JPS59158645A - Method for accessing bus type network - Google Patents

Abstract

PURPOSE:To accommodate voice and data packet terminal devices with excellent matching by classifying transmitting/receiving terminals into two groups and transiting the state from the 1st group to the 2nd group when a transmission request is produced at a voice packet terminal. CONSTITUTION:A token is circulated to transmission/receiving terminals 302(1)- 302(L) and 301(1)-303(M) constituting a bus type network at first in the 1st group of the entire ring structure 301 to transmit/receive a packet. When a transmission request is produced in a voice packet terminal in this group, the terminal sets a call, causing the state to be transited to the 2nd group of the branch structure 300 and to flow the token in the direction of the arrow 304. When the voice packet terminal completing the call setting earliest in the voice packet terminals sets a timewise origin when the token is obtained and offers the service to the 2nd group while receiving and supplying the token sequentially after the setting of origin. When the service is finished, the terminal returns to the 1st group until a prescribed time is elapsed and hands over the token sequentially. When the prescribed time is elapsed, the terminal in possession of the token supplies the token to the head voice packet terminal.

Description

Detailed Description of the Invention The present invention provides a bus-type network in which a plurality of transmitting and receiving terminals are connected to a single transmission path in a bus-like manner, and transmitting rights are sequentially received and transferred, thereby enabling backt communication between each transmitting and receiving terminal. The present invention relates to a network access method and a transmitting/receiving device thereof.

Conventionally, a well-known method for accessing a bus-type network involves firstly detecting the gear 11a on the base bus where a communication request has occurred at the terminal, and if no carrier is present on the bus, the terminal CNM Volume 19. sends a signal to the bus, and if another terminal sends a signal at the same time and causes a collision, it stops sending the signal, and then sends the signal again after a certain period of time. Number 7, Schlei, 1976 (CAC~1 vol, 19.
No, 7. July, 1976) K 1'W f
il R,M Metcalfe ('R,M.

Ethernet: Distributed Packet Switching by Metcalfc, etc.
local computer network'('Ethe
-rnet: Distributed Packe
t Switching for Local Comp
uter Network'). This method is based on CSMA/CD (Ca=rrj
er 5ense Mtlltiple Access
This is a packet access method well known as the /CoIlIsionDetection) method.

Second, the receiver sequentially passes transmission rights (hereinafter referred to as tokens) to the transmitting and receiving terminals on the bus, so that only one transmitting and receiving terminal has this token at a time, and the terminal that obtained the token can The method of obtaining the right to use the
802 Comm1ttee.

LAN 5standard Draft C, May
1982), Chapter 4. This method is a well-known packet access method such as a token bus.

These bus networks were designed primarily to accommodate terminals that handle data, such as computer computers, and to accommodate real-time terminals that handle audio, video, etc., delays within the network are caused by terminal activity. This is difficult because it can vary greatly. However, these days, due to the spread of office automation, different types of traffic (e.g., voice, work image, data/traffic with different communication/call quality and speed requirements) are being transferred within the same network. There is an increasing demand for accommodating these devices due to their economic efficiency and scalability. Under these circumstances, in the C8MA/CD method described above, an attempt has been made to give high priority to packets that require real-time performance such as audio, and to keep network delays to a minimum.
This is a ``Random Access Wired Packet Communication System with Priority'' by Yasuda and Ishizuka at the 1978 National Conference 3A-1 of the Information Processing Society of Japan - Priority Ethernet.
It is described in t. However, even with this method, when the activity of signals that require real-time performance such as voice increases, collisions between high-priority real-time voice and other packets frequently occur, resulting in an increase in network delay. Communication of real-time signals such as quality voice becomes impossible. Further, in the token bus, an effective method for accommodating heterogeneous traffic will be ignored, and packets such as data, which can be delayed to some extent, are synonymous with data packets.

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional methods,
The object of the present invention is to provide a bus-type network access method capable of accommodating voice packet terminals and data packet terminals with consistency and efficiency and easy completely distributed control.

