JPS60201758A - Data transmission system - Google Patents

Abstract

PURPOSE:To decide the packet transmission direction from own node just with comparison of the own node address by setting addresses so that they are successively increased from the end at one side through the other end of a transmitter. CONSTITUTION:Nodes 101-105 are connected in series via a communication medium 100, and terminals or servers (hosts) are connected to these nodes. Each of these nodes has a node address setting part and sets a network address. These node addresses are increased or decreased successively from the end at one side to the other end of a transmitter. As a result, the packet transmission direction can be decided just by comparing a transmission request address given from the host with the own node address and without storing nor changing the network constitution with nodes.

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a data transmission method for a network system in which a plurality of transmission devices are connected in series via a communication medium. [Prior Art] Conventionally, there have been the following three types of network topology for transmitting data between a plurality of data transmission devices (hereinafter referred to as nodes). (1) A star topology connects all users to a central node capable of managing all communications. Both the advantages and disadvantages of this topology arise from this centralization. Although communication and source management are performed efficiently under the control of a central node, the limitations and reliability of the central node determine the performance characteristics of the entire network. In addition, connecting a central node to other nodes requires longer cables, which often results in higher costs.Also, since all connections between neighboring nodes go through the central node, the number of relay stages and relay call volume are reduced. It ends up being too many. (2) The ring fist topology is simpler than the star configuration, so the cost of connecting nodes and other network elements is cheaper, and it is also a way to eliminate the bottleneck caused by the central node's capacity. However, this time, the reliability of the entire network depends on each individual! t
It becomes dependent on the continuation node. Messages only circulate in the -direction, so unless each node understands the network configuration and eliminates access to nodes that do not form the network, messages will circulate within the network, and the data will continue to flow. If the data is sent, a collision with the circulating data will occur, which requires complicated control. (3) The path topology is almost the same as the ring in terms of topological simplicity, and employs passive connections to prevent loss of reliability. However, many nodes are connected to a normal-tree communication medium, and when there is high-traffic data transmission between specific nodes, communication of other nodes is severely restricted, making it difficult to transmit high-density data. I could not do it. [Purpose] The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide data that can be exchanged in packets with high efficiency through easy transmission control and a simple configuration of each node constituting a network. This is where we propose a transmission method. [Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a serial packet switching network system, which is a network system according to the present invention, in which 100 is a communication medium, and 101-105 are transmission devices that perform transmission control and are connected in series via the communication medium 100. (hereinafter referred to as a node), 110 to 113 indicate each terminal or server (hereinafter referred to as a host) connected to the node 101,
In this embodiment, up to four hosts can be connected to each node. The communication medium 100 between each node is bidirectional, and packet communication is performed independently between the nodes. The packet frame configuration for this packet communication is
It is shown in Figure and tR3 diagram. FIG. 2 is a diagram showing the packet frame structure used in this system, where 201 is a start flag for starting an l frame, 202 is a destination address field of the frame, 203 is a source address field, and 204 is a transmission described later. This is a command that indicates control of a node's entry into the network, response as to whether received data is correct or incorrect, data communication control such as broadcast communication control, node status, etc. 205 is a data length designation section indicating the length of the transmission information field. 206 is a transmission information field having a maximum length of 256 bytes. -207 is a CRC check code of the frame and is for error control. Note that 208 is an end flag. The above-mentioned destination address section 202 and source address section 20
3 is shown in detail in FIG. 2(B). The address part consists of a node address 211 indicating the address of the node, a group address 212 indicating the address of the group to which the host connected to the node belongs, and an intra-group address 213 indicating the address within the group to which the host belongs. Table 1 shows examples of this group name and group address. Here, an example is shown in which the groups are divided into hosts according to the R5-232G standard, hosts according to the GP-IB standard, printer servers, and file servers. In addition to the data packet frames mentioned in Table 1, there are polling control frames shown in FIG. 2(A) and selecting control frames shown in FIG. 2(B) as control frames between nodes and hosts. , the polling control frame for polling consists of "EOT" 221, polling code "POL" 222 and "ENQ" 223, and the selecting control frame consists of "EOT" 221 and selecting code "SEL" 224, E N
223. The host uses this control frame to perform polling and selection for the nodes, and sends and receives data. Next, the configuration of the nodes in this system will be explained with reference to the block diagram in Figure 4. Explanation: The node 300 is the node l 01 and Vl 05 in FIG.
