JPH08149148A - Loop shaped serial communication procedure and loop shaped serial communication network - Google Patents

Abstract

PURPOSE: To realize a loop shaped serial communication procedure and a loop shaped serial communication network in which transmission is started from any node while avoiding the collision of data on a loop. CONSTITUTION: The procedure is a communication procedure in the loop shape serial communication network where plural nodes are connected in a loop, and after specific communication representing the arbitration mode is made from a host control node, a node desiring transmission other than the control node sends a transmission request packet to the control node ((b) (1)) and a node sending the transmission request packet and receiving a transmission enabled signal from the control node makes transmission ((b)(4)).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial loop (seri) in which a plurality of nodes are connected in a loop.
al) A communication network and a communication procedure in this loop-shaped serial communication network.

[0002]

2. Description of the Related Art A LAN (Local Area Network) is known as a device for performing data communication within a certain range. The LAN is used in data communication in various fields.

There are three types of connection methods for each device of this LAN, a star type LAN and a bus type LA.
There is an N, loop (or ring) type LAN. Here, a loop-shaped serial communication network used for a loop type LAN will be considered. The loop here is a ring that has a structure in which a series of elements (devices, data, etc.) are connected, and makes a loop and returns to the original state.

FIG. 6 is a block diagram showing an example of a loop-shaped serial communication network. Here, in order to simplify the explanation,
An example will be described in which the number of nodes (in the network architecture, a component having a function of data communication and data processing, which means a terminal device that performs data communication) is five. However,
In reality, the number of nodes is not limited to this.
Loop 1 is a ring-shaped transmission line as a data transfer means which is the center of a loop-shaped serial communication network, and includes a coaxial cable, an optical fiber, and a twisted pair wire.
cable: twisted pair) etc. Here, the nodes A to E are terminal devices that perform communication, and here, it is assumed that A to E indicate their respective addresses.

Here, it is assumed that data is transmitted counterclockwise. The data transmitted on Loop 1 is
It is assumed to be handled as a packet (packet: data to be transmitted, data exchanged as one unit with destination address and own address). Therefore, each node can know whether or not the packet transmitted via loop 1 is addressed to itself, and the packet not addressed to itself is transmitted to the next node.

In the actual communication, if each node arbitrarily starts the communication, a plurality of packets are overlapped on the loop 1, the data is destroyed and the communication becomes impossible.

Therefore, in order to avoid such a situation,
Some adjustment is required. The following two can be considered as adjustments in such a case. Each node is responsible for not starting transmission while other nodes are transmitting.

Each node allocates a timing at which transmission can be performed. Each node performs transmission within the timing thus assigned.

[0009]

SUMMARY OF THE INVENTION In the above method,
Each node starts transmission after checking the state of Loop 1, but may start transmission at exactly the same timing (this is called “collision”). In such a case, two packets may be overlapped and destroyed on loop 1. Also, if another node is already sending a packet out on loop 1, any node that has a request to transmit must continue to monitor the completion of the other node's transmission. Therefore, there is a drawback that the burden becomes large.

For example, if node B starts transmitting packets to node D and then node B starts transmitting packets to node E, node C will wait until node C finishes transmitting packets to node D. It is necessary to store the packet sent from the node B during that period in its own buffer and to perform the packet transmission to the node E again when the transmission to the node D is completed. Further, if the transmission from the node B is started first, the completion of the communication should be monitored. As described above, there is a drawback that the load on each node becomes large.

In the method, the token (toke
There are also systems that use n) to avoid packet collisions. Here, the token is L
It is used as a "transmission permit" when controlling the transmission right of data in the AN, and only the node holding this token can transmit. When the transmission is completed, the token is put out on the transmission path and the transmission right is abandoned. Since the collision does not occur, the use efficiency of the transmission line is improved. This control method is called token passing.
We call it the method. However, there is a problem in that management of tokens (countermeasures against failures (double occurrence or disappearance of tokens due to noise, etc.) becomes complicated and requires devising.

