps 100 to 130 to continue the data communication and communication state with the slave stations S1 to Sn, when it is determined that the data transmission is completed (step 140 “Yes”). Then, the data communication process ends.

On the other hand, in the data communication, when it is determined that the number of errors or the error frequency exceeds the predetermined value (step 120 “Yes”), the transmission is optimized in order to optimize the data transmission rate on the network. Since it is necessary to reduce the transmission speed, the master station M executes the transmission speed reduction processing shown in FIG. 7 (step 150).

In the data communication, if the normal transmission amount or the normal transmission time exceeds a predetermined value (step 1
30 “Yes”), the transmission rate needs to be increased in order to optimize the data transmission rate on the network, so the master station M executes the transmission rate down processing shown in FIG. 8 (step 160).

FIG. 7 shows in detail the data transmission speed down processing in the master station M in step 150 of FIG.

First, in this data transmission rate down processing, the master station M determines whether or not the current transmission rate is the minimum transmission rate (step 151), and the current transmission rate is the minimum transmission rate. If (Step 151 “Y
es ”), because the transmission speed cannot be reduced any further,
This transmission speed down processing is ended.

On the other hand, if the current transmission rate is not the minimum transmission rate (step 151 "Yes"), then it is determined whether or not a transmission rate down command has been transmitted by a predetermined number of times by simultaneous broadcast or the like. (Step 152) If the transmission rate down command has not been transmitted the predetermined number of times (step 152 “No”), then the transmission rate down command is similarly transmitted (step 153).

The transmission rate down command from the management station M includes information on the transmission rate to be changed. As a general rule, the slave station returns a transmission rate change response to the management station M. When the transmission rate change execution command is received from the management station M, the transmission rate down command is changed to the transmission rate indicated by the transmission rate information in the command.

After transmitting the transmission rate down command,
Until a predetermined time has passed (step 156 “No”),
The transmission rate change response to the command is received from each slave station (step 154), and it is determined whether the responses to the command have been received from all slave stations (step 155).

Here, as described with reference to FIG. 2, when the response can be received from all the slave stations during the period from the transmission of the transmission rate down command to the elapse of a predetermined time (step 156 “No”). (Step 155
"Yes"), which means that all the slave stations are normal, so a transmission rate change execution command is transmitted to all the slave stations (step 157), and then the own management station M
The transmission rate is reduced (step 158), and the transmission rate down processing ends.

On the other hand, if the response cannot be received from all the slave stations (step 155 "No") and a predetermined time has elapsed (step 156 "yes").
s "), the process returns to the above step 152 until the transmission speed down command is transmitted a predetermined number of times (step 152).
“No”), perform the processing from step 153 onward,
The transmission rate down command is transmitted to the slave station that does not return the response, and the transmission rate down response is received.

Then, steps 153 to 156
If it is determined in step 152 that the transmission rate down command has been transmitted a predetermined number of times (step 152 “Yes”), a certain slave station is sent to the slave station as described with reference to FIG. Therefore, no matter how many times the transmission rate down command is retransmitted, the transmission rate down response is not returned. Therefore, it is considered that there is no slave station without the transmission rate down response (step 159), and the transmission rate down response is returned. The transmission rate change execution command is transmitted only to the returned slave station (step 157), the transmission rate of the self management station M is reduced (step 158), and the transmission rate down processing is ended.

FIG. 8 shows in detail the data transmission rate increasing process in the master station M in step 160 of FIG.

The data transmission speed increasing process in the master station M is basically step 150 shown in detail in FIG.
8 is the same as the data transmission rate down processing in the master station M, and the transmission rate change command transmitted by the master station M by simultaneous broadcast or the like is the transmission rate down command in FIG. The only difference is that it is a transmission speed up command.

That is, in step 161 of FIG. 8, which corresponds to step 151 of FIG. 7, it is determined whether or not the maximum transmission rate is obtained instead of the minimum transmission rate, which corresponds to steps 152, 153 and 156 of FIG. Step 16 of FIG. 8
2, 163, 166, the transmission rate up command is transmitted instead of the transmission rate down command. In step 168 of FIG. 8, which corresponds to step 158 of FIG.
Since the transmission rate down processing of the own management station M is not performed but the up processing is performed, the flow of the entire processing is the same as the data transmission rate down processing shown in FIG. 7, except that the content of the transmission rate change command is different. Further description will be omitted.