The communication media 100a and 100b are connected to a line connection control unit 301,
controls to connect both communication media when the node 300 is stopped, and to disconnect both communication media when the node 300 is operating. For example, this line connection control 1
Reference numeral 301 is a normally closed type relay, which has a structure that closes when the power of the node 300 is turned on, so that both communication media 100a and 100b are connected when the power of the node is turned off. Control can be performed without any influence. A transmission circuit A304 is connected to the communication medium 100a via a transceiver A302, a transmission circuit B505 is connected to the communication medium toob via a transceiver B503,
The received packet data on the communication medium is sent to the control unit, and the transmitted packet data is sent onto the control communication medium. 306 is a node address setting section;
A network address of 00 is set. This node address is set so that the value becomes larger (or smaller) in order from the node connected to one end of the system to the node connected to the other end. In the example of FIG. 1, node lO1 has node address (#O
1), node 102 (SOS), node 103 (#
lO), no F104 (#18), node 105 (
#20) is the address setting. By setting the mate address so that it increases by the 14th order in the -Y direction in this way, the node does not have to update the memory of the network configuration, and can automatically perform the process by simply comparing the send request address from the host and its own node address. The direction in which the packet is sent from the node can be determined, and whether the transfer request packet sent to the node is destined for the node in the sending direction or not can be immediately determined by comparing it with the node's address. A control unit 310 controls the transmission circuit A 304 or the transmission circuit B 505 to perform packet exchange on the communication medium 100a or 1oob. - The force control unit 310 has a configuration for data communication with each connected host, and depending on the configuration of the transmission interface unit, some parts can be used by R3232C standard hosts and others can be used by GP-IB standard hosts. It is divided into possible parts. A maximum of four lines of hosts can be connected to the control unit 310, and a socket address setting unit (C(
321), D (331), E (341), F (35
1) l and transmission circuit (C(332), D C332
), E (342), F (352)) and transmission interfaces (C (323), D) between each transmission circuit and the host.
(333). E (343), F (353)). Next, details of each transmission circuit section will be explained with reference to the block diagram of FIG. 5. Reference numeral 502 corresponds to a transceiver (corresponding to 302 and 303 in Fig. 54) in the case of transmission circuits A304 and B505, and a transmission interface in the case of transmission circuits C322 and B332, B342 and F352 (corresponds to 323 in Fig. 4).
．． 333, 343, and 353). Prior to frame reception, the carrier signal sent to the communication medium 2 is detected by the carrier detection unit 523 via the interface unit 502, and then detected by the reception circuit 52.
0 is set as a ready state. Also, the interface section 502
The received data and the like are manually input to the receiving circuit 520, and the input frame data is transferred to the receiving 4+j buffer 521. At that time, only the address part in the received frame is stored in the address register 522, and the address data set in this address register 522 is passed to the comparison unit 524 by the address setting unit 501 of the own node (3 in FIG.
06 or 321.3.31, 341.351] and the comparison result is sent to the control unit 310.
is output to. The frame to be transmitted is sent from the control unit 310 to the transmission buffer 5.
11, and then sent from the transmitting circuit 510 to the communication medium via the interface section 502. The communication control of this system will be explained below. First, host communication control will be explained with reference to a flowchart showing host communication control in FIG. 6. In this system, all data communication between the host and nodes is performed by polling or selecting from the host. In other words, the host side takes the initiative in communication. When the post determines that there is data to be sent from its own host at step lσ0, the process proceeds to step 102, where it generates a transmission frame as shown in FIG. In this case, priority is given to the setting value of the address setting section 501 of the node section as the source address 203, and the setting value of the address setting section 501 of the communication medium 100 is given priority.
01 is sent as the source address 203. In data communication between a host and a node, unlike packet communication between a node and a node F, which will be described later, all data that needs to be sent and received is transmitted at once. Subsequently, in step 104, the selecting frame shown in FIG. 3(B) is sent to the 7-card. Then, in steps 106 and 108, it is checked whether there is any received data (response) before timeout. If there is no received data, the process proceeds to step 122, and an EO is sent to the node.
Send out T''' and return to step 100 to select one inner claw. In step 106, if there is 16 data received, check whether the received data is ACK''' or ACK. If not, return to step 100 to indicate that the node is not ready to receive data. Wait for the preparation to be completed.” If the “A CK”°° is received, proceed to step 112,
A transmit data frame is sent to the node and then timeouts are monitored in steps 114 and 116. In the case of timeout, the process proceeds to step 122 described above, and if data has been received, the process proceeds to step 118 to check whether or not the received data is "NAK".
