JPH0795746B2 - Data communication control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used for data communication control. The present invention relates to a data communication control system of a data transmission system for transferring data in a ring type communication system. In particular, it relates to the resetting method of the primary station.

〔Overview〕

The present invention relates to a data communication control method in a ring communication system in which a large number of nodes are connected in a ring shape by dual clockwise and counterclockwise lines, and a primary station (master station) is automatically set in each circuit. , By setting a new condition that a C frame is transmitted to the opposite line when a data frame does not arrive from the upstream side and the node receiving this C frame is prohibited from becoming the primary station, Even if a data frame cannot normally go around the ring due to an abnormality, the primary station is correctly set and communication can be restarted in a short time.

[Conventional technology]

Conventionally, when performing data transmission in a ring type communication system,
As shown in the figure, one ring-type communication system is provided with one primary station (master station) and multiple secondary stations (slave stations), and the secondary station copies received data while monitoring the reception of control flags. After that, the data of its own station is added and transmitted to the next secondary station.

Further, in the case of line deterioration or line disconnection, it is necessary to set not only one primary station but also a plurality of primary stations, and a method of automatically performing the setting is known. As a condition therefor, (condition 1) when the data frame does not arrive from the upstream station (time out), the secondary station becomes the primary station. However, the timeout time differs depending on each node (priority order).

(Condition 2) When a data frame transmitted from another station is received from the upstream station, the primary station becomes the secondary station.

(Condition 3) Either the clockwise direction or the counterclockwise direction primary station, the control flag in the opposite direction (R flag (flag that turns on when the ring is normally formed))
When it is detected that the control flag (P flag (the flag that turns OFF in a data frame that has not been relayed even once)) is ON when is ON and the direction opposite to the transmission direction is the primary station, the clock It becomes the primary station in both the clockwise and counterclockwise directions.

Has been taken. Under this condition, the primary and secondary stations were reconfigured so that data could be collected.

[Problems to be Solved by the Invention]

In such a conventional ring-type communication system, when the data frame from the primary station cannot normally travel on the ring due to the deterioration of the line or the disconnection of the line, the procedure for switching to the accurate data transmission system is used. There was a problem that wasted operation. That is, if there are only the above-mentioned three conditions, an operation is performed in which nodes are set as primary stations one after another according to the priority order, and then the right of the primary station is transferred to the station having the next priority order, and finally It will take some time for the proper setting of the primary station.

The present invention solves such a problem, and an object of the present invention is to provide a method capable of restarting communication only by a secondary station in a short time even when a data frame from the primary station cannot normally make one round on the ring. To do.

[Means for Solving the Problems]

According to the present invention, a large number of nodes are connected in a ring shape by clockwise and counterclockwise lines, and each node is
There are transceiver stations for clockwise and counterclockwise lines, and each transceiver station has two modes: a primary station mode for generating and transmitting a data frame and a secondary station mode for relaying and transmitting a received data frame. (Condition 1) When there is no data frame from the upstream station within a predetermined time, the secondary station becomes the primary station. However, the predetermined time is set differently for each node and different. (Condition 2) When a data frame transmitted from another station is received from the upstream station, the primary station becomes the secondary station. (Condition 3)
In the node that is the primary station only in one of clockwise and counterclockwise, it is confirmed that the ring is established by the R flag in the line opposite to the line that is the primary station, and When it is recognized from the P flag that the station adjacent on the upstream side of the own station is the primary station, both stations become primary stations on both lines. In the data communication control method in which the above three conditions are set, when each node does not receive a data frame from the upstream side,
A means for transmitting a flag is provided, and as a condition for becoming one of the two modes, (condition 4), when a station opposite to the own node is receiving the C flag, that node becomes the primary station. It is characterized by adding a condition to prohibit.

[Action]

The reset control flags (R flag, P flag, C flag) of the primary station and the secondary station are added to the transmission data frame, the reception data is copied while monitoring the reception of these control flags, and then the own station The data is attached and transmitted to the next secondary station.

Here, the R flag is a flag that turns ON when the data frame has made one round. The P flag is a flag that turns ON if the data frame has not been relayed and is turned OFF when it is relayed. This flag is set to ON when no data frame arrives from.

