JP2006093967A - Network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network system which sends/receives data at mutually synchronized timings of a plurality of communications apparatus network to the network, and can reduce the traffic using a simple constitution. <P>SOLUTION: The system comprises communications apparatuses 1, 2, 3 each being communicatingly connected to a bus 4, having an internal timer 8 for counting the time. Any one of the communication apparatus sends a token contained in time information to other communications apparatus, the receiver of the communications apparatus receiving the own-addressed token actuates the internal timer 8 to count the synchronization time shown by the time information contained in the received token, and adds a specified process time to the synchronous time to send a token, contained in the time information showing the added time, to other communications apparatus, when the internal timer 8 counts the lapse of the synchronization time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a network system including a plurality of communication devices that transmit and receive data.

Conventionally, as a network system that performs synchronization processing between each of a plurality of communication devices, a reference device that transmits a synchronization reference packet by broadcast at a fixed period based on an internal timer, and a reception timing of the synchronization reference packet from the reference device A device that operates by resetting the internal timer is configured to be connected to a LAN that uses token passing, and the internal reference timer of another connected device is connected to the internal timer of the reference device by this synchronization reference packet. (For example, refer to Patent Document 1).
JP 2000-134241 A

  However, in the above network system, since the reference device transmits the synchronization reference packet so that the internal timer of the reference device and the internal timer of the other connected device are synchronized, it is necessary to install the reference device, Another problem is that network traffic increases because the synchronization reference packet is broadcast at regular intervals.

  The present invention has been made in order to solve the conventional problems. A plurality of communication devices connected to a network can transmit and receive data at the same timing, and can reduce traffic with a simple configuration. An object of the present invention is to provide a network system that can be used.

  The network system of the present invention includes a plurality of communication devices that are connected to be communicable with a network and have time measuring means for measuring time, and any one of the plurality of communication devices includes time information. A receiving device that transmits a token to another communication device and receives the token addressed to itself receives the synchronization time indicated by the time information included in the received token by the receiving device, and the time measuring device When the elapsed time of the synchronization time is counted, the predetermined processing time of the receiving device is added to the synchronization time, and a token including time information indicating the added time is transmitted to another communication device. ing.

  With this configuration, each communication device transmits and receives data at the same time by transmitting a token including time information indicating the time when the receiving device adds a predetermined processing time. Installation is unnecessary, and the network system can be configured simply. Further, since the token is not broadcast at regular intervals, traffic can be reduced.

  Further, in the network system of the present invention, when the time measuring unit measures the lapse of time and the receiving device transmits data, the receiving device transmits a transmission processing time and a predetermined time when transmitting the data. Is added to the synchronization time, and a token including time information representing the added time is transmitted to another communication device.

  With this configuration, even when the receiving device transmits data, the transmission processing time is added to the synchronization time in addition to the predetermined processing time, and the token is transmitted to other communication devices. Data can be transmitted and received without impairing data.

  Further, in the network system of the present invention, the time measured by each of the time measuring means is initialized every predetermined cycle, and when the added time has passed the cycle, the receiving device And a token including time information indicating the corrected time is transmitted to another communication device.

  With this configuration, when the time to be timed is initialized for each predetermined cycle, when the added time has passed the cycle, the time added by the receiving device is corrected, and time information indicating the corrected time is included. Since the token is transmitted to another communication device, data can be transmitted / received without losing the synchronization timing in each communication device.

  In the network system according to the present invention, the transmission processing time is calculated based on a data amount and a data transfer rate when the data is transmitted.

  With this configuration, since the transmission processing time is calculated based on the data amount and the data transfer rate, it is possible to cope with the case where the data amount to be transmitted to other communication devices is variable.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a network system in which a plurality of communication devices connected to a network can transmit and receive data at the same timing, and can reduce traffic with a simple configuration.

  Hereinafter, a network system according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a block diagram of a network system according to the first embodiment of the present invention. The network system 10 according to the first embodiment of the present invention has a configuration in which a communication device 1, a communication device 2, and a communication device 3 are connected to a bus 4 so as to be communicable. The network system 10 has a network configuration when applied to an ARCNET (Attached Resource Computer NETwork) of an improved token passing LAN. In the network system 10 shown in FIG. 1, three communication devices are illustrated, but the number is not limited to three, and a large number of communication devices may be provided.