”, the transmitted frame is not received by the mate for some reason, so the transmitted frame is invalidated, and the process returns to step 112 to redo communication control. If not NAK"', step 12
0 and checks whether it is 'ACK', and if it is 'ACK', the transmitted frame has been correctly captured in the notebook, so it returns to step lOO and finishes the data reception process, and returns to ''A'.
If not “CK”, proceed to step 122 and “E”.
OT'' and returns to step 100. If there is no data sent from the host in step 100, the process proceeds to step 130, and the note shown in FIG. 3(A) is sent.
Send out the polling frame shown in step 132,
In step 134, wait for a response from the node until timeout. If there is no response, the process returns from step 134 to step 100. If there is a response, the process proceeds to step 136.
Check to see if it is a "EOT" response or a device. If it is an "EOT" response, return to step 100 to minimize the fact that there is no data sent from the node to the host. If "E O'r" is not received, the node sends the data file. It is assumed that the frame has been sent, and the sent data frame is received in step 138.Then, in step 140, the check code (BCC check code) 207 of the data frame is received.
Check to see if there is a reception error in the received frame. If there is a reception error, the process proceeds to step 142, where it sends ``N A K'' to the node, invalidates the received frame at step 144, and returns to step 132, where it waits for the data frame to be retransmitted. . If the frame is correctly received in step 140, the process proceeds to step 146 and sends an "ACK" to the node, followed by steps 148 and 150 where it is monitored until timeout whether or not "EOT" is received. Node V″A
If the ``CK'' code is sent incorrectly and the data communication is normal, the node sends the ``E O'' code, and the process returns from step 148 to step 100.
Prepare for the next data communication. If the "EOT"° code is sent and a timeout occurs, the data communication will not be able to proceed normally for some reason, and the process will proceed from step 150 to step 152, invalidating the received data and returning to step 100. .In explanation 1 of ``2'', when sending data to another host connected to the same white node, the destination address 2
By specifying the own node address as 02, data can be sent from a host to another host via the node. Next, the communication control on the node side of node-host communication is
This will be explained with reference to the flowchart shown in the figure. The notebook starts operating by activation (polling selection) from the host. First, in step 200, the carrier detection unit 52 checks whether a carrier has been sent from the host.
When a carrier is detected, the process proceeds from step 200 to step 202, and subsequently sent data is received. Then, in step 204, it is determined whether the received data is a selecting frame or not, and if it is a selecting frame, the process proceeds to step 206, in which it is determined whether the node is capable of receiving data from the corresponding host. If reception is not possible, "NAK" is returned in step 208 and the process returns to step 200. In the case of data reception n (, the process advances to step 210 and returns "ACK", and in steps 212 and 214 the reception of data is monitored until timeout. In the case of timeout, the process returns to step 200. When it is sent, Stella 7' is sent from step 212.
Proceeding to 216, the data array is sent to the receive buffer 5jl.
to be received. When data reception is completed, step 218
Then, the check code (BCC code) of the received frame 2
07 to check whether a reception error has occurred in the received frame. If there is no reception error, the process advances to step 220 and "A"
CK'', ends the data reception process, prepares for transmission to the destination specified by the destination address 202, and returns to step 200. If there is a data reception error, the process proceeds to step 222;
It responds with "NAK", invalidates the received frame, returns to step 212, and waits for another frame to be sent. If it is determined in step 204 that a selecting frame has not been received, the process proceeds to step 226 to check whether the received data is a polling frame or an apricot frame. If it is not a polling frame, the process returns to step 200. If it is a polling frame, proceed to step 230;
It is checked whether there is data to be sent from the node to the host, and if there is no data to be sent, the process proceeds to step 246, and "E
Send OT 11 and then--return to step 200. If there is data to be sent, a frame addressed to the host is sent in step 232, and a response to the sent frame is awaited in steps 234 and 236. If there is no response until the timeout, the process proceeds to step 246, and if there is a response, it is checked in step 238 whether the response is "NAK" or "N.A.K.". 'If "NAK", step 238 to step 2