According to the present invention, in a bus-type network in which a plurality of transmitting and receiving terminals are connected to a single transmission path in a bus-like manner and packet communication is performed between each transmitting and receiving terminal by sequentially receiving and passing tokens, the transmitting and receiving terminal is connected to the first transmitting and receiving terminal. Classified into two groups: ゜Hong 2,
Normally, all sending/receiving terminals belong to the first group, but when a request for sending/receiving occurs at a voice packet terminal in the first group of terminals, this voice packet terminal performs call setup and enters the second group. When the transmission/reception (transmission/reception) is completed, the terminal returns to the first group and sets up the call first among the second group.When the first voice packet terminal obtains the token, it sets the time origin without any delay. After that, the service for the second group is performed by passing the next token, and when the service is finished, the service for the first group is performed by passing the token sequentially until a predetermined period of time has elapsed from the time origin. After a certain period of time has elapsed, the terminal that has the token at that point receives and passes the token to the first audio packet terminal. , Network access of a bus-type network that also has the function of measuring the time that the second group receives service at that time when the state transitions to the second group, and determining whether or not to move to state 4 based on the measured value. method is obtained.

It shows the basic physical configuration of the network.

100 is a transmission path, 101(1,) to 101(N) are transmitting/receiving terminals, and 102(1) to 102(N) are voice terminals such as telephones and various computer data terminals. Each transmitting/receiving terminal is passively connected to a transmission path 100. That is, for example, the signal sent from even the transmitting/receiving terminal 101(2) is transmitted bidirectionally as indicated by the dotted arrow 103, and each transmitting/receiving terminal can detect the signal. FIG. 2 shows the structure of a conventional system focusing on receiving and passing tokens. In other words, it can be thought of as a token flow chart showing in what order tokens are passed between sending and receiving terminals. In Figure 2, there are 4♂, 200(1) to 200 (the dipper indicates the transmitting/receiving terminal, and the token is 1 in the direction of the arrow shown at 201).
11a Next reception is passed, and when each sending/receiving terminal receives a token, if there is sending data, it sends the data, finishes sending and passes the token to the next sending/receiving terminal, and if there is no sending data, it is a dead end. passes the token to the next sending/receiving terminal. Each transmitting and receiving terminal has an address, and the order in which the tokens are transferred is determined in advance, i.e.,
This can be done if each sending/receiving terminal has information about which address terminals to receive tokens from and which address terminals to send them to. Since the token passes through the same sending/receiving terminal many times, it logically forms a ring structure as shown in FIG.

However, with such a logical structure, when focusing on a particular transmitting/receiving terminal, the cycle at which the tokens come around changes depending on the thread activity.

(If the activity of the system is small, the period will be short, but if the activity of the thread is large, the period will be long.) Therefore,
Accommodating terminals that must send signals at regular intervals, such as voice communication, ensures real-time performance.
This is difficult in terms of scalability.

The present invention was devised to eliminate such drawbacks of the conventional method. FIG. 3 shows the logical network structure of the present invention. This logical structure is obtained by dividing the conventional logical structure shown in Fig. 2 into two, and 30 in Fig. 3.
The ring structure indicated by 1 is a conventional logical structure, and a branch structure indicated by 300 is added thereto. In the figure, 302(1) to 302(L) indicate transmitting/receiving terminals belonging to the branch structure, and 303(1) to 303N indicate transmitting/receiving terminals belonging to the ring structure. Furthermore, tokens flow in the direction of the arrow 304 in the transmitting/receiving terminals belonging to the branch structure, and tokens flow in the direction of the arrow 305 in the transmitting/receiving terminals belonging to the ring structure. In the initial state of the network, all branch structures have the state M. This means that the audience structure of the network, that is, the order in which tokens are received changes, so the network logical structure unique to each sending and receiving terminal changes. State C (hereinafter abbreviated as NLS) must be changed.

The NLS differs from an acoustic packet terminal that may migrate to a branch structure and a data bucket terminal that operates only within a ring structure. The voice packet terminal has an NLS Sv shown below, and the data packet terminal has an NLS SD shown below.

