JPH0199154A - Data transmitter - Google Patents

Abstract

PURPOSE:To enable bidirectional data transmission by providing a data input port on an interface of the computer side with a data input port, and switching the data-direction at a data input/output port provided on an interface of the device side by means of a command outputted to a data output port provided on the computer side. CONSTITUTION:The data input port 3'' through which data from the device 10 is inputted is provided on the computer side interface (centronics-interface 1) while the bidirectional data input/output port 11' instead of a data input port is provided on the interface of device 10 side. The data direction at the port 11' is switched by a command outputted to the data output port 3 provided on the interface 1 of the computer side. As a result, bidirectional data transmission is enabled without largely modifying the constitution of a standard above- mentioned interface 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data transfer device that transfers data between a computer and various devices.

[Conventional technology]

There are various methods for transferring data between computers and various devices connected to them.
One of these is the Centronics interface specification.

Conventionally, this Centronics interface specification was an interface designed for devices such as printers that only input data, and data could not be transferred from the device to the computer. However, recently, examples have emerged in which the Centronics interface is used as a bidirectional input/output interface that not only transfers data from a computer to a device, but also from a device to a computer.

An example of a conventional unidirectional Centronics interface for transferring data from a computer to a device is illustrated in FIG. 1 is the computer's Centronics interface. , 2 is a data bus within the interface 1, 3 is a data output port connected to data bus 2, 4 is an output port that outputs the 5TROB signal to the device, and 5 is an input port for receiving the ACK signal and BUSY signal from the device. 6 is a data line connecting the Centronics interface 1 on the computer side and the device, 7 is the 5TROB signal line from the computer to the device (goods), 8 is the ACK signal line from the device to the convenience store, 9 is the BUSY signal line from the device Mi to the combination converter, 10 is the above device, 11 is the data port for inputting data from the computer installed in the device 10, and 12 is the 5TR
Input port for inputting OB signal, 13 is ACK signal and B
An output port 14 that outputs the USY signal is a control device that controls these inputs and outputs.

Next, the operation of the example shown in FIG. 5 will be explained with reference to the time chart shown in FIG. At time point a shown in FIG.

The computer inputs the BUSY signal through the input port 5 and outputs data to the data output port 3 if the device 10 is in a state where data can be input. Then, once the output data has stabilized, the computer temporarily drops the 5TROB signal to low level via the output port 4, indicating that the data is valid and requesting the device 10 to input the data. The controller 14 of the device 10 inputs this 5TROB signal via the input port 12 and inputs the data at time C via the data input port 11, and also inputs secondary data during input processing and processing of the input data. The BUSY signal is kept high until data can be accepted, informing the computer that data cannot be accepted.

At time d, the device 10 finishes processing the data, and when the next data can be input, returns the BUSY signal to low level, further sets the ACK signal to low level for a part of the time, and tells the computer that the data processing has finished, Proceed to request the next data transfer. The computer receives this ACK
By inputting the signal and the BUSY signal, data is again outputted to the data output port in the same manner as at time a, and thereafter data transfer is performed one after another in the same manner.

A conventional data transfer device in which the Centronics interface is bidirectional will be described with reference to FIG. In FIG. 7, the same parts as in FIG. 5 are given the same reference numerals.

Reference numeral 3' denotes an input/output data port connected to the data bus 2, and is a bidirectional port configured so that input and output are switched by a DIR signal. Also, 4' is 5TRO
Input/output port that switches input/output direction of B signal by DIR signal, 5' is ACK signal input port, 5# is B
The input/output port 6' switches the input/output direction of the USY signal by the DIR signal, and is a data line connecting the computer and the device 10, and transfers data in both directions. 7' is the 5TROB signal line, which is 5T in both directions.
Transfer ROB signal. 9' is a BUSY signal line, which transfers the BUSY signal in both directions. 11' is a data input/output port in the device 10, and the data input/output port switches the transfer direction by the DIR signal. 12' is the human output port which switches the input/output direction of the 5TROB signal by the DIR signal. 13' is the ACK signal. Output port 13" is an input/output port that switches the input/output direction of the BUSY signal by the DIR signal, 15 is an output port that outputs the DIR signal, 16 is a DIR signal line, 1
7 is an input port for inputting the DIR signal, and 14' is a control device for controlling these ports.

Next, the operation of the apparatus shown in FIG. 7 will be explained with reference to the time chart shown in FIG. At time a in FIG. 8, when the DIR signal output from the output port 15 is at a high level, the data input/output port 3' is in the output direction, and the 5T
The input/output port 4' that outputs the ROB signal is in the output direction, B
The input/output port 5'' to which the USY signal is input is in the input direction.Furthermore, in the device 10, the DIR signal is input to the input port 1.
7, and the data input/output port 11' is the input direction.
The input/output port 12' which inputs the 5TROB signal is in the input direction, and the input/output port 13# which outputs the BUSY signal is in the output direction.