When the secondary station does not receive the data frame, it switches from the secondary station mode to the primary station mode, and when the primary station receives the data frame of another station, it switches from the primary station mode to the secondary station mode. Also, the R flag is ON when the primary station in one of the clockwise and counterclockwise directions is in the opposite direction,
By detecting P flag OFF, it switches to the primary station mode in both directions, and the C flag in the direction opposite to the own station is ON.
When it is detected, the mode is switched to the secondary station mode.

That is, the same node moves as much as possible to become the primary station for both bidirectional circuits, or the head station of the non-communication line is set as the primary station without the operation of sequentially advancing according to the priority order.

As a result, it is possible to set up a communication system that transmits data in a short time even if the line condition deteriorates or becomes disconnected.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

In the embodiment of the present invention, a large number of nodes A to E are connected in a ring shape by clockwise and counterclockwise lines 21 to 25 and 26 to 30, and each node A to E has a clockwise direction and a counterclockwise direction. Each of the lines 21 to 25 and 26 to 30 is provided with transceiver stations 11 to 15 and 16 to 20.
15 and 16 to 20 have means for setting one of two modes, a primary station mode for generating and transmitting a data frame and a secondary station mode for relaying and transmitting a received data frame. As a condition for any of the modes, (condition 1) the secondary station becomes the primary station when a data frame does not come from the upstream station within a predetermined time. However, the predetermined time is set differently for each node and different.
(Condition 2) When a data frame transmitted from another station is received from the upstream station, the primary station becomes the secondary station. (Condition 3) In the node that is the primary station only in one of clockwise and counterclockwise, it is confirmed that the ring is established by the R flag in the circuit opposite to the circuit that is the primary station. When the P flag recognizes that the station adjacent on the upstream side of the own station is the primary station, both channels become primary stations. In the data communication control system in which the above three conditions are set, each node A to E is connected to the opposite line by C when the data frame does not arrive from the upstream.
A means for transmitting a flag is provided, and as a condition for becoming one of the two modes, (condition 4), when a station opposite to the own node is receiving the C flag, that node becomes the primary station. The condition that prohibits is added.

FIG. 2 is a block diagram showing a concrete configuration example for realizing the embodiment of the present invention. According to this, each node AE
Transmitter stations 11-15 and 16-20 have data lines 21-25
And data transmission connection means 1 for connecting data transmission with 26 to 30, and data frame monitoring means 2 for monitoring the lines 21 to 25 and 26 to 30 to detect deterioration or disconnection, and control. Data transmitting means 8 for monitoring reception of flags (R flag, P flag, C flag), adding data of its own station to a copy of received data, and transmitting the data to the next secondary station;
Timing monitoring means 7 for timing the data transmission and monitoring the flow of data frames, and a secondary station for switching from the secondary station mode to the primary station mode when the transceiver stations 11-15 and 16-20 do not receive the data frame. A primary station mode switching means 4 and a primary station / secondary station mode switching means 5 for switching from the primary station mode to the secondary station mode when the transceiver stations 11 to 15 and 16 to 20 receive data frames of other stations. In addition, the transmitting / receiving station 11 to
15 and 16 to 20 control flags (R flag, P flag, C
Control flag switching means 3 for adding a flag) and the transmitting / receiving station 11 to one of the clockwise direction and the counterclockwise direction.
Primary station mode switching means 6 for switching to bidirectional primary station mode when the data transmitting means 15 and 16 to 20 detect the control flag.

Next, the conventional method described above for comparison will be described with reference to FIG. That is, the state without condition 4 will be described first. In the figure, 11 is a clockwise primary station, and 12 to 15 are clockwise secondary stations. 16 is the counterclockwise primary station, 17
Nos. 20 to 20 are counterclockwise secondary stations. These primary and secondary stations are connected by clockwise and counterclockwise data lines. Here, the clockwise data line and the counterclockwise data line are names given for convenience of distinguishing the data transfer direction.

In such a conventional data transmission method, the primary station and the secondary station are connected in a ring shape by two data lines of clockwise and counterclockwise directions in which the data transfer directions are different from each other, and
Each of the primary station and the secondary station has a function of monitoring the data line and switching between the primary station mode and the secondary station mode when it detects that the line has deteriorated or has become disconnected.

Now, assume that there are three line disconnections as shown in FIG. The priority of timeout is A → B → C →
The order is D → E. At this time, the secondary station 17 is switched to the primary station mode according to the condition 1 (priority order) for resetting the primary station and the secondary station. After that, condition 1 for resetting the primary and secondary stations again
The secondary station 18 switches to the primary station mode according to (priority order). Then, the condition 2 causes the primary station 17 to switch to the secondary station mode, and the condition 3 causes the stations 18 and 13 to become bidirectional primary stations.

Further, the secondary station 19 is switched to the primary station mode according to the condition 1 (priority order) for resetting the primary station and the secondary station. After that, the secondary station 20 is switched to the primary station mode again under the condition 1 (priority order) for resetting the primary station and the secondary station. Then, condition 2 switches the primary station 19 to the secondary station mode, and condition 3 causes 20
Stations 5 and 5 are primary stations in both directions.

In this way, when the data transmission system is disconnected, many steps are required for resuming communication, resulting in wasted time.

On the other hand, in the embodiment of the present invention, the operation of switching the counterclockwise secondary stations 17 and 19 to the primary station mode by the conventional method is not necessary because the counterclockwise data line from both stations is disconnected.

In order to solve this problem, the control flag C flag is set when the line in the direction opposite to the sending direction is in the disconnected state. In this case, the primary station 11 and the secondary stations 13 and 15 have the C flag ON. The primary station 16 in the clockwise direction and the secondary stations 17 and 19 in the counterclockwise direction are in the opposite direction to that of the own station (if the primary station 16 is the primary station 11, if the secondary station 17 is the secondary station 12, if the secondary station 19 is For example, if the C flag in the last data frame received by the secondary station 14) is ON, it will not become the primary station. This is Condition 4 shown below.

(Condition 4) When the C flag in the last received data frame in the opposite direction to the own station is ON, prohibition of becoming the primary station.

Even if a line disconnection as shown in Fig. 3 occurs due to this condition 4, condition 1 (priority order) for resetting the primary station and secondary station
This causes the secondary station 18 to switch to the primary station mode. Further, according to the condition 3, the secondary stations 18 and 13 become the primary stations in both directions. Then, the secondary station 20 is switched to the primary station mode by the condition 1 (priority order). In this way, the steps are shortened and communication can be restarted in a short time.

〔The invention's effect〕

As described above, according to the present invention, in the ring type data transmission system, even if the data frame from the primary station cannot normally make one round on the ring due to the deterioration of the line or the line disconnection, it is set to the secondary station in a short time. Since an appropriate station among the set stations is automatically set as the primary station, there is an effect that communication can be restarted.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of a conventional example and an example. FIG. 2 is a block diagram showing the configuration of a transceiver station according to the embodiment of the present invention. FIG. 3 is a diagram showing a state when a line disconnection occurs in the conventional example and the example. 1 ... Data transmission connection means, 2 ... Data frame monitoring means, 3 ... Control flag switching means, 4 ... Secondary station / primary station mode switching means, 5 ... Primary station / secondary station mode switching means, 6 ... Primary station mode switching means, 7 ... Timing monitoring means, 8 ... Data transmitting means, A, B, C, D, E ...
…node.

Claims (1)

[Claims] 1. A large number of nodes are connected in a ring shape by clockwise and counterclockwise lines, each node is provided with a transceiver station for each clockwise and counterclockwise line, and each transceiver station is Means for setting the primary station mode for generating and transmitting a data frame and the secondary station mode for relaying and transmitting the received data frame are provided. (Condition 1) When no data frame arrives from the upstream station within a predetermined time, the secondary station becomes the primary station. However, the predetermined time is set differently for each node and different. (Condition 2) When a data frame transmitted from another station is received from the upstream station, the primary station becomes the secondary station. (Condition 3) In the node that is the primary station only in one of clockwise and counterclockwise, it is confirmed that the ring is established by the R flag in the circuit opposite to the circuit that is the primary station. When the P flag recognizes that the station adjacent on the upstream side of the own station is the primary station, both channels become primary stations. In the data communication control method in which the above three conditions are set, each node is provided with means for transmitting a C flag to the opposite line when a data frame does not arrive from the upstream side, and either of the two modes is set. As a condition, (condition 4) a condition for adding a condition for prohibiting the node from becoming a primary station when the station around the node is receiving the C flag is added. .