Further, in the above method, a specific node is defined as a host (control node), and only this control node has the authority to start communication. That is, only the host can perform transmission to each node at free timing, and the node to which the communication is sent returns the communication to the host, thereby completing one set of communication. Therefore, a node (general node) other than the host can start transmission only in the form of a reply. For example, in FIG. 6, the node A is defined as a host, and the other nodes B to E are in a state of waiting for communication from the node A.

With such a configuration, for example,
If the host wants to know immediately about an anomaly detected by a node other than the host, the host must continue to communicate with the node that may have the anomaly even if the anomaly is rare. I have a problem.

The present invention has been made to solve the above problems, and an object of the invention is to perform loop serial communication capable of starting transmission from any node while avoiding data collision on the loop. It is to realize a procedure and a loop-shaped serial communication network.

[0015]

The first means for solving the above-mentioned problems is a communication procedure in a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and arbitration is performed from a control node serving as a host. After a specific communication indicating the mode, the node other than the control node that wants to transmit transmits a transmission request packet to the control node, and the node that has transmitted the transmission request packet,
The loop serial communication procedure is characterized in that the node which receives the transmission permission signal from the control node performs transmission.

A second means for solving the above-mentioned problem is a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and when the transmission from another node can be permitted, an arbitration mode is set. A control node that sends out an arbitration start packet indicating that is to each node, and sends a transmission permission signal to a node that arbitrates and permits transmission when receiving a transmission request packet from each node, A node that transmits a transmission request packet to the control node when there is a request to perform data transmission after receiving the arbitration start packet and that transmits after receiving a transmission permission signal from the control node. It is a characteristic loop-shaped serial communication network.

A third means for solving the above-mentioned problem is a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and the arbitration mode is set when transmission from another node can be permitted. A node that transmits an arbitration start packet indicating that the transmission request packet is sent to each node, and when the transmission request packet is received from each node, arbitration is performed according to the level information in the transmission request packet to permit transmission. Control node that sends a transmission permission signal to a node that permits transmission, and controls a transmission request packet containing predetermined level information when there is a request to perform data transmission after receiving an arbitration start packet. A loop-shaped serial communication network comprising: a node that transmits to a node and that transmits after receiving a transmission permission signal from a control node. .

A fourth means for solving the above-mentioned problem is a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and the arbitration mode is set when transmission from another node can be permitted. A control node that sends out an arbitration start packet indicating that is to each node, and sends a transmission permission signal to a node that arbitrates and permits transmission when receiving a transmission request packet from each node, When a request for data transmission is received after receiving an arbitration start packet, a transmission request packet is sent to the control node, and a transmission permission signal from the control node is received and then transmitted to other nodes than the control node. A loop-shaped serial communication network comprising:

[0019]

In the loop-shaped serial communication procedure which is the first means for solving the problem, the node other than the control node wants to perform transmission after the specific communication indicating the arbitration mode is received from the host control node. Sends a transmission request packet to the control node. Then, the node that has received the transmission permission signal from the control node transmits the signal. This makes it possible to start transmission from any node while avoiding data collision on the loop.

In the loop-shaped serial communication network which is the second means for solving the problem, an arbitration start packet indicating the arbitration mode when the transmission from another node can be permitted is sent from the control node to each node. Sent to.
When there is a request to perform data transmission after receiving an arbitration start packet, a transmission request packet is sent from the node to the control node, and the control node that receives this transmission request packet arbitrates to the node that permits transmission. A transmission permission signal is sent to the device. Then, the node that has received the transmission permission signal from the control node transmits the signal.
This makes it possible to start transmission from any node while avoiding data collision on the loop.

In the loop-shaped serial communication network which is the third means for solving the problem, an arbitration start packet indicating the arbitration mode is sent from the control node to each node when transmission from another node can be permitted. Sent to.
The node receiving the arbitration start packet sends a transmission request packet including level information predetermined for each node to the control node when there is a request for data transmission.
The control node which receives this transmission request packet performs arbitration according to the level information of each node to determine the node to which the transmission is permitted, and sends the transmission permission signal to the permitted node. Then, the node that has received the transmission permission signal from the control node transmits the signal. This makes it possible to start transmission from any node while avoiding data collision on the loop.

