JPH0870337A - Two-way communication method - Google Patents

Abstract

(57) [Summary] [Purpose] The status to be confirmed can be selected arbitrarily to reliably obtain the necessary status information and reduce the processing time required for status confirmation. [Structure] A status request command corresponding to a status to be confirmed is transmitted from a personal computer to a printer, and the printer which receives the status request command prepares status data corresponding to the status request command. Next, the personal computer sequentially transmits the data ID corresponding to the required bit data among the status data to the printer, and the printer which received this transmits the corresponding bit data as a serial signal via the busy signal line. Send to a personal computer. The personal computer confirms the printer status from the serial signal received via this busy signal line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device 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 the 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 this Centronics interface, a data line (generally composed of a number corresponding to the number of bits of data, for example, 8 if 8 bits) is provided for transmitting print information and the like from a personal computer to a printer.
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.

As a method for transmitting from the printer to the personal computer the status not possessed by a dedicated signal line, a signal line for transmitting a strobe signal for timing of receiving print data from the personal computer to the printer Is provided and there is a method of sending the status by activating or deactivating the busy signal in a predetermined order by using the strobe signal as a trigger in a predetermined sequence.
(See JP-A-2-25140).

[0005]

As the status of the printer, various error statuses such as paper out and paper jam, and statuses such as memory capacity and the number of printed sheets can be considered. It is desired to be able to arbitrarily check such a large number of statuses on 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 confirm the status in the sequence, it is necessary to select all kinds of statuses which are considered to be confirmed in all cases. 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 becomes long. Further, if the selection is limited to the status considered to be confirmed in a specific case, there is a possibility that necessary status information may not be obtained in some cases.

Therefore, according to the present invention, the status to be confirmed can be arbitrarily selected, so that the necessary status information can be surely obtained and the processing time required for the status confirmation can be shortened. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION The present invention provides a unidirectional first line for transmitting data from a first device to a second device, as well as a second device to a first device. Communication between a first device and a second device provided with a reverse second line for transmitting to the one device a busy signal indicating whether the second device is busy. In the two-way communication method, the first device sends a status list to be checked to the second device via the first line, and the second device checks the status based on the status list, and the check is performed. The result is converted into signals of 1 and 0, and is output as a serial signal from the second line in the order of the status list.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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.
2 is a block diagram showing a circuit configuration of a main part of a system including a printer 2 as the apparatus of FIG.

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 side 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 (
Hereinafter, the PC side ROM 12, the PC side RAM 13, the keyboard interface 15, and the display controller 1 via a PC side 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 includes 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) or stro
The input port 28-2 is provided with 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 opposite 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 status reception processing 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 side I / O port 18.

Next, the transmitted status request
Printer status corresponding to the command
Is in a standby state until ready to be sent to the personal computer 1.

When the printer 2 is ready for transmission,
A two-way communication mode (hereinafter referred to as a status reply mode) for transmitting / receiving printer status using a busy signal line between the personal computer 1 and the printer 2 is entered.

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

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 and check the status of the busy signal (High = 1 / Low = 0) by 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 the necessary bit data have been checked, the end ID is transmitted from the data output terminal of the output port 18-2 to the printer 2 to end the status reply mode.

The status reception process is completed. 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, as described above, the personal computer 1 enters the standby state.

When the status data transmission preparation is completed, the printer 2 and the personal computer 1 enter the status reply mode. First, step 2 (S
As the processing of (T2), the data ID received at the data input terminal of the input port 28-2 is checked, and the data I among the status data recorded on the RAM 23 is checked.
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 such as drawing / printing operation as the normal mode.

In this embodiment having such a configuration, for each status of the printer 2, a status request command unique to each status and a status command of a unique length
Data is set.

The personal computer 1 is connected to the printer 2
When confirming the status of the above, first, a unique status request command corresponding to the printer status to be confirmed 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 sends a data ID corresponding to any required bit data of the status data to be confirmed to the printer via the data line, and responds to this. Receive bit data from printer 2 via the busy signal line.

When the printer 2 enters the status reply mode, it checks the data ID transmitted from the personal computer 1 via the data line, and selects the bit data corresponding to the data ID from the prepared status data as a busy signal. It 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, each bit data acquired as serial data is combined to acquire status 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, if, for example, the status of paper exhaustion is to be acquired from the status data, the status data
Data ID corresponding to the bit that stores the paper out status in the data (for example, the paper out status is bit 3
If the data is stored in the data ID “03”, and if the data is stored in the bit 5, the data ID “05”) is transmitted to the printer 2 through the data line, and the corresponding bit data, that is, when the paper runs out. The status is acquired from the printer 2 via the busy signal line.

As described above, according to this embodiment, the personal computer 1 has the data ID corresponding to the bit data actually required in the status request command and the status data corresponding to the printer status to be confirmed. To the printer, and the printer 2 receiving this prepares the status data corresponding to the status request command, from which the bit data corresponding to the data ID is converted into a serial signal.
It 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. By this two-way communication method, the personal computer 1 can arbitrarily select the status of the printer 2 to be confirmed, can surely acquire necessary status information, and the processing time required for status confirmation. Can be shortened.

That is, by using the status request command corresponding to the printer status to be confirmed, each status of the printer can be directly confirmed if necessary, and by using the data ID, Among the status data to be confirmed, only the minimum data actually required can be directly and arbitrarily confirmed.

[0044]

As described above in detail, according to the present invention,
It is possible to provide a two-way communication method in which the status to be confirmed can be arbitrarily selected, so that necessary status information can be surely obtained and the processing time required for status confirmation can be shortened.

[Brief description of 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 (51) Int.Cl. ⁶ Identification number Internal reference number FI technical display location H04L 5/14 (72) Inventor Tetsuo Sugano 1031 Fujisawa, Fujisawa-shi, Kanagawa Apty Co., Ltd.

Claims (1)

[Claims] 1. A unidirectional first line is provided for transmitting data from a first device to a second device and the second device to the first device is connected to the second device. Two-way communication method of communication performed between the first device and the second device provided with a reverse second line for transmitting a busy signal indicating whether the device is in a busy state In, the first device sends a status list to be checked to the second device via the first line, and the second device checks the status based on the status list, and checks the status. Result 1 and 0
The signal is converted into a serial signal from the second line in the order of the status list and output as a serial signal.