Sv −(BH, BT, R++, RT, P, S
) SD - (BH, BT, P, S) Here, the address of the first transmitting and receiving terminal of BH Nibranch Hirozo (third
302(1) in the figure) Address of the last transmitting/receiving terminal in the BT + branch structure (302(L) in Figure 3) RH: +1 Address of the first transmitting/receiving terminal of Sakakizo (in Figure 3) RT: Address of the last transmitting/receiving terminal in the IJ ring structure (1 to 303 in Figure 3)) RT: Address of the last transmitting/receiving terminal in the IJ ring structure (1 to 303 in Figure 3) 303 (h4)) P; Considering the terminal whose address (for example, 303f3 in Fig. 3) of the transmitting/receiving terminal that has the relevant NLS receives the token, 303 (terminal address of 21) S: Address of the transmitting/receiving terminal to which the transmitting/receiving terminal that has the NLS sends the token (for example, 303 (3
(Consider terminal 1 and terminal address 303 (4)) For both SV and SD, the order of the variables in parentheses may be in any order, and there is no problem with having a state that includes this information. Also, BHBT, RH,R
T has meaning only in the case of a network logic structure where transmitting and receiving terminals exist in a branch structure. Furthermore, the voice packet terminal with the address of BH has P blank (
(hereinafter referred to as ``me''). A transmitting/receiving terminal having an RH address can have two types of P such as a ring structure and a branch structure X5≧, but it is sufficient to have only the address of the terminal currently being created as information. Each transmitting/receiving terminal existing in the ring structure that has received the call setup frame sets the address of the voice packet terminal that will perform the call setup as A, the address of the transmitting/receiving terminal immediately before this voice packet terminal as Ap, and the address of the transmitting/receiving terminal that is one after this voice packet terminal. Let A and s be the sending/receiving terminal addresses of , then, for example, the following changes are made.

・BT:→A ・R+(:→A3 IRIT:→Ap) Each transmitting/receiving terminal existing in the branch structure changes its NLS (if any) as follows, as an example.

BH: No change BT: →A RH: →As RT; →Ap P: No change As described above, by changing the NLS, the network operates under a new network logical structure.

An example of a change in this network logical structure will be shown using FIG. Now, for example, when ten transmitting/receiving terminals exist in a network and the network has a logical structure as shown in FIG. 5(a), it is assumed that the voice packet terminal at address 5 sets up a call. The numbers shown in the figure indicate the addresses of the sending and receiving terminals, and the tokens are passed in the direction of the arrow. When the call setup is complete, the network logical structure changes to the state shown in Figure 5 (b) according to the state change rules described earlier.
). For example, the internal state of the terminal at address 8 is (assuming that the terminal at address 8 is a voice packet terminal)
, (OLD) Sv - (1311, BT, m4 RT, P
, S) −(1,2,3,10,7,9)↓ (NEW) Sv −(13)(, BT, RH, RT, P,
5) - changed to (1, 5, 6, 4, 7, 9,).

Similarly, the internal state of the terminal at address 6 is ~ ↓ (NEW) Sv −(J3Fr, BT, R1(, RT,,'
R5)-(1,5,6,4,4,7). Next, when the voice packet terminal existing in the branch structure finishes transmitting and receiving, it has the same structure as the frame shown in FIG. Send the frame when you get the token and return to the ring structure. At this time, the voice packet terminal that released the call returns to the last position in the ring structure, and the previous sending/receiving terminal address is set to the previous RT.
The next transmitting/receiving terminal address becomes the previous RH. Each transmitting/receiving terminal that has received the call release frame sets the address of the voice packet terminal that performs the call release to A as before, and sets the address of the transmitting/receiving terminal immediately before this voice packet terminal as A.
p. Assuming that the address of the transmitting/receiving terminal after this voice packet terminal is As, the address is changed as follows as an example.

In the case of I-A\BH, BT ・B14. BT, RH: No change ・RT:→A +1. In the case of A-BH Italian BH:→As ・BT,'RH: →No change ・RT:→A ■, A-BTO gift ・Brt: No change ・BT:→Ap ・k%H: No change ・1(IT:→A An example of changes in the network structure will be shown using FIG. 5 again.

