JP2645223B2 - Two-way communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus provided with a line for transmitting data in one direction and a line for transmitting a busy signal in the opposite direction, for example, between a personal computer and a printer. Related to a two-way communication method.

[0002]

2. Description of the Related Art It is generally known that a personal computer and a printer are connected by a Centronics interface (communication protocol). In the Centronics interface, data lines (generally consisting of the number corresponding to the number of bits of data, for example, 8 for 8 bits) for transmitting print information and the like from a personal computer to a printer are provided.
However, a signal line from the printer to the personal computer for transmitting a limited status such as a busy signal (busy signal) indicating whether the printer is in a busy (busy) state (one for each signal) Is provided.

[0003] In addition, when a personal computer and a printer are connected by a simple interface, besides connecting a data line from the personal computer to the printer, only a signal line for transmitting a busy signal from the printer to the personal computer is provided. It may not be provided.

[0004] As a method of transmitting a status not contained in the dedicated signal line from the printer to the personal computer, a signal line for transmitting a strobe signal for setting the timing of receiving print data from the personal computer to the printer is used. In a predetermined sequence, there is a method of transmitting a status by activating or deactivating a busy signal in a predetermined order by using a strobe signal as a trigger.
(See JP-A-2-25140).

[0005]

As the status of the printer, the status of various errors such as out of paper and paper jam, the status of memory capacity, the number of prints, and the like can be considered. It is desired that such a large number of statuses can be arbitrarily confirmed by a personal computer.

In particular, when the personal computer and the printer are installed separately from each other and all operations are performed on the personal computer side, there is a great need to check the status of the printer on the personal computer. However, the conventional interface has a problem that only a limited status can be confirmed.

Further, in the case where the status is sequentially confirmed from the printer to the personal computer by the active or inactive status of the busy signal from the printer by using the strobe signal as a trigger, all of the sequence (
The type and order of the statuses to be checked in the program are determined in advance, the status cannot be arbitrarily selected, and the order of checking cannot be changed.

That is, in order to check the status in the sequence, all types of status that should be checked in all cases must be selected. This ensures that you get the status information you need, but also checks for unnecessary status,
There is a problem that the processing time for status confirmation is long. Further, if the status is selected only for the status considered to be checked in a specific case, there is a possibility that necessary status information may not be obtained in some cases.

Accordingly, the present invention provides a two-way communication method which can arbitrarily select a status to be checked, and thus can reliably obtain necessary status information and shorten the processing time required for status checking. The purpose is to provide.

[0010]

Means and operation for solving the problems] The present invention, a plurality for transmitting data from a first device to a second device
One-way data line composed of parallel signal lines
A first device provided with a busy signal line for transmitting a busy signal from the second device to the first device to indicate whether the second device is busy or not. In a two-way communication method for communication performed between a first device and a second device, a status is transmitted from the first device to the second device.
Command for checking via data line
The second device checks the status based on the command.
Check, and this check result is composed of multiple bits.
To binary data with consecutive bit numbers
Bit data to be output from the first device to the second device.
A data signal having the same value as the bit number of the
Specify data and output timing
Transmitting as a riga over the data line, the second device
Bit data of the bit number specified by the data signal
Is output as a serial signal via the busy signal line.
It is those that.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a personal computer 1 as a first device using a two-way communication method of the present invention and a second computer.
FIG. 2 is a block diagram showing a circuit configuration of a main part of a system including a printer 2 as an apparatus.

The personal computer 1 includes a CPU (central processing unit, hereinafter referred to as a PC side CPU) 11 constituting a control unit main body, and a PC side CPU.
ROM storing the program data of the processing performed by 11
(read only memory, hereinafter referred to as PC ROM) 12
And a RAM (random access) in which areas of various memories used when the PC CPU 11 performs processing are formed.
memory, hereinafter referred to as PC-side RAM) 13, a keyboard 14, a keyboard interface 15 for controlling data transmission with the keyboard 14, a display 16, a display controller 17 for controlling the display 16, an I / O (input / output) ports (hereinafter referred to as PC-side I / O ports) 18 and the like.

The PC CPU 11 is provided with a system bus (
The PC ROM 12, the PC RAM 13, the keyboard interface 15, and the display controller 1 are connected via a PC system bus 19.
7, connected to the PC side I / O port 18 and the like.

The PC side I / O port 18 is provided with an input port 18-1 having an input terminal for inputting various signals such as a busy signal input terminal for inputting a busy signal, and a data for transmitting data. Output terminal (8 terminals for 8 bits)
And an output port 18-2 having an output terminal for outputting various signals such as a strobe signal.