In the loop-shaped serial communication network which is the fourth means for solving the problem, an arbitration start packet indicating the arbitration mode is sent from the control node to each node when transmission from another node can be permitted. Sent to.
When there is a request for data transmission after receiving an arbitration start packet, a transmission request packet is sent from the node to the control node, and when this transmission request packet is received, the control node performs arbitration and permits transmission. A transmission permission signal is sent to. Then, the node that has received the transmission permission signal from the control node transmits to another node. This makes it possible to start transmission from any node to another node while avoiding data collision on the loop.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, with reference to FIGS. 1A and 1B, a basic principle operation of the loop serial communication procedure of the present invention will be described.

Here, FIG. 1A is a flow chart showing a processing procedure between the control node and the general node, showing a principle processing procedure when transmission is performed from the control node side in a state other than the arbitration mode. . Further, FIG. 1B is a flowchart showing a processing procedure in principle between the control node and the general node, in the case of transmitting from the general node side during the arbitration mode.

In this case, one of the specific nodes is defined as a host (control node). Then, in the normal state (states other than the arbitration mode), only the control node has the authority to start communication. That is, only the control node can transmit to each general node at any timing (FIG. 1 (a) (1)), and the node to which the communication is sent performs the processing and returns the communication to the control node. This completes one set of communication (FIGS. 1 (a) and (2)). Therefore, nodes other than the control node can start transmission only in the form of reply.

In a state other than the normal state (called an arbitration state in this embodiment), one of the general nodes transmits a transmission request packet to the control node (FIG. 1 (b)).
(1)), whereby the control node notifies each general node that the arbitration mode is terminated (FIG. 1 (b) (2)),
The general node that has received the permission (FIG. 1 (b) (3)) transmits after the permission (FIG. 1 (b) (4)) to complete one set of communication. In FIG. 1B, it is assumed that the general node that has transmitted the transmission request packet has been permitted.

Therefore, as described above, the time other than when the host is transmitting is set as the arbitration mode, and the host detects and arbitrates the transmission request packet in the arbitration mode, so that the general node other than the host can always make a request. You will be able to send. As a result, the host does not need to call the general node at regular intervals, and the load on the host and the frequency of loop usage are reduced. Then, for the general node, the operation for avoiding the data collision is only for the transmission request packet, and for the other packets, the switch may be in the loop connection state, which reduces the load on each general node. .

FIG. 2 is a block diagram showing the configuration of a node which is the main part of the loop-shaped serial communication network, and FIG. 3 is a block diagram showing the overall configuration of the loop-shaped serial communication network. Here, FIG.
The configuration of the loop serial communication network will be described with reference to FIG. Here, in order to simplify the description, a case where the number of nodes (terminal devices that perform communication) is 5 will be described as an example. However, actually, the number of nodes is not limited to this. The loop 1 is a ring-shaped transmission line as a data transfer means that is the center of the loop-shaped serial communication network, and is composed of a coaxial cable, an optical fiber, a twisted pair wire, and the like. Nodes 10, 11, 12, 1
Reference numerals 3 and 14 denote terminal devices that perform communication, and here, it is assumed that numbers 10 to 14 indicate respective addresses.

Each node controls a switch for connecting / disconnecting the loop 1, a transmission / reception device for controlling transmission / reception of packets (data to be transmitted, a destination address and a lump of data with its own address), and a switch. It also has a CPU for managing packets. In FIG. 2, the node 10 is illustrated, and the switch 1
0a, a transmitting / receiving device 10b, and a CPU 10c are shown.

Here, it is assumed that data is transmitted counterclockwise on loop 1. Data transmitted on the loop 1 is treated as a packet. Therefore, each node can know whether or not the packet transmitted via the loop 1 is addressed to itself, and the packet not addressed to itself is transmitted to the next node.

