JPH0438173B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention uses an optical fiber as a transmission line, and uses a time division multiplex communication method to transmit data between a plurality of communication stations connected in a loop through the transmission line. The present invention relates to an information transmission device.

[Prior art]

FIG. 1 is a block diagram showing the system configuration of such an information transmission device, and in the figure, 1a, 1b,
1c and 1d are control units, 2a and 2
b, 2c, 2d are input units, 3a,
3b, 3c, 3d are output units, 4
a, 4b, 4c, and 4d are optical fibers, respectively. Communication station A is controlled by units 1a, 2a, and 3a, communication station B is controlled by units 1b, 2b, and 3b, and communication station B is controlled by units 1c, 2c, and 3b.
3c connects communication station C to unit 1.
d, 2d, and 3d constitute a communication station D, and optical fibers 4a, 4b, 4c, and 4d constitute a loop-shaped transmission line 4. Each of the communication stations A, B, C, and D is also referred to as a node with respect to the transmission path 4.

FIG. 2 is a block diagram showing an example of the configuration of node A, where the same reference numerals as in FIG. .
The opto-electric converter 11a and the electro-optic converter 12a correspond to a demodulator and a modulator when the transmission line is a coaxial line. The configurations of other nodes B, C, and D are also similar to the configuration of node A.

The signal inputted from the optical fiber 4d is converted into an electrical signal by the opto-electrical converter 11a, applied to the serial signal input terminal of the shift register 13a, and shifted within the shift register 13a by a shift clock (not shown) with a predetermined period. , is outputted from the serial signal output terminal of the shift register 13a, converted into an optical signal by the electro-optic converter 12a, and sent to the optical fiber 4a. The input unit 2a writes the signal to be sent to the optical fiber 4a from the parallel signal input terminal of the shift register 13a to the shift register 13a, and the output unit 3a writes the signal sent by the optical fiber 4d into the shift register 13a. read from its parallel output terminals.

FIG. 3 is a format diagram showing a frame of a signal transmitted on the loop-shaped transmission line 4. In the figure, the section indicated by F indicates one frame, and the beginning of frame F is
SY indicates a synchronization slot through which a synchronization signal is transmitted, and CH1, CH2, CH3, and CH4 represent communication slots through which data is transmitted. In the example shown in Figure 3, there are four communication slots in one frame.
Contains CH1 to CH4.

The synchronization signal is made up of a specific bit pattern. By detecting this specific bit pattern, each node knows that it is a synchronization signal, and uses this synchronization signal as a reference to determine the timing of each slot in the frame. You can know the location. Although the synchronization signal may be sent out at any node in the loop-shaped transmission line 4, in the following explanation, it is assumed that node A performs this, and node A will be referred to as a reference node. Furthermore, before node A completes transmission of one frame, the beginning of the frame may be input from node D to the control unit 1a of node A. In such a case, the control unit 1a converts the frames input from node D into 1
When the transmission of the frame is finished and the transmission of the next frame is started, the contents stored at the time are placed on the next frame and transmitted.

If there are four nodes A, B, C, and D as shown in Figure 1, and four communication slots CH1, CH2, CH3, and CH4 as shown in Figure 3, the communication slot allocation method Although there are various methods for this, let us assume that communication slots are fixedly allocated to each node for transmission and reception, as shown in FIG. Figure 4 is a diagram showing the classification of slots used by each node, where T is input unit 2.
R represents a read from the slot to the output unit 3, and L represents a simple relay (i.e., just a shift in the shift register 13). In the example shown in FIG. 4, the synchronization signal is sent by node A, and all other nodes read the synchronization signal to determine the position of each communication slot. Of the communication slots, CH1 is B → A, CH2 is D → B CH3
is A→C CH4 is used for data transmission from C→D.

Fixed assignment as shown in Fig. 4 is the simplest type of assignment.In order to distinguish between each communication slot, an address is assigned to each slot.The address of the communication slot that each node should use for transmission is If there is no double setting in the settings, data transmission will be performed correctly, but if there is a double setting, a malfunction will occur. In order to set the address of the communication slot for each node, it is sufficient to provide the node with a slot position storage device and store the address of the communication slot to be used by the node in this slot position storage device. Each node detects the synchronization signal and determines the position of the communication slot to be used according to the address value stored in the slot position storage device from the time of detection. Therefore,
Dual setting means that slot position storage devices storing the same address value are provided in multiple nodes.

