JPH1155299A - Data communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide data communication equipment in which an encode and decode processing at the time of transmitting and receiving data can be executed by a communication adapter. SOLUTION: This is a data communication device used by a computer system having an SCSI(small computer system interface) bus 13, and this device is provided with a communication adapter 12 having an SCSI function as a target which is connected with an SCSI bus 13, and with a host computer 11 having an SCSI function as an initiator which is connected with the SCSI bus 13. The communication adapter 12 is provided with an encoder 21 for encoding transmission data and a decoder 22 for decoding received data. Thus, a load on a processing operation in the host computer 11 can be reduced, and the execution efficiency of another processing such as communication control can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication apparatus used in a computer system having a SCSI bus.

[0002]

2. Description of the Related Art Conventionally, there is a device having a communication function by connecting a communication adapter to a SCSI bus of a host computer. Here, SCSI (Small Computer System Inter
face) is ANSI (American National Standard Ins
titute). Due to its specifications,
Commands and data are transferred between an initiator that issues an instruction and a target that receives and executes the instruction.

In such a conventional apparatus using a SCSI bus and having a facsimile adapter or the like, the host computer and the communication adapter function as a SCSI initiator (command issuing side) and a target (command receiving side), respectively. (See Japanese Unexamined Patent Publication No.
38163). Therefore, in the data communication between the host computer and the communication adapter, bidirectional data communication has been realized by transmitting data in each case as the initiator transmitting data and the receiving side as the target.

Many of such personal computers and workstations used as host computers have only the function of the SCSI initiator, and such personal computers and workstations cannot be used as the host computer of the above-mentioned conventional apparatus. there were. Because, when the host computer has only the function of the initiator and the communication adapter has only the function of the target, the communication adapter as the target notifies the host computer as the initiator that data has arrived from the outside via the communication line. This is because it has a problem that it is difficult to notify the user, and therefore, even if the communication adapter wants to transmit data to the host computer, it cannot transmit the data by itself.

[0005] As a data communication device which has solved such a defect in the data communication system, there is, for example, one shown in FIGS. 6 and 7. FIG. 6 is a block diagram showing a schematic configuration of such a conventional data communication device. This conventional data communication apparatus includes a host computer 1 having a function as a SCSI initiator, a communication adapter having a function as a SCSI target, and an SC connecting the host computer 1 and the communication adapter.
And an SI bus 3. The communication adapter 2 is also connected to a communication line 4. FIG. 7 is a block diagram showing a configuration of a communication adapter 2 used in the above-mentioned conventional data communication device. In this figure, reference numeral 5 denotes a CPU that controls the entire operation of the communication adapter 2, and 6 denotes a CP.
A read-only memory (ROM) for storing a control program of U5, a communication control unit 7 connected to the communication line 4 for controlling communication, a SCSI control unit 8 for controlling data transmission on the SCSI bus 3, and a transmission / reception 9 This is a buffer memory for temporarily storing data. The communication line 4 through which the communication adapter 2 transmits and receives data to and from the outside includes a wired, wireless or IrDA (line using optical communication).

In the conventional data communication device having such a configuration, the following operation is performed between the host computer 1 and the communication adapter 2. FIG. 8 is a time sequence diagram for explaining the operation of the conventional data communication apparatus. In this data communication device, it is assumed that the communication adapter 2 first receives received data from outside (S1). The host computer 1 checks whether or not there is data received from outside in the communication adapter 2.
Confirm using a CSI command (S2). This confirmation operation is periodically executed. Communication adapter 2
Thereafter, an acknowledgment is made because there is currently received data (S3). Then, since the host computer 1 knows from the communication adapter 2 that there is data received from outside in the communication adapter 2, the host computer 1 executes a data length request SCSI command for checking the data length of the received data (S4). ). In response, the communication adapter 2 sends the received data length data (S5). Further, the host computer 1 executes a data request SCSI command to receive the data (S6). On the other hand, received data is sent from the communication adapter 2 (S7). After the transmission of the received data has been performed for a certain period of time, the host computer 1 again checks whether or not there is data received from outside in the communication adapter 2.
Confirm using the I command (S8). At this time, since there is no received data, a confirmation response indicating that there is no received data is made from the communication adapter 2 (S9), and a series of receiving data fetching operations ends.