The printer 2 has a CPU 21 constituting a control section main body, a ROM 22 storing program data for processing performed by the CPU 21, and various memory areas used when the CPU 21 performs processing. A RAM 23, a printer engine 24, a printer engine controller 25 for controlling the printer engine 24, a paper transport unit 26 for transporting the paper, a paper transport controller 27 for controlling the paper transport unit 26,
/ O port 28 and the like.

The CPU 21 is connected to the ROM 22, the RAM 23, the printer engine controller 25, the paper transport controller 27, the I / O port 28 and the like via a system bus 29.

The I / O port 28 has an output port 28-1 having an output terminal for outputting various signals such as a busy signal output terminal for outputting a busy signal, and a data input terminal for receiving data. (8 terminals for 8 bits), stro
an input port 28-2 having an input terminal for inputting various signals such as a be signal.

A line connected between the busy input terminal of the input port 18-1 of the PC side I / O port 18 and the busy output terminal of the output port 28-1 of the I / O port 28 (
busy line) constitutes a second line in the reverse direction,
A line (data line) connected between the data output terminal of the output port 18-2 of the C-side I / O port 18 and the data input terminal of the input port 28-2 of the I / O port 28
Constitutes a first line in one direction.

FIG. 2 is a diagram showing a flow of a status receiving process performed by the PC-side CPU 11 of the personal computer 1. First, a status request command corresponding to the confirmed printer status is transmitted to the printer 2 from the data output terminal of the output port 18-2 of the PC I / O port 18.

Next, the transmitted status request
Printer status corresponding to the command
Are ready for transmission to the personal computer 1.

When the printer 2 is ready for transmission,
The printer enters a bidirectional communication mode (hereinafter, referred to as a status reply mode) for transmitting and receiving printer status using the busy signal line between the personal computer 1 and the printer 2.

Step 1 of status reply mode
In the process of ST1), the data ID corresponding to the required bit data in the printer status mode to be confirmed is transmitted from the data output terminal of the output port 18-2 to the printer 2.

When the transmission of the data ID is completed, a preset standby time is measured. When the measurement of the standby time is completed, the input port 18-1 of the PC I / O port 18 is started.
Check the signal input to the busy signal input terminal of P. and change the state of the busy signal (High = 1 / Low = 0) to P
It is recorded in the C-side RAM 13.

Here, it is determined whether or not further necessary bit data remains for the currently confirmed printer status data. If necessary bit data remains, the above-described steps are repeated. It returns to the process of 1. If all necessary bit data checks have been completed, the end ID is transmitted from the data output terminal of the output port 18-2 to the printer 2, and the status reply mode is ended.

If so, the status receiving process ends. FIG. 3 is a diagram showing a flow of a status transmission process performed by the CPU of the printer 2.

First, the input port 28 of the I / O port 28
Check the data received by the -2 data input terminal. If the received data is a status request command, the status data corresponding to the status request command is stored in the RAM 23.
Preparation for transmission to the personal computer 1 is performed. At this time, the personal computer 1 enters the standby state as described above.

When the preparation for transmitting the status data is completed, the printer 2 and the personal computer 1 enter a status reply mode. First, step 2 (S
In the process of T2), the data ID received at the data input terminal of the input port 28-2 is checked, and from the status data recorded on the RAM 23, the data I
The bit data corresponding to D is extracted.

Next, this bit data is set to the busy signal output terminal of the output port 28-1 (High = 1 / Low = 0) within a preset time and transmitted to the personal computer 1 as a serial signal. .

When the output of the bit data by the busy signal is completed, the newly received ID is checked at the data input terminal of the input port 28-2. Here, if the received ID is a data ID requesting transmission of untransmitted bit data among the status data recorded on the RAM 23, the process returns to the above-described step 2 again. If the received ID is the end ID, the status reply mode is ended.

With the above, the status transmission processing ends. When the status transmission process is completed, the printer 2 returns to the normal mode, for example, to a normal process such as a drawing / printing operation.

In this embodiment having such a configuration, a unique status request command and a unique length status command are provided for various statuses of the printer 2.
Data is set.

The personal computer 1 is connected to the printer 2
When the status check is performed, first, a unique status request command corresponding to the printer status to be checked is transmitted to the printer 2 via the data line. Then, the printer 2 prepares status data of a specific length corresponding to this, waits for the completion of the transmission preparation, and then enters the status reply mode.

Upon receiving the status request command, the printer 2 prepares status data of a specific length corresponding to the status request command, and switches to the status reply mode when the preparation for transmitting the status data to the personal computer 1 is completed. enter.