FIG. 5 is a diagram showing double setting of the address of the communication slot, in which the address of CH4 is set twice as T to node A and node C. In the case of such an error, node C is reading CH3, but no other node puts information on CH3,
Furthermore, when node A is transmitting information to node D using CH4, when CH4 enters node C, node C also writes information into CH4 from its input unit 2c via shift register 13c (not shown). This has the disadvantage that the correct information cannot be transmitted due to overwriting.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional system as described above, and it automatically checks in advance that there is no duplicate address setting of the communication slot for each input unit 2a, 2b, 2c, and 2d. The purpose is to provide an information transmission device that can perform

[Embodiments of the invention]

Examples of the present invention will be described below. Also in this invention, the system configuration is as shown in FIG. However, in the device of the present invention, each node is equipped with a storage device for an identification code for identifying the node, and means for writing the contents of this storage device into a communication slot assigned for input from the node. It is assumed that For the identification code of each node, each ROM (read-only memory) that stores each identification code may be added to each node in advance. After configuring the system as shown in Fig. 1, the loop transmission line 4 is For example, under the control of node A, the identification code of each node may be written in a predetermined register of each node. For example, in the system shown in Figure 1, if the identification codes of nodes A, B, C, and D are XA, XB,
It is assumed that these messages, represented by XC and XD, are stored in appropriate registers of each node and are written together with other messages or alone to the communication slot assigned for input from that node.

For example, suppose that the system shown in FIG. 1 is assigned the slots shown in FIG.
Assuming that is the reference node, node A puts a synchronization signal into the synchronization slot and sends it out, and
2 is sent without any signal (all bits remain in the logic 0 state), CH3 is sent with identification code XA, and CH4 is sent without any signal. . When the frame transmitted in this manner reaches the node B, the node B detects the synchronization signal to know the position of each slot, and transmits the frame with the identification code XB placed in CH1. Similarly, node C puts XC into CH4 and sends it out, and node D puts XD into CH2 and sends it out.
When this frame arrives at node A, the contents of each slot are as shown in FIG. Then, in some cases, at node A, node D
The information of the first frame inputted from the frame (with the contents shown in Figure 6) is sent out as is as the second frame, and the output unit of each node assigns it to the input unit of that node. By reading the contents of the slot and detecting that it is the identification code of the node in question, it is possible to know that the slot assignment is correct.

If the communication slots are assigned by mistake as shown in FIG. 5, node A will put the synchronization signal into the synchronization slot and send the code
and send the first frame. Node B
In this case, code XB is put into CH1, but when this frame arrives at node C, the slot
Write code XC to CH4. CH4 already has a code
Although XA had been written, the code XC is overwritten on top of it, so the code XA is erased and the code XC remains. At node D, CH
Since the code XD is written in slot CH2, the information of the first frame that arrived from node D to node A is as shown in Figure 7, and the contents of slot CH3 are blank and the contents of slot CH4 are Node A
Since the code has changed to XC instead of the code XA written in step, it is clear that there is an error in the slot address setting. In this case, the communication slot of node A
Because CH4 has a dual address setting, the error can be detected when the first frame information is sent to node A. However, for example, if node C and D have dual address settings, If it's hot,
When the second frame is sent to node C, the code XD of node D is written in the slot of node C, so the error can be detected at this point.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide an information transmission device that automatically checks whether there is no duplicate address setting of a communication slot for each input unit.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the system configuration of the information transmission device, Figure 2 is a block diagram showing an example of the configuration of node A in Figure 1, and Figure 3 is a frame of a signal transmitted within the system in Figure 1. Figure 4 is a diagram showing the classification of slots used by each node, Figure 5 is a diagram showing the 2nd address of the communication slot.
Figure 6 is a diagram showing the contents of the communication slot when receiving from the reference node when there is no error in the address setting of the communication slot, and Figure 7 is a diagram showing the double setting of the communication slot address. , is a diagram showing the contents of a communication slot in reception of a reference node. 1a, 1b, 1c, 1d... each control unit, 2a, 2b, 2c, 2d... each input unit, 3a, 3b, 3c, 3d... each output unit, 4a, 4b, 4c, 4d... each optical unit. Fiber, A{1a+2a+3a}...Node A, or reference node. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Connect multiple communication stations in a loop through an information transmission path consisting of optical fibers,
In the information transmission device that transmits data between the plurality of communication stations using a time division multiplex communication method, each input unit and the transmission line are provided in each communication station and input information from the communication station to the transmission line. One communication station among the plurality of communication stations is defined as a reference station, and one frame is generated by a synchronization slot into which a synchronization signal is input and a plurality of communication slots at the reference station. means for detecting the synchronizing signal in each of the communication stations and selecting a predetermined communication slot at a predetermined time position using the detection point as a reference; a slot position storage device provided at each of the communication stations for storing the time position of the information input slot assigned to the communication station; and an identification code storage device provided for each of the communication stations for storing the identification code of the communication station; The first frame is sent from the reference station, and the identification code stored in the identification code storage device of each communication station is put into the communication slot selected by the storage in the slot position storage device of each communication station, and the frame is sent to the transmission path. means, the frame circulates through the transmission path and arrives at the reference station, and the frame is circulated as it is again through each communication station, and each communication station checks whether or not its own identification code is stored in its own communication slot. An information transmission device comprising means for detecting whether or not the information input slots assigned to each of the communication stations have dual settings by making a determination.