JP2677231B2 - Loop bus exchange method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention finds application in local area networks (LANs) and elsewhere. The present invention relates to an improvement of a loop bus exchange system configured to selectively take out a required signal from a loop bus on which a time division signal is transmitted. The present invention relates to improvements for reducing the load on a central control unit.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a loop bus 1 through which a time division signal is transmitted and one or more branch nodes 2 provided in the loop bus are provided. The line circuit 11 connected in a line
The configuration is such that the n-channel data signal 4 and the k-channel control signal 5 are output as parallel signals. This branch node is provided with a switching circuit that branches and connects the time division signal transmitted to the loop bus 1 in synchronization with the time division signal. The switching timing of this branch node is controlled by the central controller 12 in synchronization with each line circuit 11. Devices having such a structure are disclosed in Japanese Patent Laid-Open Nos. 62-292040, 60-196042 and others.

Here, the central controller 12 is the loop bus 1
Assign the time slot of. One line circuit 12
When (for example, A) and another one of the line circuits 12 (for example, B) communicate with each other, an empty time slot in the loop bus 1 is searched for and assigned to the communication between AB.
In this way, the communication control is collectively controlled by the central controller 12.

[0004]

In such a system,
The burden on the central controller 12 is heavy. Therefore, a large-scale processing device is required as the central control device, and the system becomes expensive. Further, if the processing capacity of the central control unit is limited, it takes time for the connection processing.

The present invention has been made against such a background, and an object thereof is to reduce the load on the central control unit. It is an object of the present invention to reduce the cost of the system by downsizing the central controller. It is an object of the present invention to provide a loop bus switching system capable of executing a switching connection larger in scale than the conventional system even if the central control unit is small and inexpensive.

[0006]

The present invention comprises a loop bus (1) through which a time division signal is transmitted, and one or more branch nodes (2) provided on the loop bus. In 2), a parallel bus terminal (6) for outputting an n-channel data signal (4) and a k-channel control signal (5) as parallel signals, and the time division signal to the parallel bus terminal as the time division signal. In the loop bus exchange system including a switching circuit (3) connected in synchronization, a frame counter (7) for detecting frame information from a signal of the parallel bus terminal is provided in the branch node (2), and the switching is performed. The circuit (3) is characterized in that it includes circuit means for performing switching in accordance with the output information of the frame counter, independently of the central control unit involved in the switching connection of the loop bus.

Furthermore, the present invention provides the branch node (2)
And a switching circuit (3) provided with a detection circuit (8) for detecting time slot use information included in the control signal.
Can be configured to include circuit means for switching so as to select a time slot being used according to the output information of the detection circuit.

In this case, k is 2, one of the control channels is the time slot use information,
The other one is a signal indicating the frame head.

[0009]

With the configuration of the present invention, the branch node independently establishes frame synchronization, and according to the frame synchronization,
The data signal to be branched can be branched and the data signal to be coupled can be coupled to the loop bus. Therefore, the central control unit is relieved from controlling the switching circuit of the branch node, and the burden is reduced accordingly.

The data signal to be branched is detected by the time slot use information indicating whether or not the time division time slot is used, and branch connection is performed only in the used time slot, thereby performing the opposite communication. It is possible to set the route surely.

For this reason, it is convenient to use the time slot use information as information of an independent control channel.

If the time slot use information is configured to send out a logic "0" during communication, the structure is simplified because this information line is simply connected to ground during communication.

[0013]

1 is a block diagram of a branch node according to an embodiment of the present invention. FIG. 2 is an overall configuration diagram of the system according to the embodiment of the present invention. FIG. 3 is a time chart for explaining a signal transmitted to the bus according to the embodiment of the present invention.

As shown in FIG. 2, the entire configuration of the loop bus exchange system of the present invention is such that a loop bus 1 connected in a loop and transmitting a time division signal, and a plurality of branch nodes provided in this loop bus. 2, an n-channel data signal 4 and a k-channel control signal 5 are output as parallel signals to the branch node 2, and a large number of line circuits 11 are connected to the parallel signals. The line circuit 11 is controlled by the central controller 12.

The feature of the present invention resides in the branch node 2 shown in FIG. That is, the branch node 2 of the present invention has n
Channel data signal 4 and k channel control signal 5
Is provided as a parallel signal, and a switching circuit 3 for connecting the time division signal to the parallel bus terminal in synchronization with the time division signal is provided to the branch node 2 from the signal of the parallel bus terminal 6. A frame counter 7 for detecting frame information is provided, and the switching circuit 3 is provided with a circuit means for performing switching in accordance with the output information of the frame counter and a control signal independently of the central control unit involved in the switching connection of the loop bus. And a detection circuit 8 for detecting included time slot usage information. And
The k is 2, one of the control channels is the time slot use information, and the other is a signal indicating a frame head.

In the apparatus having such a configuration, as shown in FIG. 3, the frame counter 7 is reset by a signal indicating the frame head, and thereafter, counting is performed for each frame. That is, from time slot 0 to 10 per time slot
Identify up to number 23. Then, in the line circuit 11, the time slot use information is set to the value “0” during communication in the assigned time slot, and set to “1” at the end of communication. The detection circuit 8 detects this change point and, when the time slot use information is "0", sends the corresponding data signal on the loop, and when the time slot use information changes to "1", from the next frame. The change is sent on the loop. Based on this information, each switching circuit 3 can know the time slot use information on the loop. The same applies when branching the data signal from the loop bus 1,
When the time slot use information is set to the value “0” in the assigned time slot, the data signal of the time slot is branched into the data signal 4 to enable communication.

By this operation, the central control unit 12 does not interfere with the operation of the switching circuit 3 and the switching circuit 12 operates autonomously. This reduces the burden on the central controller 12.

[0018]

As described above, according to the present invention, the central control unit does not have to intervene in the loop bus switching circuit, the load on the central control unit is reduced, and the central control unit is inexpensively constructed. You can Further, since the central controller can be exchanged on a large scale with a small and inexpensive central controller, the system can be constructed at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a branch node according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment system of the present invention.

FIG. 3 is a time chart for explaining the operation of the system of the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional example method.

[Sign]

 1 Loop Bus 2 Branch Node 3 Switching Circuit 4 Data Signal (n Channel) 5 Control Signal (k Channel) 6 Parallel Bus Terminal 7 Frame Counter 8 Detection Circuit 11 Line Circuit 12 Central Control Unit

Claims (3)

(57) [Claims] 1. A loop bus (1) for transmitting a time-division signal, and one or more branch nodes (2) provided on the loop bus, wherein the branch node (2) has n channels. A parallel bus terminal (6) that outputs a data signal (4) and a control signal (5) of the k channel as a parallel signal, and a switching circuit that connects the time division signal to the parallel bus terminal in synchronization with the time division signal ( 3) in a loop bus exchange system comprising: a signal from the parallel bus terminal to the branch node (2);
The signal indicating the frame head is detected and the tie is
A frame counter (7) for counting the number of slots ,
Detects time slot usage information included in the control signal
A detection circuit (8) is provided, and the switching circuit (3) is used according to a time slot count value output from the frame counter, independently of a central control device involved in the switching connection of the loop bus.
A loop bus exchange system characterized by including circuit means for performing switching so as to select an available time slot . Wherein said k is 2, one of the control channels are the time slot usage information, the other one of the claims 1 Symbol placement loop bus switching system is a signal indicating the frame head . 3. The loop bus exchange system according to claim 2, wherein the time slot use information is a logic "0" during communication and a logic "1" is transmitted except during communication.