[0007]

However, in the conventional data communication apparatus as described above, when communication at a communication speed of 2400 bps to 115.2 kbps is performed by IrDA, it is performed at the time of frame encoding and decoding processing. CRC calculation, transparency control, header, ender,
Each operation of adding and separating the CRC is performed by the host computer 1
Is executed by software. However, if the processing capability of the host computer 1 is low, there is a problem that the addition of the encoding and decoding processing lowers the execution efficiency of other processing.

When the host computer 1 reads the received data from the communication adapter 2, as described above, the host computer 1 uses the confirmation SCSI command for confirming whether or not there is data to be received by the communication adapter, the data length, and the like. Since at least three types of SCSI commands, a request SCSI command and a data request SCSI command, must be executed, there is also a problem that it is not suitable for extracting received data at high speed.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a data communication apparatus capable of executing, in a communication adapter, encoding and decoding processes for transmitting and receiving data in order to solve the above problems.

[0010] The present invention also provides a minimum SC mode without the host computer using different SCSI commands.
It is a second object of the present invention to provide a data communication device capable of extracting received data by executing an SI command and performing high-speed data reception.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a data communication apparatus used in a computer system having a SCSI bus, which has a SCSI function as a target and is provided on the SCSI bus. A communication adapter connected thereto; and a host computer having a SCSI function as an initiator and connected to the SCSI bus. The communication adapter decodes transmission data and decodes reception data. Means. In this data communication device, it is possible to perform data transmission in frame units between the host computer and the communication adapter.

According to the present invention, in the above data communication apparatus, the host computer sends a SCSI command for receiving data to the communication adapter, and the communication adapter immediately transmits the received data when the received data exists. The gist is that dummy reception data is transmitted to the host computer when the reception data does not exist while transmitting the data to the host computer.

With this configuration, when performing data communication using the SCSI function, the encoding and decoding processes of the frame are executed by the communication adapter, so that the processing load on the host computer is reduced, and the communication control and the like are reduced. The execution efficiency of other processing can be improved. Also, when the host computer retrieves the received data from the communication adapter, the host computer only issues a data request SCSI command to the communication adapter.
It is possible to cope with the case where the communication adapter has received data or not, so that the processing can be simplified and high-speed data reception can be performed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a data communication apparatus is provided with a SCSI as an initiator.
A host computer having a function, a communication adapter having a SCSI function as a target, and a SCSI bus connecting the host computer and the communication adapter are provided, and the communication adapter encodes transmission data. Means and means for decoding received data. When data communication using the SCSI function is performed, encoding and decoding of frames are executed in the communication adapter, so that processing in the host computer is performed. This has the effect of reducing the burden and improving the execution efficiency of other processing such as communication control.

According to a second aspect of the present invention, in the data communication apparatus according to the first aspect, data transmission is performed in frame units between the host computer and a communication adapter. This has the effect of reducing the number of SCSI command numbers depending on the frame configuration.

According to a third aspect of the present invention, in the data communication apparatus according to the second aspect, a frame used for data transmission in frame units between the host computer and the communication adapter is included. The information for indicating the data length of the received data is incorporated therein, and the SC for confirming the received data length from the host computer to the communication adapter.
This has the effect that transmission of the SI command can be omitted.

According to a fourth aspect of the present invention, in the data communication apparatus according to the first aspect, the host computer sends a SCSI command for receiving data to the communication adapter, and the communication adapter transmits the SCSI command to the communication adapter. Is to transmit the received data to the host computer immediately when the received data exists, while transmitting the dummy received data to the host computer when the received data does not exist. The transmission of the SCSI command for confirming the presence or absence of the received data from the communication adapter to the communication adapter can be omitted.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a data communication device according to the present invention. In FIG. 1, reference numeral 11 denotes a host computer which performs various arithmetic processes and includes storage means such as a hard disk and a memory, and can create, store, and save communication data such as text data and image data. Host computer 11
Has a function as a SCSI initiator,
A SCSI command is sent to the communication adapter 12 via the SCSI bus.