The process returns to step 32 and sends the frame addressed to the host again. If the received data is not ``NAK'', the process advances to step 240 and checks whether it is an ``ACK'' response. If it is an ``ACK'' response, the transmitted frame is erased in step 242 because the frame was sent incorrectly. , the process advances to step 246, sends "E OT", and returns to step 200. If the response is not "ACK" in step 240, it is determined that a communication error has occurred, and the process advances to step 246, and the transmission frame is not erased. All data exchange between a node and a host in the following explanation is performed in one communication, but in the node-to-node communication described below, the data is divided into the following parts and sent multiple times. Therefore, communication between the destination node and the post is performed when all of the divided data has been sent and received. Communication control between each node 1 will be explained below with reference to the flowcharts of FIGS. 8(A) to 8(C). All communications between nodes are performed using packet frames shown in FIG. First, in the eighth +N(A) step 300, the carrier detection unit 523 checks whether a carrier is detected from the communication medium. If a carrier is detected, a packet is subsequently sent, so in step 302 it is checked whether or not the carrier from the communication medium 100a in FIG. 4 has been detected by the transmission circuit A304. If the carrier from the communication medium too b is detected in the transmission circuit B505, the process proceeds to "reception A" shown in FIG. 8(B), which will be described later. Proceed to "B" processing. If no carrier is detected in either step 300, proceed to step 308, check whether there is data to be sent to another note, and if there is no data to be sent, return to step 300, The loop continues until data reception is detected or a transmission request occurs.If there is transmission data in step 308, step 3
Proceed to step 10 to check whether the destination node address is greater than the own node address. In this system, each node address is shown in Figure 4.

[(Connection node address to transceiver A 302 side)<(own node address)<(
connection node address to transceiver B503111)
] This is to determine from which transmission medium the transmission packet should be sent. If the destination address 202 is smaller than the own node in step 310, it is sufficient to send it to the communication medium 100a side, and in step 312 the packet is set in the transmission eight buffer 511 of the transmission circuit A304, and in step 314, the packet is set in the transmitter 511 of the transmission circuit A304. The transmission packet is then transmitted, and the process returns to step 300. When the destination address 202 is larger than the own node address in step 310, it is sufficient to transmit to the communication medium 100b side, and in steps 316 and 318, similarly to steps 312 and 314, transmission circuit B5
05, transmit the packet from transceiver/<8303 and return to step 300. Next, reception processing will be explained. When a carrier is detected from the receiver 100a, the process proceeds to the "reception A" process shown in FIG. 8(B) as described above. First, in step 320, a received packet from the communication medium 100a is sent to the transmission circuit A304 via the transceiver A302.
The received data is received in the receive buffer 521 of. and step 32
2, it is determined by the check code 207 whether a reception error has occurred or not. If a reception error has occurred, the process advances to step 324, and 'NAK' is sent from the transmission circuit A304.
'“, <Prepare to send Kerato, step 32
In step 6, the data stored in the reception buffer 521.\ is invalidated and the process returns to step 300. If no reception error has occurred in step 322, the process proceeds to step 330, where the address data value stored in the address register 522 from the receiving circuit 520 in FIG. Compare and check if the received packet is an "ACK" packet addressed to the own node. If it is an "ACK" packet addressed to the own node, it means that the transmission of the corresponding packet has been completed in step 332, so the packet that matches 46. is cleared, the receive buffer is cleared in step 334, and the process returns to step 300. If it is determined in step 330 that the packet is not addressed to the own node, the process proceeds to step 336, and in the same way as step 320, the comparison unit 524 Addressed to the node “N A K
” Check whether the packet is a device or not. Addressed to own node “NAK”
In the case of a packet, the process proceeds to step 338, where the corresponding packet is retransmitted (preparation for transmission is made, and the process proceeds to step 334). The “ACK” packet and NAK packet in the explanation below are explained in the transmission command 204 shown in FIG.
A K" packet or a NAK'" packet is specified. This transmission command consists of 2 bytes, the first byte is for mate-no-1 interoperability and has the structure shown in Table 2 shown in F. Table 2 The 27th weight is for communication between the packet sending χ node and the packet destination node F, and its configuration is shown in Table 3. Table 3 If it is determined in step 336 that the packet is not addressed to the node itself, the process proceeds to step 340, where it is checked whether the packet is addressed to another mate or not. This is the case of an "ACK/NAK" packet sent from the packet destination node to the packet source mate to indicate whether the received packet is normal or not.This is to request retransmission if the packet sequence numbers are not consecutive. “N.A.K.