Suppose that the voice call terminal at address 2 cancels the call from the state shown in FIG. 5(b). When the call release is completed, the network logical structure changes as shown in FIG. 5(C) according to the previous state change rule. For example, the internal state of the terminal at address 8 is ↓ (NEW) Sv JBl(,BT,,RH,RQ",P,
8) - (1, 5, 6, 2, 7, 9). Similarly, the internal state of the terminal at address 6 is ↓ (NEw) Sv - (Bl-[, BT, RJ-L'R
T, P, 5) - (1, 5, 6, 2, 2, 7).

Next, a method of signal access to the transmission path will be explained using the drawings. When the transmitting/receiving terminal having the address of BH, that is, the transmitting/receiving terminal at the head position of the branch structure (terminal 302 (]) in Figure 3) obtains the token, it sends 11 set frames to all transmitting/receiving terminals. do. The reset frame has the same structure as the frame shown in FIG. 4, except that the access control field 403 contains a code indicating +1 setoff L/-A, and there is no information field 406 to be sent. When each transmitting/receiving terminal receives a reset frame, it sets its built-in timer to 11, and although there is a difference due to propagation delay in the transmission path, the same time origin T is reached.

will have the following. The following explanation will be given using the network structure shown in FIG. After sending out the reset frame, when the terminal in 302(1) changes the call setup, it sends a signal equal to the number of information units to inform all terminals, and updates its own NL.
By referring to S, the terminal address to which the next pressure token should be sent can be found, so the receiver passes the token to the terminal at 302(2). When the terminal at 302 (2> receives and receives the token, it sends its own signal, and the terminal at 302 (passes the token to the terminal at 3'l. This operation is repeated in sequence 302σ)) receives the token at 303 (1). ), the service for the sending/receiving terminal of branch j Masazo ends, and after that, the service for the terminals 303(], ) to 303(~) in the ring structure is still done by passing the token. Services for terminals belonging to this ring structure are provided until a certain period of time '1' has elapsed from the time origin T (the token passes around the ring structure many times).

That is, a sending/receiving terminal belonging to the 11 ring structure may receive multiple tokens and receive multiple services. ), when a certain period of time T' has elapsed, the transmitting/receiving terminal that has the token at that time immediately returns to 306 in Figure 3.
The receiver passes the token to the terminal 302(1) via the route .

302+1. ) receives the token, its built-in timer sends out a reset frame when a certain period of time T has elapsed since TO, and the same process as before is repeated. Here, the relationship between T and T/ must satisfy T≧T'+Δ'11. △T is the propagation delay length of the transmission path between the two farthest terminals belonging to the network.
ρ is the time that shows the times. Branch (
If there is no fourth structure, there is no time origin and the network operates in the form of a normal token bus. FIG. 6 shows an example of the flow of packets on the transmission path. Note that the token frame is omitted in FIG. 6. In the figure, the horizontal axis indicates the time axis, 600(1) to 600(2) indicate reset frames, 601(1) to 601(6) indicate packets from transmitting/receiving terminals belonging to the branch structure, and 602(1)
~602(4) indicates packets from transmitting/receiving terminals belonging to the ring structure. In the figure, T indicates the sending time interval of the reset frame, and T1 indicates the time interval for transmitting the reset frame.
The service time, T2, indicates the service time for the ring structure. In this example, 601(1) and 601(4),
601. (2) and 601(5), 501(3) and 60
1 (6) are packets from the same transmitting and receiving terminal, and it can be seen that one guaranteed packet transmission every time T is guaranteed.

Using the method described above, each transmitting/receiving terminal can access the transmission path, and the η characteristics shown below can be obtained. First, transmitting and receiving terminals in a branch structure in a logical network can reliably transmit synchronous packets, that is, transfer a fixed amount of data at fixed intervals, by setting a common time origin using a reset frame2. It is possible to do so. In other words, it is possible to accommodate terminals that require strict real-time performance, which was conventionally difficult to accommodate because there is a delay and the amount of continuation can vary greatly depending on network activity. Second, the common time origin is relative as there is no need to provide a special terminal to define the time origin (i.e. branch 414 generator).
If it does not exist, the time origin does exist, and if the terminal that has set the time IY5 origin cancels the call, the next transmission/reception terminal will be responsible for setting the time origin. ) No.b that enables base software access with completely fractional control. As a result, it is possible to obtain the effect of improving one-note retention.