Reference numeral 12 denotes a communication adapter which has a function as a SCSI target and
According to the SCSI command from the host computer 1, the data of the host computer 11 is transmitted to the outside, or the data received from the outside is transmitted to the host computer 11. In order to control these data transfers, the communication adapter 12 has two types of status information using software registers or hardware registers. One is a communication line status, which indicates a state in which data is to be sent from the outside to the communication adapter 12. The other is a SCSI status, which has both reception data bits and transmission data bits. The received data bit indicates that data to be sent to the host computer 11 via the SCSI bus has been received from the outside. The transmission data bit indicates that data to be transmitted to the outside has been received from the host computer 11 via the SCSI bus. Reference numeral 13 denotes a SCSI bus to which the host computer 11 and the communication adapter 12 are connected. Reference numeral 14 denotes a communication line connected to the communication adapter 12. In this embodiment, the communication adapter 12 includes an encoder 21 for encoding transmission data when transmitting data, and a decoder 22 for decoding reception data when receiving data. The encoder 21 is connected to the host computer 11 via the data bus 20, while the decoder 22 is connected to the host computer 11 and the SCSI.
It is connected via a bus 13.

FIG. 2 is a block diagram showing a configuration example of the communication adapter 12. As shown in FIG. In FIG. 2, reference numeral 15 denotes C
A PU, which operates the communication adapter 12 on the SCSI bus 1
3 and controls the operation of the entire functional unit inside the communication adapter 12. 16 is
It is a ROM and stores a control program of the CPU 15. A communication control unit 17 transmits and receives data to and from the outside via the communication line 14. Reference numeral 18 denotes a SCSI controller, which has a function as a target, and transmits and receives data to and from the host computer 11 via the SCSI bus 13. Reference numeral 19 denotes a buffer memory (using a semiconductor memory), which stores data transmitted and received by the SCSI controller 18 and data transmitted and received by the communication controller 17. The buffer memory 9 may use a semiconductor memory, or may be a hard disk or other storage means. Reference numeral 23 denotes a bus, and each functional unit 16, 17, 18, 19, 21, 2 in the communication adapter 12.
2 is connected to the CPU 15 via the bus 23. The communication line 14 through which the communication adapter 12 transmits and receives data to and from the outside is a wired line, a wireless line, or an IrDA
(A line using optical communication).

In the data communication device having such a configuration, the following operation is performed between the host computer 1 and the communication adapter 2. FIG. 3 is a time sequence diagram illustrating the operation of the data communication device according to the present embodiment. In this data communication device, first, the communication adapter 12 receives received data from outside (S1).
1) shall be. The decoder 22 of the communication adapter 12 decodes the received data and converts the data into a frame structure transmitted between the communication adapter 12 and the host computer 11. FIG. 4 shows an example of this frame structure. As is apparent from FIG. 4, the received data 30 includes a valid data length field 31 and an address field 32.
, A control field 33, and a data field 34. Valid data length field 3
2 incorporates information about the effective length of the data.

When the host computer 11 wants to take in the received data, the host computer 11 executes the data request SCSI command without confirming whether the communication adapter 12 has data received from outside (S12). ). On the other hand, from the communication adapter 12, the currently received data 3
0, the received data 30 is stored in the host computer 1
1 (S13). After the transmission of the reception data 30 has been performed for a certain period of time, the host computer 11
Executes the SCSI command for data request in order to take the data received from the outside into the communication adapter 12 again.
(S14). Since there is no received data 30 at this time, a process of transmitting dummy received data to the host computer is performed from the communication adapter 12 (S1).
5), a series of reception data fetching operation ends.

In such a processing operation, the host computer 11 does not send a confirmation SCSI command to the communication adapter 12 to confirm whether the communication adapter 12 has data received from outside. Even if the processing is performed, the reception data 30 is transmitted from the communication adapter 12 to the host computer 11 when the reception data 30 exists, while the reception data 30 is transmitted to the host computer when the reception data 30 does not exist. Is transmitted to the host computer, whereby the host computer 11 can indirectly determine the presence or absence of the received data. Further, in the above processing operation, the host computer 11 does not execute the data length request SCSI command for checking the data length of the received data with respect to the communication adapter 12; As is clear from the frame structure of the received data, the valid data length field 31 is allocated in the frame structure. Therefore, when the received data is sent, the host computer 11 decodes the frame to receive the data. The data length of the data can be recognized. As the frame structure of the dummy received data, a structure similar to that described above with reference to FIG. 4 is used. It is created by a method of describing information with a data length of "0" or writing information of all "0" therein as information of the data field 34.