Further, in this embodiment, one of the specific nodes is defined as a host (control node). Then, in the normal state, only the control node has the authority to start communication. That is, only the host can perform transmission to each node at free timing, and the node to which the communication is sent returns the communication to the host, thereby completing one set of communication. Therefore, nodes other than the host can start transmission only in the form of a reply.

Further, in a state other than the normal state (which is called an arbitration state in this embodiment), one of the general nodes transmits a transmission request packet to the host, and when the transmission is permitted, the transmission is carried out for one set. Communication is completed.

Here, it is assumed that the node 10 is a host as a control node and the other nodes 11 to 14 are general nodes. Next, with reference to FIG. 4 which is a flowchart showing the processing procedure of the general node and FIG. 5 which is a flowchart showing the processing procedure of the control node, the loop serial communication procedure of the embodiment of the present invention will be described.

Here, the flow of the loop serial communication procedure will be described with reference to FIGS. 4 and 5. Here, FIG.
Indicates a communication procedure of a general node (hereinafter, simply referred to as a node) other than the control node. Further, FIG. 5 shows a communication procedure on the control node side.

When the host wants to perform transmission (step (1) in FIG. 5), if the host is in an arbitration state, it transmits an arbitration end signal (steps (2) and (3) in FIG. 5), and then the content to be transmitted The packet including the data of is transmitted (step (4) in FIG. 5). If it is not in the arbitration state, the packet is transmitted as it is.

When it becomes unnecessary to particularly actively transmit, an arbitration start packet is transmitted to each node (step (6) in FIG. 5) to notify that the mode has been changed to the arbitration mode. This arbitration start packet is common to each node.

The node that received any packet (see FIG.
In step (1), the destination address of the packet is checked (step (2) in FIG. 4), and if the packet is addressed to another node, it is transferred to the next node (step (3) in FIG. 4).
If the received packet is an arbitration start packet (step (4) in FIG. 4), the switch is put in the loop disconnection state and the arbitration mode is waited (step (5) in FIG. 4).

That is, the switch of each node is set to the loop disconnection state, and the packet received from the reception terminal R of the transmission / reception device is processed by the CPU if it is addressed to itself, and responsibly if the packet is addressed to another node. It is ready to be transferred to the next node.

In this arbitration mode, the node that wants to transmit (step (8) in FIG. 4) transmits a transmission request packet (steps (9) and (10) in FIG. 4). This transmission request packet includes a destination address, a source address, data indicating a transmission request, and level information predetermined for each node, but it is a packet having a much smaller size than a packet including general data. . Therefore, the load on each node in the arbitration mode is limited to a very small one.

As the level information included in the transmission request packet, the source node name (number) and data determined according to the transmission content can be considered. This allows the control node to set the priority order when the transmission request packets are generated almost at the same time. However, if the size of this level information becomes too large, it is expected that the transmission request packets from multiple nodes will collide during the arbitration mode, so it is necessary to keep the level information to a minimum. There is.

During the arbitration mode (step (5) in FIG. 5),
Upon receiving such a transmission request packet (step (5) in FIG. 5), the host transmits an arbitration end packet to each node (step (8) in FIG. 5).

Receiving this arbitration end packet, each node sets the switch in a loop connection state and returns from the arbitration mode to the normal mode (steps (6) and (7) in FIG. 4). And
The host communicates with the node (requesting node) that has output the transmission request packet (step (9) in FIG. 5, steps (11), (12), and (1) in FIG. 4).
3)). When a transmission request packet is transmitted from some nodes in the arbitration mode, the host determines the priority by referring to the level information included in the transmission request packet. Therefore, the arbitration can be quickly performed by this level information. Then, for example, it is possible to permit the transmission according to the priority order.

When the required communication is completed, the requesting node switches the switch to the loop connection state and returns to the normal state (step (14) in FIG. 4). Therefore, the arbitration mode is provided as described above, and the host detects the transmission request packet in the arbitration mode,
By arbitrating, it becomes possible to perform transmission at any time by a request from a general node other than the host. As a result, the host does not need to call the general node at regular intervals, and the load on the host and the frequency of loop usage are reduced. Then, for the general node, the operation for avoiding the data collision is only for the transmission request packet, and for the other packets, the switch may be in the loop connection state, which reduces the load on each general node. .