Third, data packet terminals belonging to the ring structure operate in the same way as in the conventional method (burst data transfer is of course possible), but are subject to transmission quality deterioration (increase in delay time) that adapts to the activity of the voice packet terminal. Therefore, a network 1N4 including heterogeneous traffic can be constructed very efficiently.

Here, when the activity of the packet terminal increases, the service time for the branch structure becomes longer, and the service time for the data terminal belonging to the ring structure becomes shorter. Therefore, in order to accommodate voice packet terminals and data packet terminals with good consistency, it is possible to provide an activity control function and control voice packet calls. For example, it is conceivable to control voice calls according to the following rules. Suppose now that a call occurs at a certain voice packet terminal. Assuming that the service time for the branch structure at this point is TB and the service time for the ring structure is TR, the relational expression TB+TR-Tfl holds true. T takes a constant value at the reset frame transmission period. At the end of this voice Xi, by observing its own NLS, the TnO value at that time can be determined. So this T
If B is less than a certain time Tc, the call is set up, and if it is greater than Tc, the call is rejected, thereby making it possible to secure the service time for the data packet terminal.

Next, the operation will be explained with reference to the block diagram of FIG. 7 showing an embodiment of a transmitting/receiving device implementing the bus type network access method of the present invention.

700 indicates a transmission line, and the signal from the transmission line is transmitted through a signal line 75.
0 and is input to transceiver 701.

The signal is amplified and shaped by the transceiver 701 and sent to the signal line 7.
51. The signal on the signal line 751 is input to a synchronization detection circuit 702, and a clock signal is output on the signal line 752. The signal on the signal line 751 is still input to the register 703, synchronized with the clock signal on the signal line 752, and output to the signal line 753. A packet disassembly circuit 704 disassembles the packetized signal and outputs the header field to the signal line 754 and the information field to the signal line 755 from among the packet signals for one frame from the signal line 753. The header fields on signal lines 754:6- are input to the header decoding circuit at 706. When the header decoding circuit 706 detects the token addressed to this transmitting/receiving terminal, it notifies the audio terminal or various data terminals (hereinafter referred to as connected terminals) connected via the signal line 759 that the token has been obtained. . If there is transmission data, the connected terminal notifies the header decoding circuit 706 of the presence of transmission data via the signal line 758. In addition, in the header decoding circuit of 706,
If information addressed to this transmitting/receiving terminal exists, the signal line 760
to inform the connected terminal via the information register 707.
The information field in the received packet is sent to the connected terminal via signal fffA764. Furthermore, when the header decoding circuit 706 detects the I/set frame from the header information on the signal line 754, it outputs a reset pulse to the signal line 756 and resets the timer 705. timer 7
In 05, after a certain period of time has elapsed from the 11 set pulse manually, the time g g signal is sent to the signal line 757.
06 header decoding circuit. When the header decoding circuit 706 detects a call setup frame or a call release frame from the header information on the signal line 754, it decodes the signal line 76.
Output NLS change data to 2, and output NLS to B@ line 761.
Outputs the address change instruction for which part of the file is to be changed. 708 is a memory control circuit, 7o9 is a memory for storing NLS, and the memory control circuit 708 is connected to the signal line 76.
1 is input, and the memory address of the changed location and a memory write signal are output to the signal line 765.

The memory 709 stores the memory address and memory write signal NLS data input from the signal line 765. The memory contents of 709 are its own address, a code for the access control field, and the above-mentioned internal information (3NLS). The signal line 763 outputs its own address, access control code, and the address of the terminal to which the token should be passed. Also, when setting up or canceling a call, the terminal one before the own terminal and one terminal next to the own terminal are output. Noah)-res is also output and input to the packet assemble I) circuit 71o. Packet assembly circuit 7
10 further receives information from the connected terminal and the address of the other party's transmitting/receiving terminal with which communication is desired, and outputs it to the signal line 767 assembled into a packet according to the frame format shown in FIG. Ru. The signal on the signal line 767 is input to the transceiver 701, amplified, and then output to the transmission line 700 via the signal line 750.