Next, the operation of transmitting and receiving data from the communication adapter 12 to the host computer 11 will be described with reference to the flowchart shown in FIG. When this transmission / reception operation is started, a processing step (hereinafter simply referred to as a step)
At 41, a data receiving operation is performed. In “data reception” in step 41, the reception of the entire frame of the reception data 30 is executed. Next, the data received in step 42 is the beginning of the received data 30 (Beginn).
ing of Frame), and if it is the head of the received data, the data reception process of step 41 is executed again. On the other hand, when it is determined in step 42 that the received data is not the head of the received data 30, the address field 32 is stored, and the FCS check (frame check sequence) is started.
Next, in step 44, the next data reception (frame reception) is executed, and in step 45, the control field 33 is stored. Next, in step 46, the next data reception (frame reception) is executed.
In this processing step, the data field 34 is fetched. Then, in the next step 47, it is checked whether or not the capture of the data field 34 has been completed.
Is received, and the capture of the data field 34 is continued. On the other hand, if it is determined in step 47 that the reading of the data field 34 has been completed, the FCS check is completed in step 48, and then data reception is performed in step 49. Then, in step 50, the FCS (or CRC) is stored, and in step 51, whether the result of the FCS (or CRC) check is good or bad (OK or NG) is checked. In step (3), the frame reception is OK, while if it is defective, in step 53, the frame reception is NG.

As described above, since the data receiving operation is executed without executing various SCSI commands and without performing encoding and decoding of data in the host computer 11, the load on the host computer 11 is reduced. In this state, data reception is performed at high speed.

[0026]

As described above, according to the present invention, S
A data communication device used in a computer system having a CSI bus, the communication adapter having a SCSI function as a target and being connected to the SCSI bus,
The above-mentioned SCSI having a SCSI function as an initiator
A host computer connected to a bus; and the communication adapter having a means for encoding transmission data and a means for decoding received data. Execution efficiency of other processing such as control can be improved.

Further, when the host computer takes out the received data from the communication adapter, the host computer only issues a SCSI command of a data request to the communication adapter, so that the communication adapter can cope with the presence or absence of the received data. In addition, the processing can be simplified, and effects such as high-speed data reception can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a data communication device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a communication adapter used in the embodiment.

FIG. 3 is a time sequence chart for explaining the operation of the data communication device according to the embodiment;

FIG. 4 is a diagram showing an example of a frame structure of data received by the data communication device according to the embodiment.

FIG. 5 is a flowchart illustrating a flow of a data transmission / reception processing operation from the communication adapter to the host computer according to the embodiment.

FIG. 6 is a block diagram showing a schematic configuration of a conventional data communication device.

FIG. 7 is a block diagram showing a configuration of a communication adapter used in a conventional data communication device.

FIG. 8 is a time sequence diagram illustrating an operation of a conventional data communication device.

[Explanation of symbols]

 Reference Signs List 11 host computer 12 communication adapter 13 SCSI bus 14 communication line 15 CPU 16 ROM 17 communication control unit 18 SCSI control unit 19 buffer memory 20 data bus 21 encoder 22 decoder 23 bus 30 received data

Claims (4)

[Claims] A host computer having a SCSI function as an initiator and an SCS as a target
A communication adapter having an I function, and a SCSI bus for connecting the host computer and the communication adapter. The communication adapter has a means for encoding transmission data and a means for decoding reception data. Characteristic data communication device. 2. The data communication apparatus according to claim 1, wherein data transmission is performed in frame units between said host computer and a communication adapter. 3. The frame according to claim 2, wherein information indicating the data length of the received data is incorporated in a frame used for data transmission in frame units between the host computer and the communication adapter. Data communication device. 4. The host computer sends a SCSI command for receiving data to the communication adapter, and the communication adapter immediately transmits the received data to the host computer when the received data exists. 2. The data communication device according to claim 1, wherein when no reception data exists, dummy reception data is transmitted to the host computer.