JPH0916520A - Data processing system and data transfer method - Google Patents

Abstract

PURPOSE: To keep a connectable state between each computer and terminal equipment by providing a switching means which switches the connection of one of data processors with an input/output device corresponding to an instruction from the outside. CONSTITUTION: When ID data in accordance with the equipment code of the terminal equipment 2 that is a connection target is set by a switch circuit 7 for data setting in a switching device 4, a CPU 6 fetches the ID data in reponse processing. Thence, either the computer 1A or 1B is connected to the terminal equipment 2 by operating a manual switch SW. For example, it is assumed that an on-line state in which the computer 1A is connected to the terminal equipment 2 is set, and the computer 1A transmits the instruction in accordance with the transmission request of the ID data to the switching device 4. The CPU 6 fetches the ID data that is response data in the switch circuit 7 for data setting, and transmits it to the computer 1A. At such a case, the computer 1A confirms the connection of the terminal equipment 2. The computer 1A executes every kind of data transfer between connected terminal equipment 2 by a switch circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing system having a switching device for switching connection between a plurality of computers and a common terminal device.

[0002]

2. Description of the Related Art Conventionally, there is a data processing system capable of switching connection with a plurality of computers and inputting / outputting data to / from each computer by a shared terminal device. As shown in FIG. 6, this system includes a plurality of (for convenience, two) computers 1A, 1 which are, for example, UNIX type workstations.
B, shared terminal device 2 and switching device 3.

The terminal device 2 is a data input / output device having, for example, a keyboard and a display device. The switching device 3 is normally a device for connecting either the computer 1A or 1B to the terminal device 2 by a switching operation of the manual switch SW.

Assuming that the switching device 3 connects the computer 1A to the terminal device 2 and puts it in the online state by the manual switch SW, the computer 1A transfers input / output data with the terminal device 2. For example, when the computer 1A requests ID data which is the device code of the terminal device 2,
The terminal device 2 switches the ID data to the switching device 3 in response to the request.
Via computer to computer 1A.

On the other hand, the computer 1B is not connected to the terminal device 2 (offline state). Therefore, the computer 1B cannot transfer data with the terminal device 2 until the connection switching by the switching device 3 is executed.

[0006]

Conventionally, in a system of a system in which a connection between a plurality of computers 1A and 1B and a shared terminal device 2 is switched by a switching device 3, computers 1B other than the online computer 1A are in an offline state. Data transfer with the terminal device 2 is disabled. Therefore, even if the computer 1B in the offline state outputs a command requesting ID data, the response data (ID data) is sent from the terminal device 2.
Will not be answered.

In such a state where there is no response, the computer 1
B determines that the terminal device 2 is in the unconnected state.
Therefore, even if the connection is switched by the switching device 3, the computer 1B may stop data transfer between the terminal devices 2.

An object of the present invention is to maintain a connectable state between each computer and a terminal device by executing a necessary response process even for an instruction from a computer in a non-connected state among a plurality of computers. It is to provide a data processing system capable of processing.

[0009]

According to a first aspect of the present invention, there is provided a data processing system having a plurality of data processing devices for independently performing data processing and a common input / output device for each data processing device, It is a system having switching means for switching the connection between any one of the data processing devices and the input / output device in response to an instruction. The switching means has means for transmitting response data in response to a request from the data processing device that is not connected to the input / output device.

A second aspect of the present invention is a data processing system having a plurality of data processing devices for independently performing data processing and a common input / output device for each data processing device, wherein each data is processed in response to an instruction from the outside. A system having switching means for switching connection between any one of the processing devices and the input / output device and setting means for setting response data according to a specific request of each data processing device.

A third aspect of the present invention is a data processing system having a plurality of data processing devices for independently executing data processing and a common input / output device for each data processing device, wherein each data is processed according to an instruction from the outside. A system having switching means for switching the connection between any one of the processing devices and the input / output device and memory means for storing response data output from the input / output device in response to any specific request of each data processing device.

[0012]

In the first aspect of the present invention, the switching means switches the connection between any one of the data processing devices and the input / output device by, for example, a manual switch operation. The switching means transmits the response data in response to an instruction from each data processing device. As a result, even when an instruction is output from the data processing device that is not connected to the input / output device, necessary response data is transmitted to the data processing device. Therefore, the data processing device side can always recognize that it can be connected to the input / output device.