In other words, when the DIR signal is high level, the DATA signal
5TROB signal and BUSY signal are in the same direction as the normal Centronics interface 1 shown in FIG. Transfer data to device 10 via interface 1.

Next, at time e in FIG. 8, when the computer wants to enter a mode for inputting data from the device 10, the output port 15
The output DIR signal is set to low level. Then,
The data input/output port 3' is in the input direction, the input/output port 4' which inputs the 5TROB signal is in the input direction, and the input/output port 5'' which outputs the BUSY signal is in the output direction. input the signal,
The data input/output port 11' is in the output direction, the input/output port 12' is in the output direction so as to output the 5TROB signal, and the BU
The input/output ports 13" are respectively switched in the input direction so as to input the SY signal. Next, at time f, the device 10
is the BU from the computer via input/output port 13”.
The SY signal is input, and when the BUSY signal is at a low level, data is output to the data input/output port 11'.

Until the point g when the output data becomes stable, the device 10 makes the 5TROB signal from the input/output port 12' low level for a part of the time, and requests the computer to receive data. At this point, the computer has 5TR from input/output port 4'.
When the OB signal is input and the 5TROB signal is at a low level, it is known that the device 10 is outputting data, and the data is input through the data input/output port 3', and at the same time, a high level signal is output from the input/output port 5''. It outputs a BUSY signal to inform the device 10 that input data is being processed and the next data input is not possible.

At time point i, when the computer has finished data input processing and is ready to input the next data, it outputs a low-level BUSY signal from input/output port 5, and the input data processing is finished and the next data input is enabled by the device. 10. The device 10 inputs the BUSY signal from the input/output port 13", and since it is at low level, the device 10 receives the BUSY signal from the input/output port 13".
Output the data in the same way again. Thereafter, data is transferred one after another in the same manner.

[Problem that the invention seeks to solve]

As explained above, the conventional data transfer device when the Centronics interface is made bidirectional, adds the DIR signal for switching the input/output direction of the input/output port to the standard Centronics interface, and also adds the 5TROB signal and Since the BUSY signal has to be bidirectional, there is a problem in that the configuration of the standard Centronics interface needs to be significantly changed.

This invention was made to solve the above-mentioned problems, and provides a data transfer device that enables bidirectional data transfer without significantly changing the configuration of the standard Centronics interface. The purpose is to

[Means for solving problems]

The data transfer device according to the present invention is provided with a data input port 3'' for inputting data from the device 10 on the computer side interface (Centronics interface 1), and a bidirectional interface in place of the data input port on the device 10 side interface. data input/output port 11
', and the data direction of this data input/output port 11' is determined by the computer side interface (Centronics).
This feature is characterized in that switching is performed by a command output to a data output port 3 of the interface 1).

[Effect]

A command from the computer is transferred to the data input/output port 11' via the data output port 3, and if the content of this command is to switch the input/output port 11' to the input direction, the input/output port 11' will be switched to the input direction. is set, and data from data output port 3 is input. That is,
Data from the computer will be transferred to device 10. Also, if the content of the command is input/output port 11
’ to the output direction, input/output port 1
1' is set in the output direction, and data from the input/output port 11' is output to the data input port 3''. That is, data from the device 10 will be transferred to the computer.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the drawings. !
FIG. 1 is a block diagram showing the configuration of the data transfer device of this embodiment. In FIG. 1, components corresponding to those shown in FIG. 5 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, 3# is a data input port provided on the Centronics interface 1, which is an interface on the computer side, and inputs data from the device 10, and 11' is a data input/output port provided on the interface on the device 10 side. It is a port.

This data input/output port 11' replaces the data input port 11 of FIG. 5 and has bidirectionality.

The control device 14'' in the device 10 controls the input/output signals of the device 100, and the data input/output port 11
The data input from ' is decoded, and if it is command data, the data direction of the data input/output port 11' is switched according to the content.

Next, the embodiment shown in FIG. 1 will be explained with reference to the time chart shown in FIG. When data is transferred from the computer to the device 10, the data is transferred from time point a to time point d in FIG. 2 in exactly the same manner as the standard Centronics interface shown in FIG. 5. When the computer inputs data from the device 10 at time a', it transfers a data input request command to the device 10 in the same manner as from time a to time d. A command is, for example, an escape sequence often used in printer devices, etc.
Codes that are not used as data, e.g.
The first byte of the command is a code, followed by several bytes of code indicating the contents of the command, and in the case of a data input request, the last byte of the command is FF.An example of this command is shown in the third example. In Fig. 3, ESC is a code indicating a command, ■ is a data input request, E and S are the contents of the requested data, 1.
0 indicates the number of requested data bytes, and FF indicates the end of the command.

At time ', when the device 10 inputs the "FF" code, which is the last byte of the data input request command from the computer, the input/output control unit 14' switches the data direction of the data input/output port 11' to the output side.Next. At time 2, the device 10 outputs data via the data input/output port 11'.Next, at time m, the device 10 drops the BUSY signal to low level via the output port 13 and outputs the ACK signal for a part of the time. The computer is set to low level and requests the computer to receive data.By inputting the low level ACK signal through the input port 5, the computer learns that data is being output from the device 10, and the computer inputs the data input port. Input data from 3″.

