JP2000134241A - Token passing protocol type lan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify wiring equipment and to effectively utilize conventional equipment by performing a synchronous processing with an error within token cyclic time without separately providing a synchronizing signal line. SOLUTION: When a synchronization reference packet 10 and a data packet for communication are successively sent out from reference equipment 1 in a cycle T to the other equipment 2 and 3 as needed, the equipment 2 and 3 start the measurement of reception elapsed time at the timing of completing reception for all the packets. In the case of judging that the reception packet is the synchronization reference packet, the sum of the reception elapsed time at the point of time and the reception time of the synchronization reference packet which is a constant is calculated and the count-down processing of an internal timer is performed by using a value for which the value is substrated from the timer value T of the internal timer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a token passing protocol type LA for performing synchronous processing between a plurality of modules.
N.

[0002]

Conventionally, a token passing protocol type L for performing synchronous processing between a plurality of modules has been proposed.
Japanese Patent Application Laid-Open No. 9-275409 is known as AN.
In this configuration, a communication line dedicated to a synchronization signal is provided in addition to a communication line for data transmission in order to perform synchronization control. As another method, even when another device receives and synchronizes the synchronization reference packet transmitted by the reference device, since the data packet and the synchronization reference packet are mixed and flowing, the discrimination process between the synchronization packet and the data packet is performed. Synchronization is lost by the amount of time.

In the case of ISDN, conventionally, only the basic interface (BRI) can make a bus connection, and only two terminals can make a voice call at the same time. Therefore, when trying to use more lines than the basic interface, star wiring was required.
Furthermore, even when connected to the Ethernet, it is not possible to guarantee transmission and reception of call data from a connected device within a certain period of time, so that there has been a problem that the audio delay time is affected by the traffic. In view of the above, an object of the present invention is to simplify a wiring facility and effectively use a conventional facility by enabling a synchronization process with an error within a token circulation time without providing a separate synchronization signal line.

Further, the present invention converts data on a plurality of ISDN lines to a token passing protocol type LAN and transmits / receives the data, so that calls using more than two ISDN lines are connected to a bus instead of a star line. The purpose of the present invention is to simplify the wiring facilities such as cables and make effective use of the conventional facilities by enabling communication with the equipment. A further object of the present invention is to guarantee that the communication quality is always uniform among all devices connected to a plurality of devices in a network for the purpose of communication, regardless of the traffic.

[0005]

SUMMARY OF THE INVENTION To solve the above-mentioned problems, a first aspect of the present invention is a reference device connected to a network, wherein a synchronous reference packet is broadcast by a fixed period T broadcast based on an internal timer. And a means for synchronizing with the reference device by resetting an internal timer based on the reception timing when receiving a synchronization reference packet from the reference device in another device connected to the network. It is characterized by.

That is, one module is used as a reference (master) among a plurality of modules connected on the same LAN cable, and a synchronization reference packet is transmitted to a plurality of apparatuses other than the master at regular intervals by an internal timer of this apparatus. Send to The other connected devices reset their respective internal timers according to the synchronization reference packet, so that the internal timer of the other connected device is synchronized with the internal timer of the reference device. The operation of each device based on the internal timer synchronized at regular intervals enables the synchronized operation of the entire system.

According to a second aspect of the present invention, in the token passing protocol type LAN according to the first aspect, a fixed time t (t <t) after transmitting the synchronization reference packet in the reference device.
T) means for terminating data transmission within T) and means for terminating data transmission / reception within a certain period T based on the measurement time of an internal timer in another device.

That is, even if a device that issues a synchronization reference packet attempts to output a synchronization reference packet at a fixed time period, if another device is communicating at that timing, the token does not turn to the reference device and the synchronization reference packet is not transmitted. In order to avoid that it is not possible to guarantee that the packet can always be transmitted, it is guaranteed that the synchronization reference packet can always be output at a predetermined timing.

