JPH06337821A - Common bus connection controller - Google Patents

Abstract

PURPOSE:To facilitate the segment/detachment of a device becoming an obstacle and to segment/detach and to reconnect after restoration the device becoming the obstacle without, stopping the use of a common bus or a whole system in a common bus connection system in an input/output interface to which plural input/output devices are connected. CONSTITUTION:A processor 12 in the input/output device 3 sets a signal line 71 to low, turns off a switch 21, and sets a signal line 70 to low turns off a switch 20 when a bus fault occurs and it is detached from the common bus. Then, its own bus is diagnosed. When it is abnormal, an error lamp is lighted, and a detached state is held. When it is normal, the signal line 70 is set to be high, the switch 20 is turned on, the signal line 71 is set to high, the switch 21 is turned on and the processor is connected to the common bus again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common bus connection control device in an input / output interface in which a plurality of input / output devices are connected to a common bus, and particularly to a common bus connection control in which a troubled device can be easily separated. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, SCSI (Small Com) has been used as an example of an interface for connecting a plurality of input / output devices to a common bus.
puter System Interface) bus is "ANSI standard
SCSI-2 X3T 9.2 / 86-109, pages 8 to 32 ". Here, an example of connection of input / output devices on the SCSI bus will be shown. In FIG. 2, 1 is a common bus, 2 is a common bus termination circuit, 3 is an input / output device,
4 is a host. In the SCSI bus, the common bus 1 is drawn into the input / output device 3, and the driver / receiver pair is connected to the common bus 1. In such a common bus system, when a failure that affects the common bus occurs in a certain device, it is difficult to isolate the failed device. The normal device will be disabled. In order to deal with the above-mentioned problem, as described in, for example, Japanese Patent Laid-Open No. 63-12055, each device is sequentially disconnected by a disconnection circuit and one disconnection control circuit provided in each device. The method of diagnosing is proposed.

[0003]

The above-mentioned prior art does not deal with an interface such as a SCSI bus in which the bus management units are dispersed in each device and there is no specific bus management unit. In the interface, since the common bus is pulled into the input / output device and the driver / receiver is paired and connected to the common bus, it is difficult to provide the disconnection control circuit centrally at one place. In addition, there is a problem that the common bus cannot be used during the bus diagnosis, and the use of the common bus or the entire system must be suspended when disconnecting the failed device or reconnecting it after repair. It was An object of the present invention is to provide a common bus connection control device capable of resolving such a problem and isolating only a failed device without disturbing the operation of other normal devices. is there. Another object of the present invention is to provide a common bus connection control device capable of connecting / disconnecting an input / output device even during operation of the common bus by gradually connecting / disconnecting the common bus to reduce electrical noise.

[0004]

In order to achieve the above object, a common bus connection control device of the present invention is a common bus system in which a plurality of input / output devices are connected. Means for connecting / disconnecting the signal line between the relay switch 21 and the relay switch driver 4 in FIG.
1, transistor 51, amplifier 61, etc.), and when a bus failure occurs, disconnect the device from the common bus to diagnose its own bus, hold the disconnected state if there is an error, and reconnect to the common bus if normal. It is characterized in that it is provided with a means for controlling the connection (function of the processing device 12). Also,
By its control means, when the power of the input / output device is turned on, it diagnoses its own bus, and if it is abnormal, it keeps the disconnected state,
It is characterized by controlling to reconnect to the common bus if normal. Further, in addition to the connecting / disconnecting means, means for connecting / disconnecting the signal line to / from the common bus having a resistor inserted in series with the input / output device (relay switch 20 of FIG. 1). , Damping resistor 30, relay switch driver 40, transistor 50, amplifier 60, etc.),
The connecting / disconnecting means is connected / disconnected in a stepwise manner to control to reduce electric noise (function of the processing device 12).

[0005]

According to the present invention, when a bus failure occurs, a self-diagnosis is performed by the connection / disconnection circuit and the bus diagnostic function for each input / output device, and as a result, only the device having the failure in its own circuit is transferred from the common bus. To be separated. Also, by connecting / disconnecting one or more connecting / disconnecting circuits in which a resistor is inserted in series with the input / output device, a rapid change in impedance is reduced, and as a result, Electrical noise is reduced. In this way, since each device connected to the common bus performs self-diagnosis, it is easy to isolate the device that has failed. In addition, since the failed device is automatically disconnected from the common bus, it does not interfere with the operation of other normal devices. Further, since the connection / disconnection with the common bus is performed stepwise to reduce the electric noise, the connection / disconnection of the input / output device is possible even during the operation of the common bus.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an input / output device in a common bus system according to an embodiment of the present invention. In FIG. 1, 1 is a common bus, 3 is an input / output device, 10 is a driver connected to the common bus 1, 11 is a receiver connected to the common bus 1, 12 is a processing device connected to the driver 10 and the receiver 11. (PROC), 20 and 21 are relay switches (SW ₁ and SW ₂ ), 30 is a damping resistor (RM), 4
Reference numerals 0 and 41 are relay switch driving units, 50 and 51 are transistors, and 60 and 61 are amplifiers (AMPs) for driving the transistors 50 and 51. In the common bus system of the present embodiment, the input / output device 3 is controlled by the processing device 12, and the connection between the common bus 1 and the driver 10 and the receiver 11 is such that the processing device 12 connects the signal lines 70 and 7.
This is performed by setting 1 to HIGH level. That is, when the signal lines 70 and 71 are set to the HIGH level, the transistors 50 and 51 are turned on and the relay switch drive unit 4
0 and 41 are driven to bring the relay switches 20 and 21 into the connected state. In addition to the function of controlling connection / disconnection between the common bus 1 and the input / output device 3, the processing device 12 has a bus diagnostic function by a diagnostic program.