Next, a data communication processing procedure in each of the slave stations S1 to Sn will be described.

FIG. 9 shows a data communication processing procedure in the slave stations S1 to Sn.

First, in the slave station M, when the other processing ends and the data communication processing starts and various commands are transmitted from the master station, the commands are received (step 200) and the received command is received. Is a transmission rate down command (step 210) and whether it is a transmission rate up command (step 22).
0).

If the received command is neither the transmission rate down command (step 210 "No") nor the transmission rate up command (step 220).
"No"), because it is a normal data communication command,
The data contained in the command is received (step 230), and a normal response is returned to the management station M (step 240).

On the other hand, when the received command is the transmission speed down command (step 210 "Yes"
s "), the slave station which has received the command executes the transmission rate down processing shown in FIG. 10 (step 260).

If the received command is a transmission rate increase command (step 220 "Yes"), the slave station that has received the command executes the transmission rate increase process shown in FIG. 11 (step 270).

After the above processing is completed, the slave station determines whether or not the data reception is completed (step 2).
50), if not completed (step 250 “N
o "), the process returns to the step 200 to repeat the above process, and if completed (step 250" Yes "
s "), the above data communication processing is ended.

FIG. 10 shows in detail the data transmission rate reduction processing in the slave station in step 260 of FIG.

In this data transmission rate down processing, the slave station that receives the transmission rate down command first sends a response to the master station (step 261), and then within a predetermined time, the master station M executes the transmission rate change. It is determined whether the command is received (steps 262, 26
3) If a transmission rate change execution command is received from the master station M within a predetermined time (step 263 “No”,
(Step 262 “Yes”), and based on the reception timing of the transmission rate change execution command, the transmission rate down processing of the own slave station is performed (step 264).

On the other hand, even when the transmission speed down command cannot be received from the master station M within the predetermined time (step 2
62 "Yes", step 263 "Yes"), the slave station itself performs the transmission rate down process based on the transmission rate information in the previously received transmission rate change command after the predetermined fixed time (step 264).

FIG. 11 shows in detail the data transmission rate increasing process in the slave station in step 270 of FIG.

The data transmission rate increasing process in the slave station is basically the same as the data transmission rate decreasing process in the slave station in step 260 shown in FIG. 10, and in the above-mentioned FIG. 10, the transmission from the master station M is performed. While the change command is the transmission rate down command, the difference in FIG. 11 is that it is the transmission rate up command.

That is, in step 271 corresponding to step 261 in FIG. 10, a response to the transmission rate up command is transmitted instead of the response to the transmission rate down command, and in step 274 corresponding to step 264 in FIG. The only difference is that the transmission rate of the slave station is not the transmission rate down processing but the up processing, and the overall flow of each processing is as shown in step 2 in FIG.
Since it is the same as the data transmission speed down processing of 60, further explanation is omitted.

Therefore, according to this embodiment, the master station M
When changing the data transmission rate, it is considered that there is no slave station that sends a transmission rate change command to each slave station and does not return the transmission rate change response within a predetermined condition such as a predetermined number of retransmissions. , A transmission rate change execution command is sent only to a slave station that has a transmission rate change response to change the transmission rate. Since the data communication is performed only between the slave stations, the management station M can always perform the data communication only with the normal slave station at the optimum transmission rate according to the state of the network.

When the present embodiment is compared with the above-mentioned three methods of the prior art, the present embodiment has the following effect differences.

That is, as compared with the first method of the prior art, when a transmission error frequently occurs due to noise or the like, according to the present embodiment, the transmission rate is automatically reset to a transmission rate at which the transmission error does not occur. By doing so, it is possible to avoid transmission errors and improve transmission efficiency, and because the management station can dynamically set the optimum transmission rate that can avoid communication interruption due to transmission errors, the types of transmission rates that can be set are This is much higher than the setting of the transmission speed by SW or the like. That is, according to the present embodiment, since the transmission rate is set more finely than the first method of the conventional technique, the transmission rate of the communication station can be adjusted to the maximum or optimum transmission rate that can be realized in the network. It is possible to make better use of the performance of the communication station.