According to a second aspect of the present invention, the switching means performs connection switching between any one of the data processing devices and the input / output device, and the response data set by the setting means in response to a command from each data processing device. To send.

In the third aspect of the present invention, the switching means performs connection switching between any one of the data processing devices and the input / output device, and the response data stored in the memory means in response to a specific request from each data processing device. To send.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of a data processing system according to the first embodiment, FIG. 2 is a flow chart for explaining the operation of the same embodiment, and FIG. 3 is a data processing system according to the second embodiment. 4 is a block diagram showing an essential part, FIG. 4 is a flowchart for explaining the operation of the embodiment, and FIG. 5 is a block diagram showing an essential part of a data processing system according to the third embodiment. (Structure of First Embodiment) As shown in FIG. 1, this system comprises a plurality (two for convenience) of computers 1A and 1B, a terminal device 2 and a switching device 4. Each computer 1A, 1B
Is, for example, a UNIX type workstation, and executes data processing independently of each other. The terminal device 2 is
For example, it is a data input / output device including a keyboard and a display device, and transfers input / output data to / from each of the computers 1A and 1B.

The switching device 4 is a characteristic element of the present invention and has a switching circuit 5, a control circuit (CPU) 6 and a data setting switch circuit 7. The switching circuit 5 is a circuit that normally switches the connection between one of the computers 1A and 1B and the terminal device 2 by the switching operation of the manual switch SW. The switching circuit 5 is a manual switch S
Instead of W, a circuit operated by an external switching control signal from another computer may be used.

The CPU 6 is a microprocessor which controls data transfer between any one of the computers 1A and 1B connected by the switching circuit 5 and the terminal device 2. further,
The CPU 6 executes a response process of transmitting the response data set by the data setting switch circuit 7 to the computers 1A and 1B.

The data setting switch circuit 7 is a so-called dip switch, has a number of slide switches corresponding to the number of bits, and is a circuit for externally setting data having the number of bits. In this embodiment, it functions as a switch circuit for setting ID data corresponding to the device code of the terminal device 2. (Operation of the First Embodiment) Next, the operation of the first embodiment will be described with reference to the flowchart of FIG.

First, in the switching device 4, when the ID data corresponding to the device code of the terminal device 2 to be connected is preset by the data setting switch circuit 7, the CPU 6 takes in the ID data during the response process (step S1). .
Next, by operating the manual switch SW, the computer 1
Either A or 1B is connected to the terminal device 2 (step S2). That is, of the computers 1A and 1B, one required for data processing is brought online and the other is brought offline.

Here, it is assumed that the computer 1A is in the online state for connecting to the terminal device 2 and the computer 1B is in the offline state. It is assumed that the computer 1A in the online state has transmitted a command corresponding to the ID data transmission request (specific request) to the switching device 4 in order to confirm the connection state of the terminal device 2 (step S3).

The CPU 6 decodes the content of the instruction from the computer 1A, fetches the ID data which is the response data by the data setting switch circuit 7 in response to the request, and sends it to the computer 1A (YES in step S4, S5). ). From the response of this ID data, the computer 1A confirms that the corresponding terminal device 2 is connected. Computer 1A
Between the terminal device 2 connected by the switching circuit 5,
Various types of data transfer (transmission / reception) necessary for data processing are executed (step S6).

On the other hand, it is assumed that the computer 1B in the off-line state also transmits a command corresponding to the ID data transmission request to the switching device 4 in order to confirm the connection state of the terminal device 2 (step S3). As in the case of the computer 1A, the CPU 6 decodes the content of the instruction from the computer 1B, fetches the ID data which is the response data by the data setting switch circuit 7 in response to the request, and sends it to the computer 1B (step S4). No, S7).

In this way, the computer 1B can receive the response data corresponding to the request from the switching device 4 by transmitting the command corresponding to the request for transmitting the ID data. Therefore, even if the terminal device 2 is not connected due to the switching operation of the switching device 4, the computer 1B
By the response process of the switching device 4, the connectable state of the terminal device 2 can be confirmed. As a result, computer 1B
Can reliably perform data transfer with the terminal device 2 when the connection state with the terminal device 2 is established by the switching operation of the switching device 4. (Second Embodiment) Next, as shown in FIG. 3, a system according to a second embodiment of the present invention comprises a plurality of computers 1A and 1A.
B, a terminal device 2 and a switching device 4 having a memory 8. The memory 8 has an area 8a for storing commands transmitted from the computers 1A and 1B and an area 8b for storing ID data transmitted from the terminal device 2. Since the other structure is similar to that of the first embodiment, the same reference numerals are given and the description thereof is omitted.