  The communication device 1, the communication device 2, and the communication device 3 are provided with an internal timer 8 that measures time. The internal timers 8 of the communication device 1, the communication device 2, and the communication device 3 are shown as an internal timer 8a, an internal timer 8b, and an internal timer 8c, respectively. In addition, each communication device includes a network interface for communicating with a device connected on the network, a CPU (Central Processing Unit) for executing a program, and the like. Note that the processing related to the internal timer 8 and the processing performed by the communication device may function as a program.

  As illustrated in FIG. 1, for example, the communication device 1 transmits a token 12 including time information to each of the other communication devices. Information indicating the address of the communication device 2 is added to the token 12 when the communication device 1 transmits, and time t2 is set in the time information. The token is a signal representing the right for data transmission, and the communication device that has received the token has the right to transmit data to other communication devices via the bus 4. The time indicated by the time information included in the token is referred to as a synchronization time.

  Of the communication devices that have received the token 12, the communication device 2 that has received the token 12 addressed to itself causes the internal timer 8b to count the synchronization time t2. Thereafter, when the communication device 2 does not transmit data and the internal timer 8b times the synchronization time t2, the communication device 2 includes time information indicating a time obtained by adding a predetermined processing time to the synchronization time t2. The token 22 to be transmitted is transmitted to another communication device. Information indicating the address of the communication device 3 is added to the token 22 when the communication device 2 transmits.

  Hereinafter, processing of the network system according to the first embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a time chart showing the relationship of data transmission / reception timing in each communication device. In FIG. 2, the communication device 1 and the communication device 2 do not have data to be transmitted, only the communication device 3 has data to be transmitted to the communication device 1, and the communication device 3 has the communication device 1. A state of transmitting data is shown. The period T is a period for synchronizing the internal timer 8a, the internal timer 8b, and the internal timer 8c, and the time measured by each internal timer 8 is initialized every period T.

  First, the communication device 1 has time information indicating time t2 obtained by adding the time t1 that is the transmission timing of the token 12 and the processing time Tt from when the token 12 is transmitted until the communication device 2 starts a response. The included token 12 is transmitted to another communication device. Note that information indicating the address of the communication device 2 is added to the token 12.

  Next, the communication device 2 and the communication device 3 that have received the token 12 cause the internal timer 8 to count the synchronization time t2 included in the received token 12. At this time, the communication device 2 determines that the token 12 is addressed to itself and there is no data to be transmitted to another communication device. Thereafter, when the internal timer 8b measures the elapse of the synchronization time t2, the communication device 2 transmits a token 22 including time information representing the time t3 obtained by adding the processing time Tt to the synchronization time t2 to another communication device. . Note that information indicating the address of the communication device 3 is added to the token 22.

  Next, the communication device 1 and the communication device 3 that have received the token 22 cause the respective internal timers 8 to count the synchronization time t3. At this time, the communication device 3 transmits data to the communication device 1 in order to determine that the token 22 is addressed to itself and has data to be transmitted to the communication device 1.

  By the way, in order to transmit and receive data, it may be necessary to follow a series of procedures in accordance with a communication standard such as ARCNET. As a series of procedures, as shown in FIG. 2, a signal FBE for inquiring whether or not the buffer of the destination communication device is empty is transmitted from the source communication device to the destination communication device, and the signal FBE is transmitted. Is transmitted from the transmission destination communication device to the transmission source communication device, a signal PAC for transmitting data is transmitted from the transmission source communication device to the transmission destination communication device, and a response to the signal PAC. The signal ACK is transmitted from the transmission destination communication device to the transmission source communication device.

  Further, the communication device 3 calculates a time t4 that is a time obtained by adding the transmission processing time Td and the processing time Tt required for data transmission to the synchronization time t3. However, since the time t4 is equal to or greater than the period T, the communication device 3 obtains the time t4 by the equation (1), corrects the time t4, and transmits the token 32 including the time information indicating the corrected time t4 to other communication. Send to device.

(Equation 1)
t4 = t3 + Td + Tt−T (1)
Information indicating the address of the communication device 1 is added to the token 32 transmitted by the communication device 3. The data transmission timing in the network system 10 is synchronized by circulating the token between the communication devices. In the first embodiment, the amount of data to be transmitted is constant, and each communication device may prepare in advance the value of the transmission processing time Td as a constant. Each communication device may prepare in advance the value of the processing time Tt as a constant.

