JPS6285374A - Bus coupling device - Google Patents

Abstract

PURPOSE:To detach the own device from a common bus by the decision of a bus coupling device itself, by making the bus coupling device have a function for monitoring an access state to a connecting destination command bus. CONSTITUTION:A common bus 31 is connected to a bus 11 of the first system by bus coupling devices 15, 16, and it is in a state that the bus 31 cannot be brought to an access from a bus 21 of the second system. When the first system is using the bus 31 in this state, a CPU 12 is in a state that it can execute an access to a control part, etc. 32 of the bus 31 within a prescribed time interval. When it becomes unnecessary that an information processor 14 uses the bus 31, an access state monitoring circuit 17 decides that the device 14 does not require the bus 31, informs its result to the device 15 and detaches the bus 31 from the bus 11. In this state, the bus 31 can execute an access from an information processor 24, and by an instruction from a CPU 22, the bus 21 can be connected to the bus 31.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a bus coupling device for coupling information processing devices of a plurality of systems to a common bus.

``Prior Art'' When a conventional bus coupling device disconnects from a connected common bus, it receives a signal from a system stall monitoring device such as a watchdog timer or by a command from the central processing unit of the connected system. I was doing everything I could to receive it. With this method, under normal conditions, disconnection is impossible unless the central processing unit executes a disconnection command, and if the system stall detection device fails, automatic disconnection of all bus-connected devices becomes impossible in the event of a system stall. O This invention provides a bus coupling device that enables the bus coupling device to disconnect its own device from the common bus at its own discretion by providing the bus coupling device with a function of monitoring the access state to the common bus to which it is connected. Our goal is to provide the following.

"Means for Solving the Problem" According to the present invention, a common bus is used in a bus coupling device that couples two or more systems of information processing devices and a common bus that can be commonly used by those information processing devices. An access state monitoring circuit for monitoring the access state from the information processing device connected to the common bus to the devices connected to the common bus is provided in the bus coupling device, and based on the access state monitoring result of the access state monitoring circuit, the bus A means is provided for disconnecting the connected information processing device from the common bus at the discretion of the coupling device itself.

Embodiment Next, an embodiment of the bus coupling device according to the present invention will be described in detail with reference to the drawings.

The first system bus 11 has a central processing unit (CPU) 12,
A first system information processing device 14 to which a control unit etc. 13 is connected
is provided. Similarly, a second system information processing device 24 is provided to which a central processing unit (CPU) 22, a control section, etc. 23 are connected to the second system bus 21. bus 1
1 is connected to the common bus 31 via the bus coupling device 15.16, the bus 21 is connected to the common bus 31 via the bus coupling device 25.26, and the information processing device 14.24 selects the common bus 31. It is made available for use.

A control unit 32 is connected to the common bus 31.

In this embodiment, the bus coupling devices 15 and 25 are each provided with access state monitoring circuits 17 and 27 for monitoring the access state to the connected bus, and the access state monitoring circuits 17 and 27 are provided to monitor the access state to the connected bus, respectively, and the access state monitoring circuits 17 and 27 are provided to monitor the access state to the connected bus. destination bus) 31
When no command is executed to the control unit 32 connected to the bus coupling device 15.25, or when data transfer is not performed, the bus coupling device 15.25 disconnects itself from the common bus 31 to which it is connected.

For example, by bus coupling device 15.16 common bus 3
1 is connected to the first system bus 11, and the common bus 31 cannot be accessed from the second system bus 21. In this state, the common bus 31 is
When the system is in use, the central processing unit 1 of the first system
2, the common bus 310 control unit 32 within a certain time interval.
Make sure to access it. When the information processing device 14 of the first system no longer needs to use the common bus 31, the access state monitoring circuit 17 controls the information processing device 14 of the first system.
4 determines that the common bus 31 is unnecessary, notifies the bus coupling device 15 of the result, and the bus coupling device 15 disconnects the common bus 31 from the bus 11 of the first system. In this state, the common bus 31 can be accessed from the information processing device 24 of the second system, and the bus 21 can be connected to the common bus 31 by a command from the central processing unit 22 of the second system. .

The access state monitoring circuit 17 is composed of, for example, a counter circuit, and this counter circuit always counts up and executes some command from the first system central processing unit 12 to the control unit 32 of the common bus 31. or when a data transfer occurs.

Counter is reset. Central processing unit 1 of the first system
When there is no access from 2 and these signals no longer come, the count value of the counter circuit increases, and when this count value exceeds a preset value, the access status monitoring circuit 17 The information processing device 14 determines that the common bus 31 is unnecessary, notifies the bus coupling device 15 of the result, and disconnects the common bus 31.

The access state monitoring circuit 27 is similarly configured.

"Effects of the Invention" As explained above, the present invention provides a bus coupling device with a circuit that monitors the access state to a connected bus (common bus), thereby automatically eliminating the need for instructions from other devices. This has the effect that devices can be disconnected from the common bus and bus switching can be performed efficiently.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a bus coupling device according to the present invention. 11.21: Nogusu, 12, 22: Central processing unit, 13
．． 23.32: Control unit, etc., 14.24 + information processing device,
15. i6, 25, 26: bus coupling device, 17, 27:
Access status monitoring circuit, 31: common bus.

Claims (1)

[Claims] (1) In a bus coupling device that couples two or more systems of information processing devices and a common bus that can be commonly used by those information processing devices, information provided in the bus coupling device that uses the common bus. An access state monitoring circuit monitors the access state from the processing device to the device connected to the common bus, and the access state monitoring circuit monitors the access state, and the bus coupling device determines whether the device is connected or not. A bus coupling device comprising: means for disconnecting an information processing device from the common bus.