In FIG. 7, the backt signal control can also be performed by software of the processor, and it goes without saying that the present invention also includes implementation of this method by software control.

FIG. 8 shows a block diagram of another embodiment of the present invention. This system is basically the same as the implementation shown in FIG. 7, but an activity control circuit is added to allow voice packets and data packets to be integrated into the network with good consistency. The operation will be explained below. 800 indicates a transmission path;
The signal from the transmission path passes through the signal line 850 to the transceiver.
801. No. 11 is amplified and shaped by the transceiver 801 and output to the signal line 851. signal line 85
The signal 1 is inputted to the synchronization detection circuit 802, and the signal line 8
A clock signal is output to 52. Signal line 851 (m
The signal is also input to the register 803, synchronized with the clock signal from the signal line 852, and output to the signal line 853. 8(+4 is a packet disassembly circuit that disassembles the packetized signal, (=(=, line 853
The header field of the packet signal for one frame from the signal line 854 is the information field.
Output to 5. The header fields of the i'fT line 854 dh are input manually to the header decoding circuit of 806.

The header decoding circuit of 806 detects the ldl 1-kun addressed to this transmitting/receiving terminal, and the 806
11 Activity 1δ1] Notify the Gokai 1 Tower.

Furthermore, from the signal line 858, there is an activity i (t
Sent to control circuit. The activity control circuit 811 updates the service time for the branch and structure every time a call is set up or canceled, and always has the latest service time information. When a token is passed to this transmitting/receiving terminal and an If setting request is received from a continuous terminal via 86 information lines, whether the service time for the branch structure at that point satisfies the conditions for call setting is possible. Make a rejection decision.

The result of this determination is notified to the connected terminal via the signal line 868, and if the call setup is not possible, the call setup request is rejected.

In the header decoding circuit 806, if information addressed to the transmitting/receiving terminal exists, it is notified to the connected terminal via the signal line 860, and the information is sent via the information register 807 to the signal line 864.
The information field in the received packet is sent to the connected terminal.

Furthermore, when the hetsuta decoding circuit 806 detects a reset frame from the header information on the signal line 854, the signal line 854
6, a reset pulse is output and the timer 805 is reset. The timer 805 sends a timeout signal to the signal line 857 after a certain period of time has elapsed since the reset pulse was manually input, and the timeout signal is input to the header decoding circuit 806 . 80
When the header decoding circuit 6 detects a call setup frame or a call release frame from the header information on the signal line 854, it outputs NLS change data to the signal line 862, and outputs the NLS change data to the signal line 862.
1, an address change command indicating which part of the NLS is to be changed is output. 808 is a memory control circuit, 801t, NL
The memory control circuit 808 inputs an address change command on the signal line 861, and
5, the memory address of the changed location and the memory write signal are output. The memory 809 uses the memory address and memory write signal input from the signal line 865 to read the modified NLS data from the signal line 862 and the signal line 855.

The memory contents of 809 are its own address, pins for various access control fields, and the internal NLS described above.The signal line 863 contains its own address, access control code, and the name of the terminal to which the token should be passed. Addresses are output, and when setting and canceling calls, the addresses of the terminal before and after the own terminal are also output.
input to the circuit.

The packet assembly circuit 810 further receives information from the connected terminal and the address of the other party's transmitting/receiving terminal with which communication is desired, is assembled into a packet according to the frame format shown in FIG. 4, and is output to line 1d 867. be done. The signal on signal line 867 is transmitted to transceiver 801.
80 through the signal line 850 after being amplified.
Output to the 0 transmission path.

In FIG. 8, packet signal control and activity control can also be performed by software of the processor, and it goes without saying that the present invention also includes implementation of this method by software control.