The operation of the embodiment will be described with reference to the flowchart of FIG. First, by operating the manual switch SW, either the computer 1A or 1B and the terminal device 2
And are connected (step S10). That is, computer 1
One of A and 1B required for data processing is brought into an online state and the other is brought into an offline state. Here, the computer 1A is brought into an online state in which it is connected to the terminal device 2,
It is assumed that the computer 1B is offline.

It is assumed that the computer 1A in the online state has transmitted a command corresponding to the ID data transmission request to the switching device 4 in order to confirm the connection state of the terminal device 2 (step S11). The CPU 6 decodes the content of the instruction from the computer 1A and determines whether to execute the response process.

When the CPU 6 confirms the execution of the response process,
By referring to the memory 8, it is searched whether or not ID data (response data) corresponding to the command is stored (step S1).
2). If there is no ID data in the memory 8,
The CPU 6 receives the ID data from the terminal device 2 and sends it to the computer 1A (NO in step S13, Y in step S14).
ES, S15).

At this time, the CPU 6 saves the command data received from the computer 1A and the ID data received from the terminal device 2 in the memory 8 (step S16). Computer 1A
Confirms that the terminal device 2 is connected by the response of the ID data, and executes various data transfer (transmission / reception) necessary for data processing with the connected terminal device 2 (step S19). .

Next, it is assumed that the computer 1B in the off-line state also transmits a command corresponding to the ID data transmission request to the switching device 4 in order to confirm the connection state of the terminal device 2 (step S11). As in the case of the computer 1A, the CPU 6 decodes the content of the instruction from the computer 1B and determines whether to execute the response process.

When the CPU 6 confirms the execution of the response process,
By referring to the memory 8, it is searched whether or not ID data (response data) corresponding to the command is stored (step S1).
2). Here, the ID data is stored in the memory by the processing of the computer 1A (YE in step S13).
S). The CPU 6 reads the ID data from the memory 8,
The data is transmitted to the computer 1B (step S17).

In this way, the computer 1B can receive the response data corresponding to the request from the switching device 4 by transmitting the command corresponding to the request for transmitting the ID data. Therefore, even if the terminal device 2 is not connected due to the switching operation of the switching device 4, the computer 1B
By the response process of the switching device 4, the connectable state of the terminal device 2 can be confirmed.

Before the computer 1A in the online state sends a command, the computer 1B in the offline state sends an ID.
When the command corresponding to the data transmission request is transmitted,
The CPU 6 cannot transmit the ID data (step S11)
~ NO in S14). That is, in the initial stage, the memory 8 has I
D data is not saved. Moreover, since the computer 1B is not connected to the terminal device 2, the I
Neither D data is transmitted. In such cases, the CPU
6 executes a processing routine prepared in advance to execute processing for transmitting data indicating that the terminal device 2 can be connected instead of the ID data (step S20). (Third Embodiment) Next, a system according to a third embodiment of the present invention will be described with reference to FIG.
B, terminal device 2, switching device 4 and monitoring devices 9A, 9B
Consists of In this embodiment, monitoring devices 9A and 9B corresponding to the computers 1A and 1B are provided. The monitoring devices 9A and 9B are composed of computers 1A and 1B and a switching device 4
It has a microprocessor that monitors data transfer between them and executes response processing in response to a request to transmit ID data. The switching device 4 may have the same configuration as that shown in FIG. 1 or FIG. Further, the other structure is the same as that of the first or second embodiment, and the description thereof will be omitted.

In this embodiment, the monitoring devices 9A and 9B start the monitoring operation when power is supplied from the computers 1A and 1B through the power supply lines 10A and 10B. That is, the monitoring devices 9A and 9B perform a response process of transmitting the ID data stored in advance to the computers 1A and 1B when the command corresponding to the ID data transmission request is transmitted from the computers 1A and 1B. As a result, the computers 1A and 1B can confirm that the terminal device 2 is in the connectable state by receiving the ID data.

