JPH0756987B2 - Loop network bypass method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a loop network bypass system, and more particularly to a loop network bypass system in which two loop networks having different transmission rates are combined.

[Prior Art] In recent years, with the development of the information society, by connecting different types of networks, a more comprehensive network system is often formed. For example, the fourth
The figure shows a case where two loop networks are combined to form one loop network. In FIG. 4, both the loop network 50 and the loop network 51 are configured such that a transmission frame of a fixed length circulates on the loop. The loop network 50 has a higher transmission speed than the loop network 51. In FIG. 4, reference numeral 52 is a node to which a terminal device 53 is connected.
Hereinafter, for convenience of explanation, the loop network 50 will be described as a high-speed network, and the loop network 51 will be described as a low-speed network.

FIG. 5 shows a frame structure of the high speed network. Reference numeral 62 is a frame header of the high speed network. The high speed network uniquely allocates the partial area 61 of the transmission frame 60 for the low speed network in order to incorporate the low speed network into itself. Then, in the low-speed network, its own transmission frame is placed in this area 61, and the actual transmission is left to the high-speed network for transmission on the loop.

By the way, a transmission frame 60 having a constant length as shown in FIG.
In a loop network configured to circulate on a loop, transmission between the terminal devices 53 is not performed by software processing by a central processing unit (abbreviated as "MPU") (not shown) provided in the node 52, and Processing was done by hardware. However, it is general that the terminal device 53 determines where in the transmission frame 60 to access based on the initialization command from the MPU. Also, even if there is no abnormality in the hardware part, if there is something wrong with the MPU itself and the software runs out of control, there is a possibility that the access setting in the transmission frame 60 will be set to an incorrect value. However, normal data transmission cannot be performed in the entire system.

Therefore, in such a loop network, each terminal device
Not only the transmission between 53, but also the MPUs of each node 52 communicate with each other to constantly monitor whether or not an abnormality has occurred in the MPU. Then, as shown in FIG. 6, by performing a loopback operation, the node 70a and the loop indicated by the dotted line are separated, and the network is reconfigured by the loop indicated by the solid line connecting the nodes 70b to 70d, and the entire system is constructed. Guarantees normal transmission.

[Problems to be Solved by the Invention] However, in such a loop network, loopback control can be performed only in a high-speed network that actually transmits data on the loop transmission line, and in a low-speed network, loopback control can be performed. Can't do.

In addition, since this low-speed network is a low-speed network in which a transmission line as shown in FIG. 7 is apparently formed,
Each node 80 of the low-speed network once takes in all the frames of the low-speed network, rewrites necessary data, and then transmits the low-speed network frame to the next-stage node. Here, for example, if an abnormality occurs in the MPU of a node with a low-speed network, abnormal data may be transmitted from the node with the abnormality at this time, and it is necessary to disconnect the node with the abnormality from the system. . However, on the low-speed network side, the MP of a node
Even if it detects that an error has occurred in U, it cannot perform the loopback control operation and disconnect that node. Therefore, in the above loop network, the transmission of the entire low speed network may be abnormal due to the abnormality of the MPU of one node.

Therefore, the object of the present invention is made in view of the above situation, and when there is no abnormality in the MPU in one low speed network node, it is detected that there is a signal change for a predetermined time or longer, and the node of the low speed network node is detected. Is not disconnected from the system, and when an error occurs in the MPU in one low-speed network node, it detects that no signal is sent for a predetermined time or longer, disconnects the low-speed network node from the system, and The purpose of the present invention is to provide a bypass method for a loop network that enables normal operation of the entire network.

[Means for Solving the Problems] As means for solving the above problems, the present invention provides a configuration in which a transmission frame of a fixed length circulates on a loop in both the first loop network and the second loop network. And the first loop network has a higher transmission speed than the second loop network,
The first loop network uniquely allocates a part of its own transmission frame for the transmission of the second loop network, and the second loop network puts its own transmission frame on the allocated area and Transmission is carried out over the loop by the first loop network, in which each node of the first loop network constantly monitors the signal sent from the central processing unit of the node of the second loop network, When it is detected that no signal has arrived for a certain period of time, the node of the second loop network is set to the bypass state, and
The signal sent from the central processing unit is constantly monitored, and when a signal change is detected for a predetermined time or longer, the node of the second loop network is placed in the anti-bypass state.

[Operation] Each node of the high speed network constantly monitors the signal transmitted from the central processing unit (MPU) of the node of the low speed network. When it is detected that the MPU of the low-speed network is abnormal and no signal is received for a predetermined time or longer, the node of the low-speed network is set to the bypass state and the low-speed network node is disconnected to prevent the entire network from going down.

Further, when a signal change is detected for a predetermined time or more, the node of the low speed network is placed in the anti-bypass state and the low speed network node is not disconnected, thereby compensating the smooth operation of the network.

From these things, a reliable communication network is provided.

[Embodiment] Next, an embodiment of the present bypass system will be described. FIG. 1 is a schematic configuration diagram showing an embodiment of a bypass device to which the present system is applied. In FIG. 1, reference numeral 1 is a node of a high speed network, which is connected between a node 1 of this high speed network and a node 2 of a low speed network. The output signal transmission line 101 for transmitting the output signal of the node 2 of the low speed network is connected, and the data transmission / reception line 100a for transmitting / receiving data is connected to the data transmission / reception line 100 and the bypass control circuit 5 described later. .