As shown above, the access method of the present invention makes it possible to accommodate real-time signals such as audio into a bus network without delay, and is also possible with easy complete distributed control using the internal state of the network. , a system can be created that is highly suitable for local area networks that accommodate heterogeneous traffic effectively and consistently.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic physical configuration of the token bus network, FIG. 2 is a diagram showing the logical network r#M of the conventional token bus, and FIG. It is a diagram showing the network structure of
FIG. 4 is a diagram showing an example of a call setup frame, FIGS. 5(a), (b), and (C) are diagrams showing examples of changes in the network logical structure of the present invention, and FIG. FIG. 7 is a block diagram showing an embodiment of the method of the present invention, and FIG. 8 is a block diagram of an embodiment of the method of the present invention. It is a diagram. In the figure, 100.700.800...old transmission line, 101(1) to 101(N)...transmitting/receiving terminal, 102(1) to 102(N)... ...Face connection terminal, 701.801. ...... Transceiver-1702, 802 ...... Synchronization detection circuit, 703.803... Kawamoto register, 704, 8
04...Packet disassembly circuit, 7
05゜805・・・・・・・Timer, 706.8
06... River... Header decoding circuit 707, 807...
...Information register, 708.808...Memory control I! :11th road, 709.809...=-me%
I+, 7 ], 0.810...- track back assembly circuit, 811... activity control circuit. Vines 1 Mouth IO2 (1) 102 (2) 102 (3
) 102(N) etc. 2 Figure 3θ6 Figure 4

Claims (2)

[Claims] (1) In a network access method for a bus-type network in which a plurality of transmitting and receiving terminals are connected in a bus-like manner to one transmission line and packet communication is performed between each transmitting and receiving terminal by sequentially receiving and passing transmission rights, the transmitting and receiving terminals are It is classified into a first terminal set and a second terminal set, and each transmitting/receiving terminal usually belongs to the first terminal set, and transmits and receives data at the real-time transmitting/receiving terminal that handles real-time signals among the first terminal set. When a request occurs, the real-time transmitting/receiving terminal obtains the right to transmit, transmits a call setup frame, transitions to the second terminal set, and the real-time transmitting/receiving terminal of the second terminal set completes transmission/reception. makes a state transition to the first terminal set by sending a call release frame,
When the leading real-time transmitting/receiving terminal that set up the call earliest among the second terminal set obtains the transmission right, it first transmits a time origin setting frame, and then services for the second terminal set are sequentially performed. When the service ends, the service for the first terminal set is changed from the time origin to
This is carried out until a predetermined period of time has elapsed, and when the period of time has elapsed, the Hello terminal has the transmission right at that point (the Hello terminal is characterized by receiving and passing the transmission right to the first real-time transmitting/receiving terminal). A bus-type network access method. (2) In a network access method for a bus-type network in which a plurality of transmitting and receiving terminals are connected to a single transmission line in a bus-like manner and packet communication is performed between each transmitting and receiving terminal by passing the transmission right from one transmission line to another, Terminals are classified into a first terminal set and a second terminal set, and normally each transmitting/receiving terminal belongs to the first terminal set and is connected to the real-time terminal that handles real-time signals in the Ml terminal set. When a transmission request occurs, the real-time terminal measures the entire time during which the second set of terminals receives the service, and if the time during which the second set of terminals receives the service is less than or equal to a predetermined time, the real-time terminal obtains the right to transmit. By sending a call setup frame, the real-time terminal transitions to the second terminal set, otherwise rejects the transmission request, and sends a call release frame after the real-time terminal has finished transmitting and receiving at the second terminal set. Then, the state transitions to the first terminal set, and when the first real-time terminal in the second terminal set that sets up the call earliest obtains the transmission right, it sends out a time origin setting frame, and its apprentice Services for the second set of terminals are sequentially performed, and when the service is completed, services for the first set of terminals are performed from the time origin until a predetermined period of time has elapsed, and the specified period of time has elapsed. Then, the bus-type network access method is such that the terminal that has the transmission right at that time receives and passes the VC transmission right to the leading real-time terminal.