In the system of this embodiment, the computers 1A, 1
Since the monitoring devices 9A and 9B are provided corresponding to the respective Bs, the computers 1A and 1B can confirm the connection state of the terminal device 2 in either the online state or the offline state by the switching device 4. . In particular, in the second embodiment, when a command is transmitted from the computer 1B in the offline state before the ID data is stored in the memory 8 of the switching device 4, the CPU 6 needs to perform a specific response process. (Step S20). On the other hand, in the third embodiment, for the computer 1B in the offline state, the corresponding monitoring device 9B can always perform the response process.

[0034]

As described above in detail, according to the present invention, in a system in which a connection between a plurality of computers and a common terminal device is switched by a switching device, the computers in the unconnected state can be connected to the I
Even when a request such as a D data transmission request occurs, a response process according to the request can be executed. Therefore, when the terminal device is in the unconnected state, it is possible to prevent a situation in which the computer side erroneously determines, and to maintain the connectable state between the computer and the terminal device. As a result, data transfer between the computer and the terminal device can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a data processing system according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment.

FIG. 3 is a block diagram showing a main part of a data processing system according to a second embodiment.

FIG. 4 is a flowchart for explaining the operation of the second embodiment.

FIG. 5 is a block diagram showing a main part of a data processing system according to a third embodiment.

FIG. 6 is a block diagram showing a main part of a conventional data processing system.

[Explanation of symbols]

1A, 1B ... Computer, 2 ... Terminal device, 3, 4 ... Switching device, 5 ... Switching circuit, 6 ... Control circuit (CPU), 7 ... Data setting switch circuit, 8 ... Memory, 9A, 9B ... Monitoring device.

Claims (6)

[Claims] 1. A plurality of data processing devices for independently performing data processing, an input / output device for inputting / outputting data to / from the data processing device selected from the respective data processing devices, and an external instruction. And a switching means for switching the connection between any one of the data processing devices and the input / output device according to the request and transmitting response data in response to a request from the data processing device that is not connected to the input / output device. A data processing system characterized by the above. 2. A plurality of data processing devices for independently performing data processing, an input / output device for inputting / outputting data to / from the data processing device selected from the respective data processing devices, and an external instruction. A switching means for switching the connection between any one of the data processing devices and the input / output device in response to the response data in response to a request from the data processing device in the connection state or the non-connection state with the input / output device. A data processing system comprising: 3. A plurality of data processing devices for independently performing data processing, an input / output device for inputting / outputting data to / from the data processing device selected from the respective data processing devices, and each of the data processing devices in advance. Setting means for setting response data according to a specific request of the device, and switching the connection between any one of the data processing devices and the input / output device in response to an instruction from the outside to establish a connection state with the input / output device or A data processing system, comprising: switching means for transmitting the response data set by the setting means in response to the specific request from the data processing device in a non-connected state. 4. A plurality of data processing devices for independently performing data processing, an input / output device for inputting / outputting data to / from the data processing device selected from each of the data processing devices, and each of the data processing devices. Memory means for storing response data output from the input / output device in response to any one of the specific requests, and switching of connection between any of the data processing devices and the input / output device according to an instruction from the outside. And a switching means for transmitting the response data stored in the memory means in response to the specific request from the data processing device connected or disconnected to the input / output device. Data processing system. 5. A plurality of data processing devices, an input / output device for inputting / outputting data to / from the selected data processing device, and one of the data processing devices and the input / output device according to an instruction from the outside. In a data processing system including switching means for switching connection, in response to a specific request from the data processing device connected to the input / output device by the switching means, the response data output from the input / output device is converted into the data. Transmitting to the processing device and storing in the memory means, the response stored in the memory means when the specific request from the data processing device connected or disconnected from the input / output device occurs Transmitting the data to the data processing device. 6. A plurality of data processing devices for independently performing data processing, an input / output device for inputting / outputting data to / from the data processing device selected from the respective data processing devices, and an external instruction. Switching means for switching the connection between any one of the data processing devices and the input / output device in response to the data transfer between the data processing device and the switching device, and a connection state or a non-connection state with the input / output device. When a specific request from the data processing device in the state is generated, a monitoring unit that outputs response data to be output from the input / output device to the data processing device in response to the specific request is provided. And data processing system.