The data input from the input/output data port 3# is the data on the data line 6, and this data line 6 has a wired OR between the data output port 3 and the output data of the input/output data port 11'. It becomes data. Since the output data of the data output port 3 is the final data of the command "FF", the data input from the data input port 3" becomes the output data from the device 10. When the processing of the input data is completed and the next data input becomes possible, S T ROB (
No. 8 is kept at low level for a part of the time to request the device 10 to transfer the next data. When the device 10 receives the low-level 5TROB signal through the input port 12, it changes the BUSY signal to high level through the output port 13, outputs data in the same way again at time 1, and thereafter performs the same operation one after another. Output data.

A flowchart showing the operation of the control device 14'' of this device 10 is shown in FIG.

In FIG. 4, device 10 has 5TRO at a low level.
If the B signal is received (step SL), data from the computer via the Centronics interface 1 is input (step 32), and a high-level BUSY signal is output to the computer via the Centronics interface 1 (step S3). . Next, device 10
In step S4), it is determined whether or not there is a command from the computer via the Centronics interface 1. If there is a command, the command is manually inputted in step S5). 11' is to be set in the data output direction (step S7). If this command sets the data output direction, the data input/output port 11' is set to the data output direction (
Step S8), the device 10 has data input/output port 1
1' to the Centronics interface 1 (step 510). Then device 1
0 outputs a low-level BUSY signal to the Centronics interface 1 (step 5ll), and then outputs a low-level ACK signal (step 512).
. When the data output is not completed (step 513) and there is a low level 5TROB signal (
Step 514), returns to step SIO, performs similar processing, and when data output is completed (step 513)
, switches the data input/output port 11' to the data input direction (step 515), outputs a low level BUSY signal (step 816), and outputs a low level ACK signal (step 517). Thereafter, the process returns from step S17 to step S1 and repeats the same process.

Note that when the device 10 determines in step S4 that the command is not a command, it performs normal data processing (step S6) and proceeds to step S16. If it is determined in step S7 that the command is not a data output command, other command processing is performed (step S9), and the process advances to step S16.

According to the above embodiment, by switching the data direction of the device based on a command from the computer, bidirectional data transfer is performed without changing the standard signals of the Centronics interface or adding new signals. be able to.

Note that in the above embodiment, an example is shown in which both the ACK signal and the BUSY signal are used for handshaking for data transfer, but even if only either the ACK signal or the BUSY signal is used for handshaking, the data transfer will not be possible. It is possible.

In addition, although we have shown an example of taking a wired OR on the data line to input data, the same can be said if a circuit is provided that uses a logic circuit to take the AND of the output data from the computer and the output data from the device. be.

〔Effect of the invention〕

As described above, according to the present invention, the computer side interface is provided with a data input port for inputting data from a device, the device side interface is provided with a bidirectional data input/output port in place of the data input port, and this Since the configuration is such that the data direction of the data input/output port can be switched by a command output to the data output port of the computer side interface, bidirectional data can be transferred without major changes to the standard Centronics interface configuration. This has the effect of making transfer possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a data transfer device according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of this embodiment, and FIG. 3 is a diagram showing an example of commands in this embodiment. , FIG. 4 is a flowchart showing the operation of the control device shown in FIG. 1, FIG. 5 is a block diagram showing the configuration of a conventional unidirectional data transfer device, and FIG. 6 shows the operation of the conventional example shown in FIG. FIG. 7 is a block diagram showing a conventional bidirectional data transfer device, and FIG. 8 is a timing chart showing the operation of the conventional example shown in FIG. 1...Centronics interface (computer side interface), 3...Data output port, 3"...Data input port, 4...
...Output port, 5...Input port, 1
0...Device, 11'...Data input/output port, 12...Input port, 13...
... Output port, 14'' ... Control device. Agent: Daikun Masa (2 idiots) Figure 4 Procedural amendment (voluntary) 1. Indication of case Japanese Patent Application No. 1983-256864 No. 2 ,
Name of the invention Data transmission device 3, Person making the amendment Representative Moriya Shiki 4, Agent 5 Column for detailed explanation of the invention to be amended. G. Contents of the amendment (1) In the second line of page 5 of the specification, the word "next and others" is amended to read "chiro". (2) In the 8th line of page 8 of the same book, the phrase ``up to point g'' was replaced with ``
"at time g". that's all

Claims (1)

[Claims] A computer-side interface that has a data output port that outputs data, an output port that outputs a control signal, and an input port that inputs the control signal, an input port that inputs the control signal, and an output port that outputs the control signal. and a device-side interface capable of inputting data, in a data transfer device for transferring data between the computer and the device, a data input port for inputting data from the device to the computer-side interface. A bidirectional data input/output port is provided in the device side interface, and the data direction of the bidirectional data input/output port is switched by a command output to the data output port of the computer side interface. A data transfer device characterized by: