JPH0744549B2 - Data transmission device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data transmission device for performing data transmission between a plurality of communication nodes via a transmission control device coupled to a data way.

(Prior Art) When data transmission is performed using a data way, data is transmitted by being carried on a series of signals called frames. The transmitted frame is processed by the transmission control device. In addition to data, information to be exchanged between communication nodes, for example, information such as line quality, line length, line disconnection, and transmission distortion (these are referred to as line system information) is written in the frame.

(Problems to be Solved by the Invention) As described above, in the conventional transmission method in which line-type information is written in addition to data in a part of the frame and is transmitted, on the transmitting side, the line-type information is stored in the frame. And a circuit for reading and reproducing reline information from the frame on the receiving side. Therefore, there is a problem that the structure of the device becomes complicated and the transmission control becomes complicated.

The present invention has been made in view of such problems,
It is an object of the present invention to provide a data transmission device having a simple structure and easy transmission control.

(Means for Solving the Problems) The present invention for solving the above problems is a data transmission device for performing data transmission between a plurality of communication nodes via a transmission control device coupled to a data way. The minimum frame length of normal communication performed by the device is specified, and the line information is a frame having a length equal to or less than the minimum frame length, and the frame transmitted by the transmission control device to the line coupling unit coupled to the data way is transmitted. Frame length identification circuit (14) that identifies normal communication or communication with line information by identifying the length of the line, and line monitoring circuit (13) that monitors the presence or absence of transmitted signals.
When the frame length identification circuit identifies normal communication, a normal communication frame is input, the decoder (12) that decodes it and outputs it to the transmission control device, and the frame length identification circuit carries out communication with line system information. If you have identified, enter the frame with the line information,
Line information discriminating circuit for discriminating line information (15)
, A coder (16) for converting information to be transmitted from the transmission control device into a signal of a predetermined form, and a line system information generation circuit (17) for generating line system information.
And a switch (18) for selecting a signal from the coder and a signal from the line-related information generating circuit and transmitting the signal to the data way, and a drive circuit (19) for this switch. The drive circuit (19) is When sending line information, check the signal from the line monitoring circuit, wait for the end of arrival of the signal if the signal is present on the data way, and immediately switch the line if there is no signal on the data way. Connect so as to select the signal from the system information generation circuit, check the information from the line system information discrimination circuit during normal communication frame transmission, output a transmission permission signal to the transmission control device, and switch from the coder. The data transmission device is characterized in that the signals are connected so as to be selected.

(Embodiment) FIG. 1 is a conceptual diagram of a communication system to which the present invention is applied. In the figure, WY is a data way, which is a loop type here. LC1, LC2 ... are all line joints, CNT
1, CNT2 ... are transmission control devices, and ST1, ST2 ... are communication nodes. Each communication node ST1, ST2 ... Is a transmission control device C
Time division multiplex communication is performed via the NT and line coupling section LC data way WY.

FIG. 2 is a configuration block diagram of a main part of each line coupling part LC1, LC2 ... In the figure, 11 is a receiver that receives a signal transmitted via a data way WY, and 12 is a receiver 11
Decoder connected to the output terminal of, 13 is a line monitoring circuit that monitors the presence or absence of an input signal to the receiver 11, 14 is a receiver
A frame length identification circuit for identifying the length of the frame received in 11 and a line system information identification circuit 15 for identifying the content of line system information such as line quality, line length, and transmission distortion. The decoder 12 and the line system information discriminating circuit 15 are controlled in operation and non-operation by a signal from the frame length identifying circuit 14. 16 is a coder for converting information to be transmitted from the transmission control device CNT into a signal of a predetermined form, 17 is a line system information generation circuit for generating line system information, 18 is a contact point a, b, the signal from the coder 16 And a switch for selecting a signal from the line information generating circuit 17, 19 is a drive circuit for the switch 18, which is a signal from the line information discriminating circuit 15, a signal from the line monitoring circuit 13, and a transmission request from the transmission control device CNT. Input the signal, drive signal of switch 18, and transmission control device CNT
The transmission request signal is output to. A transmitter 20 outputs the signal selected by the switch 18 to the data way WY.

FIG. 3 is an explanatory diagram showing a form of a signal transmitted on the data way WY. In the figure, (a) shows a frame of normal communication performed by the transmission control device CNT, and the minimum length of this frame is defined as a predetermined length Lf. (B) shows a line system frame for exchanging unique information (line system information) between the communication nodes. The length Ll of this line system frame is selected to be smaller than the minimum length Lf of the frame for normal communication.

The operation of the apparatus configured as described above will be described below by dividing it into a normal communication frame receiving operation, a line information sending operation, and a normal communication frame sending operation.

(Frame Reception Operation of Normal Communication) FIG. 4 is an operation waveform diagram in this operation state.

Receiver 11 was transmitted via data way WY (a)
Receive a signal as shown in. In the received signal, a normal communication frame 31 and a line system frame 32 are mixed between the communication frames. The frame length identification circuit 14
The frame length of the signal received by the receiver 11 is monitored, and if the frame length is larger than the predetermined minimum frame length Lf, the frame is identified as a normal communication frame, and the frame length is smaller than the predetermined minimum frame length Lf. In this case, the frame is identified as a line frame. Here, if the frame is identified as a normal communication frame, a signal indicating that is output as shown in (b), and the decoder 12 operates. The decoder 12 inputs a normal communication frame as shown in (c), decodes it, and outputs its output to the transmission control device CNT side. Also, if it is identified as a line-type frame,
As shown in (d), a signal to that effect is output, and the line-related information discriminating circuit 15 operates according to this, discriminates the line-related information, and outputs the discrimination result to the drive circuit 19.

In such a normal communication frame receiving operation state, it is equivalent to transmitting only a normal communication frame between the communication nodes from the higher-level transmission control device CNT side.

(Line-related information transmission operation) FIG. 5 is an operation waveform diagram in this operation state.

For example, depending on the line situation such as cable cutting,
When the line information transmission request is generated as shown in (a), the drive circuit 19 checks the output signal from the line monitoring circuit 13 shown in (c). Then, as shown by the solid line in the figure, when a signal exists on the data way WY,
As shown by the solid arrows in (c) and (d), after waiting for the end of the normal communication frame, the switch 18 is connected to the contact b side, and the line information from the line-related information generating circuit 17 is transferred to the transmitter 20. To the data way WY via. Further, as a result of checking the output signal from the line monitoring circuit 13, when there is no signal on the data way WY as shown by the broken line in (c), the switch 18 is immediately sent as shown by the broken line in (d). Is connected to the contact b side, and the line information from the line system information generating circuit 17 is sent to the data way WY via the transmitter 20. As described above, the line information transmission operation is performed on the transmission control device side without any awareness.

(Normal Frame Transmission Operation) FIG. 6 is an operation waveform diagram in this operation state.

When a transmission request is issued from the higher-order transmission control device CNT side, as shown in (a), the drive circuit 19 checks the information from the line system information determination circuit 15 and finds that the line status is normal. When confirmed, the transmission permission signal is output to the higher-level transmission control device CNT as shown in (b), the switch 18 is connected to the contact a side, and the normal communication frame is connected as shown in (c). The data is sent to the data way WY via the transmitter 20.

It should be noted that although the specific configurations of the transmission control device CNT and the upper communication node have not been described above, it is assumed that known ones are used as they are.

(Effects of the Invention) As described above, according to the present invention, the minimum length of a frame for normal communication is defined, the information of the line system is set to a length equal to or shorter than the minimum frame length, and the frame length identification circuit sets the transmitted frame. The information of normal communication and the information of line system are separated according to the length of. Therefore, according to the present invention, it is possible to deal with line system problems such as line length change, transmission distortion, and line disconnection by the line coupling unit, and a data transmission device having a simple configuration and easy transmission control is provided. realizable.

Further, in the present invention, the transmission of line-related information can be performed in the line coupling section without the control from the transmission control device.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the configuration of a communication system to which the present invention is applied, FIG. 2 is a configuration block diagram of a main part of each line coupling unit, and FIG. 3 is an explanatory diagram showing a form of a signal transmitted on a data way. , FIG. 4 to FIG. 6 are waveform charts for explaining each operating state. WY ... Data way, LC ... Line coupling part, CNT ... Transmission control device, ST ... Communication node, 11 ... Receiver, 12 ...
Decoder, 13 line monitoring circuit, 14 frame length identifying circuit, 15 line information discriminating circuit, 16 coder, 17 line information generating circuit, 18 switch, 19
...... Drive circuit, 26 …… Transmitter.

Claims (1)

[Claims] 1. A data transmission device for performing data transmission between a plurality of communication nodes via a transmission control device coupled to a data way, wherein a minimum frame length of normal communication performed by the transmission control device is defined and a line system is provided. Information is a frame having a length less than or equal to the minimum frame length, and the transmission control device adds normal communication or line-related information by identifying the length of the transmitted frame to the line coupling unit coupled to the data way. Frame length identification circuit (14) for identifying whether communication has been performed, and line monitoring circuit (13) for monitoring the presence or absence of transmitted signals
When the frame length identification circuit identifies normal communication, a normal communication frame is input, the decoder (12) that decodes it and outputs it to the transmission control device, and the frame length identification circuit carries out communication with line system information. If you have identified, enter the frame with the line information,
Line information discriminating circuit for discriminating line information (15)
, A coder (16) for converting information to be transmitted from the transmission control device into a signal of a predetermined form, and a line system information generation circuit (17) for generating line system information.
And a switch (18) for selecting a signal from the coder and a signal from the line-related information generating circuit and transmitting the signal to the data way, and a drive circuit (19) for this switch. The drive circuit (19) is When sending line information, check the signal from the line monitoring circuit, wait for the end of arrival of the signal if the signal is present on the data way, and immediately switch the line if there is no signal on the data way. Connect so as to select the signal from the system information generation circuit, check the information from the line system information discrimination circuit during normal communication frame transmission, output a transmission permission signal to the transmission control device, and switch from the coder. A data transmission device, characterized in that it is connected so as to select the signal of.