  FIG. 3 is a flowchart showing processing performed by each communication device according to the first embodiment of the present invention.

  First, when a token is received by the communication device (S1), the synchronization time is measured by the internal timer 8 (S2), and it is determined whether the received token is addressed to itself (S3). If it is determined that it is not addressed to itself, it waits for the reception of the token again. If it is determined that it is addressed to itself, it is determined whether there is data to be transmitted to another communication device (S4).

  If there is no data to be transmitted, it is determined whether or not the value obtained by adding the processing time Tt to the synchronization time is equal to or greater than the value of the cycle T (S6). If the value does not exceed the value of the period T, the processing time Tt is added to the synchronization time, and time information indicating the time obtained by the addition is set in the token (S9). When the value is equal to or greater than the value of the period T, the processing time Tt is added to the synchronization time, the period T is subtracted from the time obtained by the addition, and time information indicating the time obtained by the subtraction is set in the token. (S10). At this time, the token for which the time information is set is transmitted to another communication device (S12).

  If there is data to be transmitted, it is determined whether or not the value obtained by adding the processing time Tt and the transmission processing time Td to the synchronization time is equal to or greater than the value of the cycle T (S5). If the value of the period T is not exceeded, the processing time Tt and the transmission processing time Td are added to the synchronization time, and time information indicating the time obtained by the addition is set in the token (S7). Time information indicating the time obtained by adding the processing time Tt and the transmission processing time Td to the synchronization time, subtracting the period T from the time obtained by the addition, and subtracting when the value is equal to or greater than the value of the period T Is set as a token (S8). At this time, data is transmitted to a specific communication device (S11). After the data transmission, the token in which the time information is set is transmitted to another communication device (S12).

  As described above, in the network system according to the first embodiment of the present invention, the time information indicating the time when the communication device that has received the token (hereinafter referred to as a receiving device) adds a predetermined processing time is provided. By transmitting the included token, each communication device transmits and receives data at the same timing, so that it is not necessary to install a reference device, and the network system can be simplified. Further, since the token is not broadcast at regular intervals, traffic can be reduced.

  Even when the receiving device transmits data, the transmission processing time is added to the synchronization time in addition to the predetermined processing time, and the token is transmitted to other communication devices. Data can be transmitted and received without loss.

  In addition, when the time to be timed is initialized every predetermined cycle, when the added time has passed the cycle, the time added by the receiving device is corrected, and a token including time information indicating the corrected time is included. Since data is transmitted to other communication devices, data can be transmitted / received without losing the synchronization timing of each communication device.

(Second Embodiment)
FIG. 4 shows a block configuration diagram of a network system according to the second embodiment of the present invention. In the first embodiment, the amount of data to be transmitted is constant, but in the second embodiment, a network system that enables transmission and reception of an arbitrary amount of data will be described.

  The network system 20 according to the second embodiment of the present invention has a configuration in which the communication device 5, the communication device 6, and the communication device 7 are communicably connected to the bus 4. The network system 20 has a network configuration when applied to an improved token-passing LAN ARCNET (Attached Resource Computer NETwork). In the network system 20 shown in FIG. 4, three communication devices are illustrated, but the number is not limited to three, and a large number of communication devices may be provided.

  Of the components constituting the network system according to the second embodiment of the present invention, the same components as those constituting the network system according to the first embodiment of the present invention are the same. Reference numerals are assigned and explanations thereof are omitted. In addition, the communication device 5, the communication device 6, and the communication device 7 include an internal timer 8 that measures time. The internal timers 8 of the communication device 5, the communication device 6, and the communication device 7 are shown as an internal timer 8d, an internal timer 8e, and an internal timer 8f, respectively.

  As shown in FIG. 4, for example, the communication device 5 is configured such that the internal timer 8d measures the elapse of the synchronization time t5 and transmits the token 42 including the time information to each of the other communication devices. Information indicating the address of the communication device 6 and time information are added to the token 42 when the communication device 5 transmits.

  Hereinafter, processing of the network system according to the second embodiment of the present invention will be described with reference to the drawings.

  FIG. 5 is a time chart showing the relationship of data transmission / reception timing in each communication device. In FIG. 5, the communication device 6 and the communication device 7 do not have data to be transmitted, only the communication device 5 has data to be transmitted to the communication device 7, and the communication device 5 has the communication device 7. A state of transmitting data is shown.

