JPH0117628B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method of generating a token from a lost token state in a loop peer-to-peer communication system using a token method.

(2) Background of technology Recently, as a communication method using one transmission path as a loop network, multiple nodes are placed on the loop network, and data is sent and received between the multiple nodes via the loop network. Large-scale communication methods have been proposed.

A problem with such a loop network communication method is to perform loop access such that data transmitted from multiple nodes do not overlap on the loop.

Various methods have been proposed for such loop access.

The most basic method is to specify that only the parent node in a parent-child relationship among the nodes in the loop network has the right to transmit data. This system has the disadvantage that nodes cannot mutually transmit and receive data.

On the other hand, a time slot method has also been proposed in which multiple nodes are connected on an equal basis in a loop network in which each node transmits data using the time slot assigned to itself. .

This method had the problem of having to keep the loop length constant.

(3) Problems with the prior art Figure 1 shows loop access to explain the conventional time slot method. In this loop access method, the loop is divided into fixed time slots and the data to be transmitted is divided into fixed time slots. It is designed to be loaded into an empty time slot. In other words, in Fig. 1, 1 is a loop network with multiple nodes 2
a, 2b, 2c, 2d, and the transmission time corresponding to the total length of the loop 1 is fixed time slot 3a,
3b, 3c, 3d, 3e, 3f, and each time slot has its own node 2a, 2b, 2c,
In order to divide the message to be transmitted from 2d to other nodes and send it to the loop in data units 5, index data 4 is provided before the data to distinguish whether it is free data or full data, and the message is sent to each time slot. It is designed to be sent out.
For this reason, in the time slot method, the length of the loop 1 must be kept constant, resulting in the disadvantage that the loop length must be adjusted at each node.

In view of these shortcomings, multiple nodes in an equal relationship are connected to the loop network without adjusting the loop length, and only the node that holds the token, which is the right to transmit data, transmits data. There is a loop peer-to-peer communication system. In the case of such a token system, if a token is lost or disappears from the loop network for some reason, any node will no longer have the right to transmit and will be unable to transmit. When such a lost token state occurs, if the node that has issued the transmission request unilaterally generates and holds a token, multiple tokens will be generated on the loop network, making normal communication impossible.

(4) Purpose of the Invention The purpose of the present invention is to provide a system that can efficiently generate tokens without overlapping when a lost token state occurs and restore the system to normal. do.

(5) Structure of the Invention The system of the present invention is a loop network in which a plurality of nodes in an equal relationship are connected to a loop network, and only the node that holds a token, which is the right to transmit data, transmits data. In a communication system, when the token disappears from the loop network,
A node that has received a data transmission request sends a token request frame with its own node address, and when it receives a token request frame sent by another node, the priority of the token request frame is higher than that of the node. If it is large, the token request frame will be sent; if it is small, it will not be sent. When the node receives the token request frame sent by the node, it will generate and hold the token and send data. It is characterized by

(6) Examples of the invention Examples of the invention will be described below with reference to the drawings.

Figures 2a to l are schematic diagrams of loop networks for explaining the method of giving priority to multiple nodes. In Figure 2e, four nodes 2a, 2b, 2c, and 2d are in the loop network 1. When each connected node does not hold a token (the right to send data), it monitors whether a token is being passed to it and sets a priority order for the address for the "token request frame". , for example 2a
>2b>2c>2d.

Next, each node recognizes that the token has disappeared from the loop network if it does not detect the token for a certain period of time using a timer, etc., which will be described later. In this roasted token state, nodes 2a and 2
If a data transmission request occurs at node 2c, token request frames R(A) and R(C) are sent from node 2a and node 2c. As shown in FIG. 3, the token request frame indicates a token and a token request frame in a header (HED) 8 added before the data 5 to be sent, and further includes a source node address (SA) 7 and a destination address. Has node address (DA) 6 and CRC code (CRC)
9. Delimiter (DE) 10 etc. are added as necessary.

At this time, as shown in Figure 2c, node 2b and node 2d receive token request claims R(A) and R(C) sent from node 2a and node 2c, but since there is no particular request, they are relayed as is. do. In this way, as shown in FIG. 2d, the token request frame R(A) from node 2a is sent by node
The token request frame R(C) is received by the node 2a. Node 2a receives the sender node address of the token request frame from node 2c.
It compares SAc with its own node address, recognizes that its own node address has a higher priority than SAc, and absorbs the token request from node 2c.