Further, as compared with the second method of the prior art, a communication line for transmitting a clock is not required in the communication transmission line connecting the stations, so that the longer the transmission distance is, the more advantageous the cost becomes.

Further, as compared with the third method of the prior art, both of them are common in that the slave station changes the transmission rate by receiving the transmission rate change execution command, but in the present embodiment, the transmission is changed. Even if the speed change command causes a transmission error, there is an advantage that the slave station itself can change the transmission speed based on the transmission speed information in the transmission speed change command.

[0068]

As described above, according to the present invention, when the master station changes the data transmission rate, it transmits a transmission rate change command to each slave station and returns a transmission rate change response within a predetermined condition. It is considered that there is no slave station that does not come, and the transmission rate change execution command etc. is sent only to the slave station with the transmission rate change response to change the transmission rate, and the transmission rate of the own station is changed. Since the data communication is performed only with the slave station that has the transmission speed change response, the management station always performs the data communication only with the normal slave station at the optimal transmission speed according to the network status. It can be carried out.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of an embodiment of a network system according to the present invention.

FIG. 2 is an explanatory diagram showing a transmission rate changing process during normal transmission.

FIG. 3 is an explanatory diagram showing a transmission rate change process when a transmission rate change command or the like is normally notified by retransmission.

FIG. 4 is an explanatory diagram showing a transmission rate change process when a transmission rate change response cannot be received from a slave station even if a transmission rate change command is retransmitted.

FIG. 5 is an explanatory diagram showing a transmission rate change process when a transmission rate change execution command cannot be transmitted.

FIG. 6 is a flowchart showing a data communication processing procedure in the master station.

FIG. 7 is a flowchart showing in detail a data transmission speed down process in the master station.

FIG. 8 is a flowchart showing in detail a data transmission speed increasing process in the master station.

FIG. 9 is a flowchart showing a data communication processing procedure in a slave station.

FIG. 10 is a flowchart showing in detail a data transmission speed down process in a slave station.

FIG. 11 is a flowchart showing in detail a data transmission speed increasing process in a slave station.

[Explanation of symbols]

 M Master station S1 to Sn Slave station C Communication transmission line

Claims (5)

[Claims] 1. In a network system configured to perform data communication between a master station and a plurality of slave stations by a command / response method while changing the data transmission rate, the master station sets the data transmission rate. To change the transmission rate, send a transmission rate change command to each slave station and consider that there is no slave station that does not return the transmission rate change response within the specified conditions. The network system is characterized in that the transmission rate is changed only for that station, the transmission rate of the local station is changed, and data communication is performed only with a slave station that has a response to change the transmission rate. 2. The master station detects whether or not the normal response from each slave is normal during data communication with each slave station, and the normal ratio of the normal response exceeds a predetermined value. In this case, the transmission rate up command is transmitted to each slave station as the transmission rate change command, while if the abnormal rate of the normal response exceeds a predetermined value, the transmission rate down command is sent as the transmission rate change command. The network system according to claim 1, wherein the network system transmits the slave station. 3. The predetermined condition when the master station regards a slave station that does not return a transmission speed change response as nonexistent is that a transmission speed change command is transmitted to each slave station and transmission is performed within a predetermined time. When there is no speed change response, the transmission speed change command is retransmitted and the transmission speed change response is received a predetermined number of times, and the transmission speed change response is not received within the predetermined number of times. The network system according to claim 1 or 2. 4. The master station, when transmitting a transmission rate change command to each slave station, transmits a transmission rate change command including transmission rate information to be changed to each slave station, and at the same time transmits a transmission rate change response. When changing the transmission rate to a certain slave station, the slave station that sent the transmission rate change execution command and returned the transmission rate change response will receive the transmission rate change execution command The network system according to claim 1, 2 or 3, wherein the transmission rate of the local station is changed based on the transmission rate information. 5. When the slave station which has returned the transmission rate change response does not receive the transmission rate change execution command from the master station within a predetermined time, the slave station determines its own station based on the transmission rate information in the transmission rate change command. The network system according to claim 4, wherein the transmission rate is changed.