In the above embodiments, the case where the communication between the host and the general node is performed has been described. Instead of such communication between the host and the general node, communication between the respective nodes (general nodes) may be performed.

As described above, it is necessary to have a control node (host or arbiter) for transmitting arbitration start and end packets even when performing communication between general nodes. is there. Then, this control node gives permission to the node that transmitted the transmission request packet. In the case of communication from the host to the general node, communication was performed in the form of a reply after permitting transmission, but when communicating between nodes, the control node also transmits a transmission permission signal (transmission) to the node that transmitted the transmission request packet. Permission packet). Then, the node that receives this transmission permission signal communicates with other nodes.

When the general nodes shown here are communicated with each other, the level information included in the transmission request packet is simply the source node as in the above description of the embodiment of the communication between the general node and the control node. Name (number) only, source node name and destination node name, or what you want to send (error: error)
The contents can be incorporated to some extent, and various modifications and contents can be added. This allows the control node to determine transmission permission and priority for communication between nodes. However, if the size of this level information becomes too large, it is expected that the transmission request packets from multiple nodes will collide during the arbitration mode, so it is necessary to keep the level information to a minimum. There is.

Further, in each of the above embodiments, the arbitration start packet and the arbitration end packet may be of a form that is commonly transmitted to all nodes at once (common packet).
The format may be such that the host or arbiter individually transmits to each node.

As described in detail above, in the communication procedure in the loop serial communication network in which a plurality of nodes are connected in a loop, a specific communication indicating that the control node as the host is in the arbitration mode is performed. After that, the node other than the control node that wants to transmit transmits a transmission request packet to the control node, and the node that has transmitted the transmission request packet and that has received the transmission permission signal from the control node is According to the loop-shaped serial communication procedure characterized by performing transmission, it becomes possible to start transmission from any node while avoiding data collision on the loop.

Further, in a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and an arbitration start packet indicating that the arbitration mode is in the arbitration mode when transmission from another node can be permitted. A control node that sends to a node and sends a transmission enable signal to a node that performs arbitration and permits transmission when receiving a transmission request packet from each node and data transmission after receiving an arbitration start packet. A loop-type serial communication network characterized by comprising a node that transmits a transmission request packet to a control node when there is a request to perform, and transmits after receiving a transmission permission signal from the control node. In this case, it becomes possible to transmit at any time by a request from a general node other than the control node, which eliminates the need for the host to call the general node in a fixed cycle, and The frequency of use of the burden and the loop of the node is reduced. Then, for the general node, the operation for avoiding the data collision is only for the transmission request packet, and for the other packets, the switch may be in the loop connection state, which reduces the load on each general node. .

An arbitration start packet indicating that the arbitration mode is in the loop serial communication network in which a plurality of nodes are connected in a loop and when transmission from another node can be permitted is transmitted. When sending to a node and receiving a transmission request packet from each node, arbitration is performed according to the level information in this transmission request packet to determine the nodes to which the transmission is permitted, and to the nodes that permit the transmission. To the control node which sends a transmission permission signal to the control node, and when there is a request to perform data transmission after receiving the arbitration start packet, the control node sends a transmission request packet containing predetermined level information to the control node. According to a loop-shaped serial communication network characterized by including a node that transmits after receiving a transmission permission signal of Will be able to transmit at any time request from over de, it eliminates the need for the control node is called a normal node at a constant period, reducing the frequency of use of the burden and the loop of the host. And for general nodes,
The operation for avoiding data collision is only for the transmission request packet, and for the other packets, the switch may be in the loop connection state, which reduces the load on each general node. Further, even when the transmission start request packets from the general nodes compete, it becomes easy to perform arbitration based on the level information.