According to a third aspect of the present invention, in the token passing protocol type LAN according to the first or second aspect, means for starting measurement of an elapsed reception time at a timing when reception of all packets received by another device is completed. ,
When it is determined that the received packet is the synchronization reference packet, the sum of the reception elapsed time at that time and the reception time of the synchronization reference packet which is a constant is calculated, and the value is calculated from the timer value T of the internal timer. Means for decrementing the count value and setting the count value in the internal timer to start the countdown process of the internal timer.

That is, when a synchronization packet is received,
If the received packet is a synchronous packet, the internal timer of each device can always be reset at an accurate timing without being affected by the processing time for determining whether this is a data packet or a synchronous packet. .

[0011] The invention of claim 4 is the invention of claim 1, 2, or 3.
In the token passing protocol type LAN, when data transmitted and received between devices is audio data,
The audio data is AD-converted at a timing based on an internal timer. In other words, by fixing the amount of data that can be received and transmitted by each device, it is possible to guarantee that constant communication data can be transmitted and received within a certain period of time, and to use the synchronized
By adjusting the input timing in each device, each device can talk with a uniform voice delay time without losing voice data and without being affected by the traffic.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a network configuration when the present invention is applied to an ARCNET of an improved token passing type LAN. In the figure, reference numerals 1 to 3 denote devices, and internal timers 11, 21 and 3 are respectively provided therein.
1 and reception elapsed timers 12, 22, and 32. The internal timers 11, 21, 31 count from 0 to T,
When it is counted up, it is reset and becomes 0 repeatedly.

Here, the device 1 is set as a master, and its internal timer 11 counts up to a count T and is reset. At the same time, the synchronization reference packet 10 is simultaneously transmitted to the devices 2 and 3 by broadcast. This synchronization reference packet 10 is composed of a packet identifier and information on the use status of a channel. When the devices 2 and 3 determine that the received packet is the synchronization reference packet 10, they reset the internal timers 21 and 31 in their own devices. By this operation, the internal timers 11, 21 and 21 of the devices 1, 2 and 3 are set.
31 are synchronized with each other. Accordingly, the devices 1, 2, and 3 operate on the basis of the timers 11, 21, and 31. As a result, the devices 1, 2, and 3 can perform processing operations synchronized with each other.

Next, in order to ensure that the device 1 can always transmit the synchronization reference packet 10 at the cycle T of the internal timer 11, the devices 2 and 3 receive the synchronization reference packet 10 and wait for a certain time t (t <T If it does not elapse, restrict data transmission. FIG. 2 is a time chart showing the relationship between the data transmission and reception timing between these devices 1 to 3. As shown in the figure, after transmitting the synchronization reference packet 10, the device 1 transmits a predetermined amount of data in one token acquisition, and transmits data to the devices 2 and 3 for the determined number of times of token circulation. It shall be sent. Thus, the time required for data transmission is always a fixed time. Further, the data amount and the number of token circulations are set so that the transmission time always ends within time t.

After the time t has elapsed after receiving the synchronization reference packet 10, the devices 2 and 3 also transmit a predetermined amount of data in one token acquisition, and also determine a predetermined number of token circulations. It is assumed that only the device 1 transmits data. Thus, the time required for data transmission is always a fixed time. Further, the data amount and the number of token circulations are set so that the transmission time always ends within the time T-t.

When another device other than the devices 2 and 3 is added to the network, the data amount and the token are set so that the transmission time of all the devices including the newly connected device falls within the period T of the internal timer. Set the number of patrols. By doing so, at the timing when the device 1 sends out the synchronization reference packet 10 in the cycle T, the other devices 2 and 3 have finished communication, and the device 1 The transmission of the synchronization reference packet 10 is not prevented.