  First, when the communication device 5 receives the token addressed to itself and determines that it has data to be transmitted to the communication device 7, it calculates a transmission processing time Td. Here, a time Tfbe related to the transmission of the signal FBE, a time Tack related to the transmission of the response signal ACK, a time td related to the transmission of the signal PAC, and a time tp from the completion of the data transmission to the reception of the response signal ACK, The transmission processing time Td is expressed by equation (2). The time Tfbe, the time Tack, and the time tp are constants specific to the network.

(Equation 2)
Td = Tfbe + Tack + td + tp + Tack (2)
Further, assuming that the transfer rate S, which is a network-specific constant, and the data amount n at the time of transmission, time td is expressed by equation (3). In this embodiment, the unit of the transfer rate S is bps, and the unit of the data amount n is bit.

(Equation 3)
td = n / S (3)
In addition, the communication device 5 calculates a time t6 that is a time obtained by adding the calculated transmission processing time Td and the processing time Tt to the time t5. However, since the time t6 is larger than the period T, the communication device 5 obtains the time t6 by the equation (4), corrects the time t6, and transfers the token 42 including the time information indicating the corrected time t6 to other communication. Send to device.

(Equation 4)
t6 = t5 + Td + Tt−T (4)
FIG. 6 is a flowchart showing processing performed by each communication device according to the second embodiment of the present invention. Of the processing performed by each communication device according to the second embodiment of the present invention, the same processing as that performed by each communication device according to the first embodiment of the present invention is denoted by the same reference numeral. Each description is omitted.

  If it is determined that the received token is addressed to itself, it is determined whether there is data to be transmitted to another communication device (S4). When there is data to be transmitted, the transmission processing time Td is calculated based on the data amount and the data transfer speed when transmitting the data (S20), and processed at the calculated transmission processing time Td and the synchronization time. It is determined whether the value obtained by adding the time Tt is equal to or greater than the value of the period T (S5).

  As described above, since the network processing system according to the second embodiment of the present invention calculates the transmission processing time based on the data amount and the data transfer rate, the data to be transmitted to other communication devices. Even when the amount is variable, it can be handled.

  As described above, the network system according to the present invention has an effect that a plurality of communication devices connected to the network can transmit and receive data at the same timing, and can reduce traffic with a simple configuration. It is useful as a network system that includes a plurality of communication devices that transmit and receive data.

The block block diagram of the network system which concerns on the 1st Embodiment of this invention The time chart which showed the relationship of the timing of the data transmission / reception in each communication apparatus which concerns on the 1st Embodiment of this invention The flowchart which shows the process which each communication apparatus which concerns on the 1st Embodiment of this invention performs. The block block diagram of the network system which concerns on the 2nd Embodiment of this invention The time chart which showed the relationship of the timing of the data transmission / reception in each communication apparatus which concerns on the 2nd Embodiment of this invention The flowchart which shows the process which each communication apparatus which concerns on the 2nd Embodiment of this invention performs.

Explanation of symbols

1, 2, 3, 5, 6, 7 Communication device 4 Bus 8, 8a, 8b, 8c, 8d, 8e, 8f Internal timer (time measuring means)
10, 20 Network system 12, 22, 32, 42 tokens

Claims (4)

A plurality of communication devices connected to a network so as to be communicable and having time measuring means for measuring time;
Any one of the plurality of communication devices transmits a token including time information to another communication device,
Causing the time measuring means to count the synchronization time indicated by the time information included in the received token of the receiving device that is the communication device that has received the token addressed to itself,
When the time of the synchronization time has elapsed, the time measuring unit adds a predetermined processing time of the receiving device to the synchronization time, and transmits a token including time information indicating the added time to another communication device. A network system characterized by this. When the time measuring means time elapses and the receiving device transmits data,
The receiving device adds a transmission processing time and a predetermined processing time when transmitting the data to the synchronization time, and transmits a token including time information indicating the added time to another communication device. The network system according to claim 1. The time measured by each of the time measuring means is initialized every predetermined cycle, and when the added time has passed the cycle,
The network system according to claim 1, wherein the receiving device corrects the added time and transmits a token including time information indicating the corrected time to another communication device. The network system according to any one of claims 1 to 3, wherein the transmission processing time is calculated based on a data amount and a data transfer speed when the data is transmitted.

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