On the other hand, the node 2c compares the sender node address SAa of the token request R(A) from the node 2a with its own node address, recognizes that its own node address has a lower priority, and receives the token request R( A) is relayed as is on the loop as shown in Figure 2e.

Node 2d is connected to node 2a as shown in FIG. 2f.
A token request frame R(A) is received from
Since there is no particular request, the token request frame R(A) is directly relayed on loop 1.

As shown in FIG. 2g, the node 2a receives the token request frame R(A) sent by its own node and holds the token.

Next, as shown in FIG. 2h, the node 2a sends out the data 5a.

When the node 2a finishes transmitting the data 5a, it sends out a token frame T(A) onto the loop 1 as shown in FIG. 2i.

If there is data to be sent, the node 2b absorbs the token frame T(A) as shown in FIG. 2 j, and the node 2b sends data 5b as shown in FIG. As shown in Figure 1, the token frame T(A) is relayed on loop 1 as it is.

Such operations are sequentially performed at nodes 2c and 2d.

FIG. 4 shows an example of the configuration of the plurality of nodes described above, and the priority communication method of the present invention will be explained based on this system diagram.

When each of the above-mentioned nodes 2a, 2b, 2c, and 2d does not hold a token, it monitors whether or not the token is delivered to its own node, operates the timer 13, and transfers the received token to the transmitter 11. The detection check unit 12 checks the token, and if the token detection check unit does not detect the token for a predetermined period of time set by the timer, it determines that the token in the loop network 1 has disappeared and is in the roast token state, and the data to be sent from each node is determined. If so, the token detection check section sends a token request frame to the token request frame transmitting section 14 (see Figure 3).
By instructing the request, the above-mentioned token request frames R(A), R(C), etc. are sent from the transmitter 15 to the loop network 1. The node that sent the token request frame monitors the received data in the receiving unit 11, and if it receives that the token request frame sent by itself has returned after going around the loop network 1, it holds the token and detects the token. The checking section 12 gives an instruction to the data transmitting section 16 to send the data 5a,
5b is sent to the loop network through the transmitter 15.
When the sending of the data 5a and 5b is completed, the token sending section 17 is instructed to send out the token T(A) through the sending section 15 to the loop network. Furthermore, when the receiving unit 11 receives a token request frame sent by another node, it compares the source node address (SA) 7 with the address of its own node, and detects a token if its own node address is higher by checking the priority order. If the checking unit 12 makes a judgment, it absorbs the received token request frame and does not send out a token request frame from another node to the loop network 1.

If the token detection check unit determines that the source node address of the received token request frame has a higher priority than its own node address, it sends the received token request frame as is to the transmitter and sends it out to the loop network. do.

When a node that does not transmit a token request frame receives a token request frame sent by another node in the receiving section 11, the token detection check section 12 determines the token request frame and sends the token request frame to the transmitting section 1.
5, it is relayed directly to the loop network.

(7) Effects of the Invention As explained above in detail, according to the method of the present invention, when a token disappears for some reason in the token method, only one Since only one node is given a token, there is no confusion in transmission, and the data to be transmitted is not limited as in the time slot type, and it is possible to construct a loop network that can communicate with each other.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional time slot type loop network, FIGS. 2 a to 1 are schematic diagrams explaining the operation of the token type loop network of the present invention, and FIG. 3 is a schematic diagram of the loop network of the present invention. FIG. 4 is a system diagram of each node connected to the loop network of the present invention. 1...Loop network, 2a, 2b, 2c, 2d...
Node, 3a, 3b, 3c, 3d...Time slot, 5, 5a, 5b...Data, R(A), R(C)...
...Token request frame, T(A)...Token frame, 6 (DA)...Destination node address, 7
(SA)... Source node address.

Claims (1)

[Claims] 1. In a loop peer-to-peer communication system in which a plurality of nodes in an equal relationship are connected to a loop network, and only the node that holds a token that is the right to transmit data transmits data, When the token disappears from the loop network,
A node that has received a data transmission request sends a token request frame with its own node address, and when it receives a token request frame sent by another node, the priority of the token request frame is higher than that of the node. If it is large, the token request frame will be sent; if it is small, it will not be sent. When the node receives the token request frame sent by the node, it will generate and hold the token and send data. A loop peer communication system featuring: