JPH02280435A - Data communication system - Google Patents

Abstract

PURPOSE:To restart communication with a secondary station only even in the occasion of a line is broken controlling the changeover of primary and secondary stations independently of circulation of stations clockwise and counter clockwise respectively. CONSTITUTION:Each data transmitter is provided with a means monitoring a data frame, a means adding a control flag set again by primary stations 1, 6 again into a transmission data frame, a means selecting the primary station mode from the secondary station mode when no data frame is received by secondary stations 2-5, 7-10, and a means selecting the secondary station mode from the primary station mode when the primary stations 1, 6 receive the data frame of the other station, and when the primary stations 1, 6 in either direction of the clockwise direction and the counter clockwise direction in the ring form communication system detect a control flag in the opposite direction, the mode is switched into the primary station mode of both the directions. For example, when 5 node stations A, B, C, D and E are connected as a link. the stations 1-5 in the clockwise direction and the stations 6-10 in the counter clockwise direction are provided as the node stations. Thus, even when the state of line is deteriorated or the line is broken, the ring system for sending a data is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data communication control system for a data transmission system that transfers data in a ring-type communication system.

[Conventional technology]

Conventionally, when transmitting data using a ring-type communication system, one ring-type communication system has one primary station and multiple secondary stations, and the secondary station receives control flags while monitoring them. The data is accumulated, then the own station's data is added and transmitted to the next secondary station.

Reception and transmission are performed sequentially at the next secondary station in the same way, and data from each secondary station can be collected side by side by going around the ring system once.

[Problem to be solved by the invention]

In the conventional system described above, only one primary station is allowed in one ring communication system. Normally, in such a data transmission system in a ring type communication system, the primary station determines the timing of data transmission and monitors the flow of data frames.

Therefore, when the data frame from the primary station cannot normally go around the ring due to line deterioration or line disconnection, the secondary station cannot start communication by itself, and the communication between the secondary stations The disadvantage is that data cannot be exchanged.

[Means to solve the problem]

The present invention provides a data communication method for a ring type communication system, which includes means for monitoring data frames in each data transmission device;
means for adding a control flag for primary station resetting in a transmitted data frame; means for switching from secondary station mode to primary station mode when the secondary station does not receive a data frame; A means is provided for switching from the primary station mode to the secondary station mode when receiving a data frame of Regarding the present invention, a data communication control method is characterized in that a ring system is secured for transmitting data even when the line condition is deteriorated or the line is disconnected by switching to the bidirectional primary station mode by detecting the control flag of the present invention. Details will be explained with reference to the drawings.

First, the conventional method described above will be explained.

FIG. 3 shows the basic configuration of a data transmission system using a conventional ring method. Here, 1 is a primary station, 2 to 5 are secondary stations, and 6 is a data line, and the direction of data transmission is indicated by an arrow.

In this way, each of the primary and secondary stations has separate transmitting terminals and receiving terminals connected to each other, forming a so-called tandem connection.

In the case of this conventional data communication system, only the primary station always initiates data communication. Also, when data is transferred from a secondary station to another station, the primary station must control the data transfer via the primary station.

If a failure occurs in the primary station 1, or if the line 6 deteriorates or is disconnected and data frames are no longer delivered, the secondary station will not be able to transmit data even if it is functioning normally. It disappears.

Next, embodiments according to the present invention will be described.

FIG. 1 shows a data transmission system using this method.

In the data transmission system of FIG. 1, there are five node stations A.

B, C, D and E are connected like a link. In each node station, clockwise stations 1, 2, 3, and 4°5 are called first stations, and counterclockwise stations 6, 7°, 8, 9, and 10 are called second stations, respectively. In the figure, the first station 1 is a clockwise primary station, and the first stations 2 to 5 are clockwise secondary stations. The second station 6 is a counterclockwise primary station, and the second stations 7 to 10 are counterclockwise secondary stations. Numeral 11 is a clockwise data line, and 12 is a counterclockwise data line, each of which transmits different data, and can be transmitted simultaneously.

Here, the clockwise data line and counterclockwise data line are names given for convenience to distinguish the transfer direction of data frames (frame structure will be described later).

In the data transmission system according to the present invention, the first stations 1 to 5v and the second stations 6 to 10 are connected in a ring shape through two data lines, clockwise and counterclockwise, which have different data transfer directions. Each of the node stations A, B, C, D, and E monitors the data line, and when it detects that the line has deteriorated or is disconnected, it switches the first station and second station within the node station to primary station mode and It has a function to switch to secondary station mode.

FIG. 2 shows the configuration of the node station A, in which the node station A is controlled by the switching control means 30 to switch to the first clockwise
It is possible to switch the station 1 and the counterclockwise second station 6 to the primary station mode and the secondary station mode, respectively. Other node stations B, C, D.

Similarly to the node station A, the modes of the first station and the second station of each node station E are controlled by a switching control means.

Figures 4 and 5 show the first and second stations of each node station, respectively.
FIG. 6 is a block diagram showing the structure of the switching control means 30 of each node station.

In this embodiment, the first stations 1, 2, 3.degree. 4.5 in FIG. 1 each have a common function, so for convenience of explanation, their configuration will be explained using FIG. 4 as a representative. The same applies to the second stations 6, 7, 8, and 9.10 in Figure 1, so the fifth station
This will be explained using the figure as a representative. Furthermore, the switching control means 30 of each node station will be explained using FIG. 6 as a representative.

In FIG. 4, the first stations 1, 2, 3, 4 and 5 each include a data receiving circuit 51 for receiving data frames from the clockwise data line 11, and a storage circuit 52 for storing the received data frames. a control circuit 53 that controls data reception and passing to and from the switching control means 30 (FIG. 6) and data frame creation when transmitting own station data;
It includes a start-up circuit 54 for setting data frames to be transmitted at predetermined time intervals when the station operates as a primary station, and a data transmission circuit 55 for transmitting data frames.

In FIG. 5, second stations 6, 7, 8, 9.10 each have a data receiving circuit 61 having the same function as the first station.
, a storage circuit 62, a control circuit 63, a starting circuit 64, and a data transmission circuit 65.

First station 1, 2, 3, 4.5 and second station 6°7.8.9
．． 10 are respectively switched to the primary station and the secondary station under the control of the switching control means 30 shown in FIG.

In FIG. 6, the switching control means 30 controls the interface 3 for receiving and passing data between the first station and the second station.
7, a control flag addition circuit 31 that adds a control flag to be described later, and a data frame monitoring circuit 35 that monitors the contents of a data frame from the first station or second station connected to the interface 37. A first switching circuit 32 that instructs switching from the primary station mode to the secondary station mode, a second switching circuit 33 that instructs switching from the secondary station mode to the primary station mode, and a control circuit 36. including. Under the control of the switching control means 30, the first station 1 and the second station 6 are normally placed in the primary station mode, whereby the stations 1 and 6 transmit data frames to the clockwise and counterclockwise data lines. , and the first stations 2 to 5 and the second stations 7 to 1O are in the secondary station mode and are receiving and transmitting data frames.

FIG. 7 is a diagram showing a data frame.

A data frame consists of six blocks: a start flag 101, a receive address 102, a control flag 103, a data section 104, a frame check section 105, and an end flag 106. A start flag 101 and an end flag 106 indicate the start and end of a data frame, and these flags are always added when each station generates a data frame. The receive address 102 is an address determined by each station. The control flag 103 is a ring flag (RI
This flag controls switching from the primary station to the secondary station and from the secondary station to the primary station. The frame check section 105 is frame check data.

In FIGS. 1 and 4, the primary station 1 sends data frames to the secondary station 2 from the data transmitting circuit 55 at fixed time intervals using the starting circuit 54. Based on the contents of the data storage circuit 52 (data frame from the secondary station 5), the control circuit 53 determines whether the data is sent by the own station or data from another station, or whether the data is sent even after a certain time interval has elapsed. It judges whether the data frame is not returned and sends this information to the switching control means 30 (FIG. 6).

The secondary station 2 receives the data frame coming from the primary station 1 with the data receiving circuit 51, records the data frame in the data storage circuit 52, and at the same time receives the received data received by the data receiving circuit 51 from the data transmitting circuit 55. Send.

When the transmission of this received data is completed, the control circuit 53 generates a data frame containing the own station's transmit data in the data section 104 and the own station's address in the receive address 102, and the data frame is sent from the data transmitting circuit 55. Transmit following the end flag of received data. Note that the data is sent to the control circuit 36 and sent to the data frame monitoring circuit 35.
The contents of the frame are checked, for example whether the ring flag of the control flag is ON or OFF.

Similar to the secondary station 2, the secondary station 3 transmits a data frame containing its own data following the sound of the end flag of the received data from the secondary station 2. Therefore, the data frame is transferred from primary station l to secondary station 2,
After going through steps 3 and 4.5 and returning to the primary station 1, the primary station 1
is the dataing flag (RI) from each secondary station clockwise.
NG FLAG) is generated, and then 1
When transmitting a data frame from the next station 1, the ring flag in the control flag is turned on.

The operations of each station in the clockwise direction described above are similar to the operations of each station in the counterclockwise direction. That is, the primary station 6 collects data from each secondary station 7, 8, 9.
Turn on the flag.

Next, as shown in FIG. 8, a case where a line disconnection occurs at a point P on the clockwise data line ll in the data transmission system of FIG. 1 will be described. At this time, the secondary station 3 cannot receive the data frame from the upstream station even after a predetermined time interval, and the second switching circuit 33 instructs the secondary station 3 to switch to the primary station mode. The first station 3 switches to primary station mode. That is, the switching control affected algae first executes the following control.

Control 1: If no data frame comes from the upstream station (timeout), the secondary station becomes the primary station.

Thus, the secondary station 3 becomes in the primary station mode in the clockwise direction and transmits data frames.

However, for secondary station 8 in the counterclockwise direction, there are still 2
It remains the next station.

Next, when primary station 1 receives a data frame from primary station 3, which has become the primary station under condition l, it sends the data frame.
When it is determined that the frame has been sent from the primary station 3, the primary station 1 enters the secondary station mode according to an instruction from the first switching circuit 32. The switching control ↓sho 30 at this time is referred to as control 2. That is, Control 2: When the upstream station receives a data frame transmitted by another station, the primary station becomes the secondary station.

In this way, the data from the primary station 3 is transmitted to the secondary station 4°5.1.
2 (however, it does not return to primary station 3).

However, in this case, the secondary station 8 in the same node station as the primary station 3
Since the data is terminated at the primary station 6, the secondary station 9,
It is possible to receive data frames from 9.10, but 9.10
Unable to send data frame to. In order to solve this problem, the present invention for the primary station is designed to prevent data frames from the primary station from making one circuit around the ring normally in a ring-type data transmission system due to line deterioration or line disconnection. However, communications can be resumed using only the secondary station.

If it is detected that the ring flag in the control flags of the data frame flowing in the counterclockwise direction is ON,
According to the instruction from the second switching circuit 33, the secondary station 8 in the counterclockwise direction also becomes the primary station, that is, the first and second stations 3 of the node station C
and 8 become the primary station.

As a result, data from the secondary station 8 can also be received by the secondary stations 9 and 10. This case is referred to as control 3.

Control 3: When the primary station is either clockwise or counterclockwise, if it is detected that the RING FLAG is ON in the direction opposite to the primary station (that is, it should be the secondary station), the clockwise direction , becomes the primary station in both counterclockwise directions.

〔Effect of the invention〕 [Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. Figure 2 is a block diagram showing the configuration of each node station in the data transmission system in Figure 1, Figure 3 is a block diagram showing the basic configuration of a data transmission type using a conventional ring type, and Figure 4 is a block diagram of each node station. 5 is a block diagram showing the configuration of the second station of each node station, FIG. 6 is a block diagram showing the switching control means of each node station, and FIG. 7 is a block diagram showing the configuration of the second station of each node station. 8 is a diagram showing a data frame format, and FIG. 8 is a diagram showing a data transmission system when a line disconnection occurs. Agent: Susumu Uchihara, patent attorney, 4. B, C, D, f: Node stations 7.2, 3, 43: Station J at corner 51, 7.8. ? , it)°Z's stray shoulder 1st M2 figure l, l next station Otsu 3, 4. Evening, secondary station 2, data line system 3 Figure M left figure Figure 4 γ Start flannel: /θ? I/Shibuarl/Suf/Male fl'J 'fI'D flak 7 〃4°te part. Nkasa: Funiichimu Sakaki Investigation Department. NZ, Hikari Kinkyo Knock Data Nome Forma, Figure 7

Claims (2)

[Claims] (1) A primary station that starts transmitting data, and multiple secondary stations that collect data from the primary station and secondary stations upstream of their own station and send out the data of the next station after the collected data. In a ring-type communication system consisting of stations with a dual structure of clockwise and counterclockwise rotation, the clockwise and counterclockwise stations each start transmitting data independently, and in the case of the primary station, data transmission begins. a data transmitting means for transmitting data; a data receiving means for receiving data; a data storage means for storing received data; and a control means for switching to a secondary station. In this case, there is a data receiving means that receives data and transparently passes the received data to the transmitting means, a data storage means that stores the received data, and a data storage means that transmits the own station's data after the data received from the upstream station. data transmission means; 1
A data communication system comprising a control means for switching to a next station, and a switching control means for independently controlling switching between clockwise and counterclockwise primary stations and secondary stations as a node station. (2) In a data communication system in a ring type communication system, a means for monitoring whether data is being transmitted to each data transmission device at a predetermined time interval, and a control flag for primary station resetting is added to the transmitted data. means for switching from the secondary station mode to the primary station mode when the secondary station does not receive data; and means for switching from the primary station mode to the secondary station mode when the primary station receives data frames from other stations. In a ring type communication system, the primary station in either direction can switch to the primary station mode in either direction by detecting a control flag in the opposite direction in the clockwise or counterclockwise direction. A data communication control method that is characterized by ensuring a ring system that can transmit data even when the line condition is deteriorated or the line is disconnected.