A central processing unit (hereinafter abbreviated as “MPU”) 3 that controls the control center of this device is provided in the node 2 of the low-speed network, and the node 1 of the high-speed network is controlled by the control signal from the MPU 3. It is configured to operate the MPU monitoring circuit 4 provided therein. Further, a bypass control circuit 5 which operates by a monitoring signal from the MPU monitoring circuit 4 is provided in the node 1 of the high speed network, and the data from the preceding node is transmitted to the next node as it is, or the low speed network is operated. It is configured so that it is possible to select whether to send the data sent from the node to the next stage node.

The bypass device will be described in detail. The MPU 3 of the low-speed network node 2 uses the MPU output signal transmission line 101 to send a signal to the MPU monitoring circuit 4 that is turned on at regular intervals by software control.

FIG. 2 is a diagram showing an output signal control system of the bypass device. FIG. 2 (a) shows that the MPU 3 is normal and the MPU monitoring circuit 4
2B shows the case where there is a signal change in the signal sent to the MPU 3, and FIG. 2B shows the case where there is no signal change in the signal sent to the MPU monitoring circuit 4 because the MPU 3 is abnormal.

On the high-speed network side mentioned above, M which monitors the MPU output signal
When the data of the PU monitoring circuit 4 and the low speed network is transmitted to the next stage node, the bypass control circuit 5 transmits the data transmitted from the low speed network node 2 (normal mode).
Or to send the data from the preceding node as it is (bypass mode).

The MPU monitoring circuit 4 constantly monitors the output signal from the MPU 3, detects that the signal has stopped changing for a certain period of time, and controls the bypass control circuit 5 to enter the bypass mode. For example, in the low speed network node 2
When the MPU3 is normal, an output signal is output from the MPU3 to the MPU monitoring circuit 4 (there is a signal change). At this time, the MPU monitoring circuit 4 of the high-speed network detects that the MPU is normal and switches the bypass control circuit 5 from the bypass mode B to the normal mode A, so that the data passes from the preceding node to the data transmission / reception line 100a. And transmits to the next stage node through the low speed network node 2.

Further, when an abnormality occurs in the MPU3 of the low speed network node 2 and the output signal is not output from the MPU3 to the MPU monitoring circuit 4 (the signal change disappears), the MPU monitoring circuit 4 of the high speed network detects the abnormality. By detecting and switching the bypass control circuit 5 from the normal mode A to the bypass mode B, data is transmitted from the preceding node to the succeeding node without passing through the low speed network node 2. FIG. 3 shows the state of the transmission line in this case. As is clear from this figure, the low-speed network node 2 in which the abnormality has occurred is disconnected, and the high-speed network node 1 performs normal transmission.

In this bypass device,
Even when an MPU malfunctions, it detects that no signal is sent for a certain period of time and operates to disconnect the low-speed network node, ensuring normal operation of the network as a whole, resulting in reliability. Highly reliable system can be provided.

As described above, according to the present invention, when the central processing unit (MPU) in the low speed network node is operating normally and a signal change is detected for a predetermined time or more, the low speed network node is not disconnected. When the MPU in a certain low-speed network node operates abnormally, it detects that no signal is sent for a certain period of time, and operates to disconnect the low-speed network node to make the entire network normal. The operation is guaranteed, and as a result, a highly reliable system can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a bypass device to which the system of the present invention is applied, FIG. 2 is a diagram showing an output signal control system of the bypass device, and FIG. 3 is a low-speed network when an MPU is abnormal. FIGS. 4 to 7 are diagrams showing a transmission order, and are diagrams showing a conventional loop network. In the figure, 1 is a high speed network node, 2 is a low speed network node, 3 is an MPU (central processing unit), 4 is an MPU monitoring device, and 5 is a bypass control device.

Claims (2)

[Claims] 1. The first loop network and the second loop network both have a configuration in which a transmission frame of a fixed length circulates on the loop, and the first loop network transmits from the second loop network. The high speed network, the first loop network uniquely allocates a part of the area of its own transmission frame for the transmission of the second loop network, and the second loop network allocates its own area to the allocated area. In the loop network in which the transmission frame is carried and the actual transmission is performed on the loop by the first loop network, each node of the first loop network is sent from the central processing unit of the node of the second loop network. When the signal is constantly monitored and it is detected that the signal does not come for a certain period of time, the second Bypass scheme loop network, which comprises a node-loop network to the bypass state. 2. The first loop network and the second loop network both have a configuration in which a transmission frame of a fixed length circulates on the loop, and the first loop network transmits from the second loop network. The high speed network, the first loop network uniquely allocates a part of the area of its own transmission frame for the transmission of the second loop network, and the second loop network allocates its own area to the allocated area. In the loop network in which the transmission frame is carried and the actual transmission is performed on the loop by the first loop network, each node of the first loop network is sent from the central processing unit of the node of the second loop network. The signal is constantly monitored, and if a signal change is detected for a predetermined time or longer, the second loop net Bypass scheme loop network, which comprises a node over click counter-bypassed.