When the personal computer 1 enters the status reply mode, the personal computer 1 transmits a data ID corresponding to the required arbitrary bit data among the status data to be confirmed to the printer via the data line, and responds to the data ID. The bit data is received from the printer 2 via the busy signal line.

When the printer 2 enters the status reply mode, the printer 2 checks the data ID transmitted from the personal computer 1 via the data line, and outputs bit data corresponding to the data ID from the prepared status data to a busy signal. The data is transmitted to the personal computer 1 via the line.

In this embodiment, when a status request command is transmitted from the personal computer 1 to the printer 2, the printer 2 prepares status data having a unique length composed of a plurality of bits corresponding to the status request command. This status data has a single meaning in the entire status data of a plurality of bits, such as the total number of printed pages, and each bit of the status data, such as an error state of the printer, is, for example, out of paper or paper jam. And so on, each having a different meaning.

Therefore, when the personal computer 1 acquires the total number of print pages from the printer 2 as the printer status, first, the personal computer 1 sends a status request command corresponding to the total number of print pages to the printer 2 via the data line. Send.

Next, in order to obtain all bits of the status data, a data ID (
For example, if the status data is 32 bits, bits 0 to 31 have data IDs “00” and “3”, respectively.
1) is sequentially transmitted to the printer 2 via the data line.

Each time the data ID is transmitted, the corresponding bit data is obtained as a serial signal from the printer 2 via the busy signal line. Finally, the status data is obtained by synthesizing the bit data obtained as serial data.

When the personal computer 1 acquires the printer error status as the printer status, the personal computer 1 first transmits a status request command corresponding to the printer error status to the printer 2 via the data line.

Next, to obtain, for example, the out-of-paper status from the status data,
Data ID corresponding to the bit that stores the out-of-paper state in the data (for example, the out-of-paper state is bit 3
Is transmitted to the printer 2 via the data line, and the bit data corresponding to the data ID "03" is transmitted to the printer 2 via the data line. The status is obtained from the printer 2 via the busy signal line.

As described above, according to the present embodiment, the personal computer 1 has the status request command corresponding to the printer status to be confirmed and the data ID corresponding to the bit data actually required in the status data. To the printer, and upon receipt of this, the printer 2 prepares status data corresponding to the status request command, and among these, bit data corresponding to the data ID as a serial signal.
The data is transmitted to the personal computer 1 via the busy signal line. The personal computer 1 confirms the status of the printer 2 by receiving the serial signal. With this two-way communication method, the personal computer 1 can arbitrarily select the status of the printer 2 to be checked, can reliably acquire necessary status information, and can process time required for status confirmation. Can be shortened.

That is, by using a status request command corresponding to the printer status to be checked, each status of the printer can be directly checked if necessary, and by using the data ID, Only the minimum data actually required among the status data to be checked can be directly and arbitrarily checked.

[0044]

As described in detail above, according to the present invention,
It is possible to arbitrarily select a status to be confirmed, and thus to provide a two-way communication method capable of reliably obtaining necessary status information and shortening the processing time required for status confirmation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main circuit configuration of a system including a personal computer and a printer according to an embodiment of the present invention.

FIG. 2 is an exemplary view showing the flow of a status confirmation process performed by the personal computer of the embodiment.

FIG. 3 is a view showing the flow of status transmission processing performed by the printer of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Personal computer, 2 ... Printer, 11 ... PC side CPU, 18 ... PC side I / O port, 21 ... CPU, 28 ... I / O port.

Continuation of the front page (72) Inventor Tetsuo Kanno 1031 Fujisawa, Fujisawa-shi, Kanagawa Prefecture Apti Co., Ltd. (56) References JP-A-60-157353 (JP, A) JP-A-6-119276 (JP, A)

Claims (1)

(57) [Claims] 1. A method for sending data from a first device to a second device.
To believeConsists of multiple parallel signal lines
One-way data lineAnd the second
The second device is busy from the device to the first device
To send a busy signal indicating whether or notOne busy
Signal lineThe first device provided with the
In a two-way communication method of communication performed between theCheck status from the first device to the second device
Command to send data through the data line.
Believe in The second device returns a status based on the command.
Check and configure this check result from multiple bits
To binary data with consecutive bit numbers
And Bits to be output from the first device to the second device
A data signal having the same value as the data bit number is
And specify the output timing.
Transmit via the data line as a trigger to give, The second device is configured to control a bit designated by the data signal.
Bit number data through the busy signal line.
Output as serial signal Two-way communication
How to trust.