FIG. 3 is a flow chart showing a common bus connection method according to an embodiment of the present invention, showing the processing of the processor 12 when the power of the input / output device 3 is turned on and when a bus failure occurs. is there. Immediately after the power is turned on, the signal line 7
Since 0 and 71 are LOW level, relay switch 20,
21 is in a separated state. The input / output device 3 first sets all the signal lines 80 to LOW (step 303),
The state of the signal line 81 is checked (step 304). As a result, if all the signal lines 81 are not LOW, it is determined that there is a failure in the device itself and the error lamp is turned on (step 30).
9), the relay switches 20 and 21 are kept in the separated state. If all the signal lines 81 are LOW (step 304), then all the signal lines 80 are set to HIGH (step 305), and the state of the signal line 81 is checked (step 306). As a result, if all of the signal lines 81 are not HIGH, it is determined that there is a fault in the device itself, the error lamp is turned on (step 309), and the relay switches 20 and 21 are left in the disconnected state. In addition, all the signal lines 81 are HIGH.
If so (step 306), the signal line 70 is set to HIGH to bring the relay switch 20 into the connected state (step 30).
7) The common bus 1 is connected to the driver 10 and the receiver 11 via the damping resistor 30. Next, when the relay drive time has elapsed, the signal line 71 is set to HIGH to bring the relay switch 21 into the connected state (step 308),
The common bus 1, the driver 10 and the receiver 11 are directly connected.

On the other hand, when the processing unit 12 detects a bus failure, first, the signal line 71 is set to LOW level to disconnect the relay switch 21 (step 301), and the common bus 1 and the driver are connected only via the damping resistor 30. 10 and the receiver 11 are connected. Next, when the relay drive time has elapsed, the signal line 70 is set to the LOW level to disconnect the relay switch 20 (step 302), and the connection between the common bus 1, the driver 10 and the receiver 11 is completely cut off. After that, the same as when turning on the power (Step 3
03-309), a bus diagnosis is performed, and if normal, reconnect to the common bus 1. In this embodiment, the relay switch is used for connection / disconnection with the common bus, but the effect does not change even if it is replaced with an electronic switch (for example, a MOS transistor).

[0009]

According to the present invention, the following effects (1) to (4) can be obtained. Since each device connected to the common bus performs self-diagnosis, (1) it is easy to isolate the device that has failed. (2) Since the failed device is automatically disconnected from the common bus, it does not interfere with the operation of other normal devices. (3) It can also be applied to an interface in which bus management units are distributed inside each device. Further, since the connection / disconnection with the common bus is performed stepwise to reduce the electric noise, (4) the input / output device can be connected / disconnected even while the common bus is operating.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an input / output device in a common bus system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional common bus connection system.

FIG. 3 is a flowchart showing a common bus connection method according to an embodiment of the present invention.

[Explanation of symbols]

 1 common bus 2 termination circuit 3 input / output device 10 driver 11 receiver 12 processing device 20 relay switch 21 relay switch 30 damping resistor 40 relay switch drive unit 41 relay switch drive unit 50 transistor 51 transistor 60 amplifier 61 amplifier 70 signal line 71 signal line 80 signal lines 81 signal lines

Claims (3)

[Claims] 1. In a common bus system to which a plurality of input / output devices are connected, a means for connecting / disconnecting a signal line to / from the common bus is connected to each of the input / output devices, and when a bus failure occurs, It is provided with means for disconnecting the device from the common bus, diagnosing its own bus, holding the disconnected state if abnormal, and controlling to reconnect to the common bus if normal. Common bus connection control device. 2. In a common bus system to which a plurality of input / output devices are connected, a means for connecting / disconnecting a signal line to / from the common bus is connected to each of the input / output devices, and a power supply for the device itself is turned on. Sometimes, a common bus connection control device is provided with means for diagnosing its own bus, holding a disconnected state if abnormal, and controlling to reconnect to the common bus if normal. 3. A means for connecting / disconnecting a signal line to / from a common bus, which has a resistor inserted in series with the input / output device, and the connecting / disconnecting means are connected in stages. 3. The common bus connection control device according to claim 1 or 2, further comprising: means for controlling to disconnect.