Further, in a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and an arbitration start packet indicating that the arbitration mode is in an arbitration mode when transmission from another node can be permitted. A control node that sends to a node and sends a transmission enable signal to a node that performs arbitration and permits transmission when receiving a transmission request packet from each node and data transmission after receiving an arbitration start packet. A node that sends a transmission request packet to the control node when there is a request to perform, and that transmits to a node other than the control node after receiving a transmission permission signal from the control node. According to the characteristic loop-shaped serial communication network, it becomes possible to perform transmission between general nodes in response to a request from a general node other than the control node. The frequency of use of the collateral and the loop is reduced. Then, for the general node, the operation for avoiding the data collision is only for the transmission request packet, and for the other packets, the switch may be in the loop connection state, and the load on each general node is reduced. .

[0052]

As described above in detail, in the loop-shaped serial communication procedure and loop-shaped serial communication network of the present invention, after the specific communication indicating the arbitration mode from the host control node, A node other than the control node that wants to transmit transmits a transmission request packet to the control node, and the node that has transmitted the transmission request packet and that has received the transmission permission signal from the control node performs transmission. According to the loop-like serial communication procedure characterized by this, it is possible to start transmission from any node to the control node or other general nodes while avoiding data collision on the loop. become.

Further, by adding level information such as the node number to the transmission start request packet, the control node determines the priority of the node which starts the transmission even when the transmission start requests from the general nodes conflict. It becomes easier and arbitration can be performed quickly.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure between a control node and a general node according to an embodiment of the present invention, wherein FIG. 1A is a flowchart showing the processing procedure when transmission is performed from the control node side. b) is a flow chart showing a processing procedure when transmission is performed from the general node side.

FIG. 2 is a configuration diagram showing a configuration of a node used in an embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration example of a loop-shaped serial communication network of the present invention.

FIG. 4 is a flowchart showing a processing procedure of a control node according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a processing procedure of a general node according to an embodiment of the present invention.

FIG. 6 is a configuration diagram showing a configuration example of a conventional loop serial communication network.

[Explanation of symbols]

 1 loop 10 to 14 nodes 10a switch 10b transmitting / receiving device 10c CPU

Claims (4)

[Claims] 1. A communication procedure in a loop-shaped serial communication network in which a plurality of nodes are connected in a loop, wherein a control node is provided after a specific communication indicating that it is in an arbitration mode from a control node serving as a host. Other than the above, the node that wants to transmit transmits a transmission request packet to the control node, and the node that has transmitted the transmission request packet and that has received the transmission permission signal from the control node performs transmission. Loop-like serial communication procedure. 2. A loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and an arbitration start packet indicating that the arbitration mode is in an arbitration mode when transmission from another node can be permitted. A control node that sends a transmission request signal to a node, performs arbitration when receiving a transmission request packet from each node, and sends a transmission permission signal to the node that permits transmission, and data transmission after receiving an arbitration start packet. A loop-shaped serial communication network, comprising: a node that transmits a transmission request packet to a control node when there is a request to perform, and transmits after receiving a transmission permission signal from the control node. 3. A loop-shaped serial communication network in which a plurality of nodes are connected in a loop, and an arbitration start packet indicating that the arbitration mode is in an arbitration mode when transmission from another node can be permitted. When sending to a node and receiving a transmission request packet from each node, arbitration is performed according to the level information in this transmission request packet to determine the nodes to which the transmission is permitted, and to the nodes that permit the transmission. To the control node, which sends a transmission permission signal to the control node, and when there is a request to perform data transmission after receiving the arbitration start packet, the control node sends a transmission request packet containing predetermined level information to the control node. And a node which transmits after receiving the transmission permission signal of the loop serial communication network. 4. A loop serial communication network in which a plurality of nodes are connected in a loop, and an arbitration start packet indicating that the arbitration mode is in an arbitration mode when transmission from another node is permitted. A control node that sends a transmission request signal to a node, performs arbitration when receiving a transmission request packet from each node, and sends a transmission permission signal to the node that permits transmission, and data transmission after receiving an arbitration start packet. A node that sends a transmission request packet to the control node when there is a request to perform, and that transmits to a node other than the control node after receiving a transmission permission signal from the control node. A characteristic loop-shaped serial communication network.