Next, the synchronization reference packet receiving device 2,
The processing on the third side will be described. FIG. 3 is a flowchart showing processing on the device 2 or 3 side. The devices 2 and 3 receive the synchronization reference packet 10 (S1) and then determine the synchronization reference packet (S4 YES) for the processing time,
In order to prevent delay in resetting the internal timers 21 and 31 in the own device, the timing (S2YE
In S), the reception elapsed timers 22 and 32 are started (S).
3).

If it is determined that the packet is the synchronization reference packet 10 (S4 YES), the elapsed time measured by the reception elapsed timers 22 and 32 and the time required for the reception processing of the synchronization reference packet 10 from the period T of the internal timer are calculated. This result is set in the internal timers 21 and 31, and the countdown is started from the timer value (S5, S6). When the countdown is completed (S6 YES), the internal timer is reset (S7).

Since the size of the synchronization reference packet 10 is always constant, the processing time required to receive the synchronization reference packet 10 has a constant value. From these facts, the synchronization processing can be performed between the devices 1 to 3 without being affected by the time required for reception and the processing time required for determining the synchronization reference packet 10. When it is determined that the received packet is not the synchronization reference packet 10 (S4 NO), the reception elapse timers 22 and 32 are reset, and the apparatus enters a state of waiting for reception of the next packet.

Further, in the present invention, as described above, the amount of data transmitted and received by each of the devices 1 to 3 within a fixed time is always constant, and when this data is audio data, each of the devices 1 to 3 uses the internal timer 11, When the audio is A / D-converted at the timing based on the internal timers 11, 21 and 31 utilizing the synchronization at the timer period T of the timers 21 and 31, the audio delay in each of the devices 1 to 3 is always the same. . In addition, since a fixed amount of data communication is always performed, voice data is not lost, and as a result, communication without quality deterioration is possible.

[0021]

As described above, according to the present invention, it is possible to perform synchronization processing with an error within the token circulation time without providing a separate synchronization signal line, thereby simplifying wiring facilities and reducing conventional equipment. Effective use becomes possible. In addition, the present invention converts data on a plurality of ISDN lines to a token passing protocol type LAN and transmits / receives the data, so that calls using more than two ISDN lines can be connected to a device connected to a bus instead of star wiring. Calls can be made, wiring facilities such as cables are simplified, and the existing facilities can be effectively used. Further, in the present invention, the communication quality is always uniform among all devices connected to a plurality of devices in a network for the purpose of communication without being affected by the traffic.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a timing chart showing an embodiment of the present invention.

FIG. 3 is a flowchart illustrating an embodiment of the present invention.

[Explanation of symbols]

 1-3 devices 11, 21, 31 internal timer 12, 22, 32 reception elapsed timer 10 synchronization reference packet

Claims (4)

[Claims] 1. A means for transmitting a synchronization reference packet by broadcasting at a constant period T based on an internal timer in a reference device connected to a network, and a reference device in another device connected to the network And a means for resetting an internal timer based on the reception timing of the synchronization reference packet and synchronizing with the reference device, the token passing protocol type LAN. 2. The token passing protocol type LAN according to claim 1, further comprising: means for terminating data transmission within a predetermined time t (t <T) after transmitting the synchronization reference packet in the reference device; Means for terminating transmission / reception of data within a predetermined period T based on a time measured by an internal timer in a device, comprising: a token passing protocol type LAN. 3. The token passing protocol type LAN according to claim 1, wherein a means for starting measurement of a reception elapsed time at a timing when reception of all packets received by another device is completed, and If the packet is determined to be a synchronization reference packet, the sum of the reception elapsed time at that time and the reception time of the synchronization reference packet, which is a constant, is calculated, and the sum is subtracted from the timer value T of the internal timer to calculate the sum. Means for setting a timer to start countdown processing of an internal timer, comprising: a token passing protocol type LAN. 4. The token passing protocol type LAN according to claim 1, wherein when the data transmitted and received between the devices is audio data, the audio data is transmitted at a timing based on an internal timer.
A token passing protocol type LAN characterized by performing D conversion.