If all communications have been successfully completed, an "ACK" packet is sent. In this case, no response is made to the received packet, so the process proceeds to step 348, which will be described later. In step 340, the other node If it is not the destination “ACK/NAK” packet, the process advances to step 342, and the comparing unit 524
It is checked from the output whether the received packet is a data packet addressed to the own node, and if it is a data packet addressed to the own node, the process proceeds to step 344, where it is checked whether it is the last or last piece of communication data. If the communication data is the last, all data communication from the source node has ended normally, so the process proceeds to step 346, where transmission circuit A prepares to send an "ACK" packet from the source node, and returns to step 300, where the preparation is completed. Sends the send packet. If it is not the end of the communication data, the process advances to step 347, where the transmission circuit A304 prepares to transmit an "ACK" packet in response to the received packet. Then, the process proceeds to step 348, and in step 340, “A” is sent to another mate.
CK/NAK" packet, the process similarly proceeds to step 348, where it is checked whether the destination address 202 is larger than the own node address based on the output of the comparator 524. If it is larger than the own node address, Step 3
The process proceeds to step 50, where preparations are made to transmit the received packet from the transmission circuit B505, and the process returns to step 300. If the destination address 202 is smaller than the own node address, the received packet is invalidated and not transmitted to the transmission circuit B505, and the process similarly returns to step 300. This is because there is no node on the communication medium 1oob side that has a node address smaller than its own node address. Further, if the carrier is detected in the transmission circuit B505 in step 302 of FIG. 8(A), the eighth
The process proceeds to the "receiving B" process shown in 1J(C). In the "Receive B" process, the same process as in "Receive A 11" is performed in the transmission circuit B505. However, in the process after step 348 of the "°Receive A" process, the comparison unit 524 compares the destination address 202 with the own node as in step 348. In this case, if the destination address 202 is smaller than the own node address, the received packet is prepared to be transmitted from the transmission circuit A304, and if the destination address 202 is larger than the own node address, The received packet is invalidated.This is because there is no node on the communication medium 1ota side that has a node address larger than its own node address. According to the above, by connecting each transmission device in series via a Q47 medium and setting the transmission device address in order from one end to the other end, the network configuration can be changed. The output direction of the packet can be determined without knowing the ym on each device.
A particular transmission device can exchange packets without affecting the entire network. Therefore, compared to a loop-like configuration, relay 1'f iII'
It is possible to provide a data transmission method that requires less time and delay of 1FIF (and requires less initial investment for network configuration.
i ] J < t im . 2(A) is a diagram showing a packet communication frame in the network system according to the present invention, FIG. 2(B) is a diagram showing details of the address part of the packet frame shown in 21N(A), Figure 3 (A) is a diagram showing a polling frame in communication between a transmission device and a host in a network system according to an uninvented invention, and Figure 3 (B) is a diagram showing a polling frame in communication between a transmission device in a network system and a host in an uninvented Figure 4131 shows the block configuration of the transmission device according to the embodiment of the network system according to the present invention; Figure 4154 shows the details of each part of the transmission circuit V of the transmission device according to the embodiment shown in Figure 4154. Figure 6 shows the communication of the host I connected to the transmission equipment of this embodiment (11)
Figure 7 shows the connection between the unembodied transmission device and the connected host.
II <#Flowchart for importing Il, 8th FA (A
) to (C) are the communication between the transmission devices of this embodiment 4. It is a flowchart which shows the order of ff control. 1×1, 100.100a, 100b, ...communication medium, 101-105.300-/-to, 111 N
114,401-404 *St, 301...Line connection control unit, 302,303...Tora 7 receiver, 3
04,305,322,332.342.352,50
0...Transmission circuit, 306.321,331,341
．． 3j1.501--address setting section, 310...
ilj control unit, 323, 333, 343.353...
Transmission interface, 502... interface section,
510... Transmission m circuit 511... Transmission buffer, 5
20... Reception circuit, 521... Reception buffer, 52
2: address register, 523: carrier detection unit, 524: comparison unit. Figure 1 1 11 (

Claims (2)

[Claims] (1) A plurality of transmission devices are connected in series via a communication medium, and address setting means is provided for setting a unique address to the transmission device, and the address setting means is connected to one end of the transmission device connected in series. A data transmission method characterized in that addresses are set so that the address value increases sequentially from one end to the other. (2) A patent claim characterized in that the transmission device is provided with comparison means for comparing the address value set by the address setting means and the destination address value, and the data transmission direction is determined based on the comparison result of the comparison means. The data transmission method described in item 1.