JPS63136175A - Loop type data transmission equipment - Google Patents

Abstract

PURPOSE:To improve the efficiency of data transmission by sharing an information area and at the same time transmitting alarm information only when an alarm state is changed in each terminal equipment to reduce the occupation rate of the information area and to increase the occupation rate of a data area respectively. CONSTITUTION:Information received through a transmission line L is sent to a transmission/reception circuit 3 via a code converting circuit 1 and a synchronizing circuit 2. The data is transferred to a data transmission/reception device (not shown here) via an interface circuit 4 and a transmission frame formed by the circuit 3 is transmitted through a code converting circuit 11. While an alarm information collecting circuit 5 transmits the alarm information ALD collected in the circuit 5 itself to an alarm information transmitting circuit 7 and at the same time outputs an alarm signal 5a to a state change detecting circuit 6. The circuit 6 outputs a control signal 6a after detecting a state change in response to the signal 5a and controls the circuit 7 so that the address information ALA and the alarm information ALD given from a self-station address memory circuit 8 are inserted into and outputted from the transmission frame.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention connects a central monitoring device and a plurality of terminal devices via a loop-shaped transmission path, and transmits data between each terminal device. The present invention relates to a loop data transmission device in which the central monitoring device monitors alarm information from each terminal device.

(Prior Art) FIG. 3 is a block diagram showing the main parts of a terminal device forming a conventional loop data transmission device, and FIG. 4 is a transmission format diagram used in the conventional example of FIG. 3.

As shown in FIG. 4, in addition to the data area 22 for inserting data into the transmission format, there is provided an alarm area 23 for inserting only alarm information. This warning area 23 is divided into n parts corresponding to the number n of a plurality of terminal devices, and is divided into n terminal warning areas 23a, 23b, . . . for each terminal device.
・23n is assigned.

In the terminal device shown in FIG. 3, the case where the alarm information collected by the alarm information collecting circuit 5 is transmitted from the alarm information transmitting circuit 7 will be explained first. Synchronization is achieved with @2, and the transmitting/receiving circuit 3 inserts the alarm information ALD2 transmitted from the alarm information transmitting circuit 7 into the area assigned to itself, for example, the terminal alarm area 23b, and transmits the code after being converted by the code converting circuit 11. Transmission via roads.

Therefore, the central monitoring device installed in the center specifies the address of the terminal device by decoding the contents of the alarm information ALD 2 inserted into the terminal alarm area 23b and determining the position of the terminal alarm area 23b. Ta.

(Problems to be Solved by the Invention) In the conventional loop data transmission device described above, it is necessary to prepare a terminal alarm area in which individual alarm information for each terminal device is inserted in the transmission frame. Although the proportion of bits for alarm information increases, the proportion of bits for data decreases in comparison, resulting in a disadvantage that the efficiency of data transmission, which is the original purpose, decreases.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a loop-type data transmission device that efficiently transmits data by increasing the proportion of data bits.

(Means for Solving the Problems) In order to solve the above-mentioned problems and achieve the above objects, the present invention provides means for connecting a central monitoring device and each of a plurality of terminal devices with a loop-shaped transmission path. Each terminal device is a loop data transmission device that inserts and transmits its own transmission information on a predetermined transmission format including at least a data area and an alarm information area, and an alarm information collection circuit that collects alarm information and outputs an alarm signal; a state change detection circuit that detects a change in state based on the alarm signal; an address storage circuit that stores its own address; Each of the terminal devices includes an alarm information transmitting circuit that inserts the own address and alarm information into the upper layer information area of the transmission format and transmits the same only when the detection circuit detects a change in state. .

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of a terminal device constituting a loop-type transmission device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing one frame used in the embodiment of FIG. FIG. 3 is a diagram showing a transmission format for one frame. Frame-by-frame information received from the transmission path is converted to a logic level by a code conversion circuit 1 and sent to a transmitting/receiving circuit 3 via a synchronizing circuit 2. Data is transmitted and received with a data transmitting/receiving device (not shown) through an interface circuit 4. The transmission frame assembled by the transmission/reception circuit 3 is sent to the transmission #IL through the code conversion circuit 11.

On the other hand, the alarm information collection circuit 5 sends the alarm information ALD collected within its own device to the alarm information transmission circuit 7, and also outputs the alarm signal 5a to the state change detection circuit 6. When the state change detection circuit 6 detects a change in state in response to the alarm signal 5a, it outputs a control signal 6ae to the alarm information transmitting circuit 7, and outputs the address information ALA and alarm information AL from the local address storage circuit 8.
The alarm information transmitting circuit 7 is controlled so as to insert and output D into the above-mentioned transmission frame.

Next, the case where information is inserted and transmitted on the transmission formant shown in FIG. 2 will be explained.

Only when the state change detection circuit 6 detects a change in state, the alarm information ALD and the address ALA of its own station are inserted into the information area 23 shown in FIG. 2 and transmitted. Of course, data from a data transmitting/receiving device (not shown) is inserted into the data area 22.

21 is an area for inserting a start code, and 24 is an area for inserting a check code.

Therefore, the central monitoring device installed in the center decodes the address ALA of the information area 23 and the alarm information ALD to determine the content of the alarm information ALD and the address of the terminal device that transmitted the alarm information ALD.

As is clear from a comparison with FIG. 4, the data transmission efficiency is improved by increasing the occupancy rate of the data area 22 in the entire transmission format.

(Effects of the Invention) As explained above, according to the present invention, instead of allocating an information area for each terminal device to insert the alarm information of each terminal device, the information area is shared and the alarm information in each terminal device is By sending alarm information only when the state changes, the occupancy rate of the information area is reduced, and conversely, the occupancy rate of the data area is increased, resulting in efficient data transmission.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main part of a terminal device of a loop-type transmission device showing an embodiment of the present invention, and FIG. 2 shows a transmission format for one frame used in the embodiment of FIG. 3 is a block configuration diagram of the main part of the terminal device of a conventional loop type transmission device, and FIG. 4 shows the transmission format for one frame used in the loop type transmission device of FIG. 3. FIG. 1.11... code conversion circuit, 2... synchronization circuit, 3.
... Transmission/reception circuit, 4... Interface circuit, 5...
- Alarm information collection circuit, 6... Status change detection circuit, 7...
Alarm information transmission circuit, 8... own station address storage circuit, S
...Synchronization signal, DATA...information section, ALA...
Alarm information address, ALD, ALD1~n-=alarm information, CHK... error check code.

Claims (1)

[Scope of Claims] A central monitoring device and a plurality of terminal devices are each connected via a loop-shaped transmission path, and each of the terminal devices transmits information on a predetermined transmission format including at least a data area and an alarm information area. A loop data transmission device that inserts and transmits its own transmission information includes an alarm information collection circuit that collects alarm information within the device and outputs an alarm signal, and a circuit that detects changes in status based on the alarm signal. a state change detection circuit for detecting a change in state, an address storage circuit for storing its own address, and inserting its own address and alarm information into the alarm information area on the transmission format only when the state change detection circuit detects a change in state. A loop-type data transmission device characterized in that each of the terminal devices is provided with an alarm information transmission circuit for transmitting alarm information.