JPH10320141A - Communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer communication control method capable of transmitting data from a printer to a host without changing an interface. SOLUTION: When a data transfer command is sent to a printer (step S1), the printer starts a mode for transferring data to the host. In order to check whether the printer can send data to the host or not, STB signals are transmitted to the printer continuously eight times (step S2). When the printer has a data transmitting function, a transfer start command for instructing a data transfer start is transmitted to the printer (step S4). Then BUSY signals are transmitted from the printer to the host synchronously with the STB signals (steps S5 to S7). After receiving all transmitting data, the data transfer mode is ended (step S9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a communication control method, and more particularly to a communication control method for transmitting data from a printer to a host.

[0002]

2. Description of the Related Art Usually, a printer used for printing character data, image data, and the like performs a printing process based on data input from an external device (host) such as a computer. Such data transmission and reception between the host and the printer is usually performed via a Centronics interface.

In a configuration using the Centronics interface, as shown in FIG.
Various signals are transmitted and received between and the host 20.
These signals are, for example, as shown in FIG.
A data strobe signal (hereinafter, referred to as an "STB signal") indicating that valid data has been transmitted to the printer 10 from 0, the host 10 is informed that the printer 10 is operating, or that data has been received. Reference numeral 20 denotes a printer processing signal (hereinafter, referred to as a "BUSY signal"), and a data signal for the host to send data to the printer (hereinafter, referred to as a "DATA signal").

[0004] Here, the STB signal and the BUSY signal other than the DATA signal are signals for controlling communication between the host and the printer, and are called control signals. Also, D
The ATA signal is actually an 8-bit width parallel signal.

FIG. 7 shows a communication procedure between a host and a printer performed via a Centronics interface in the prior art. That is, the host 20 sets the data to be sent to the printer 10 in the DATA signal. Then, enable the STB signal (fall the STB signal)
Indicates that the data is valid for the printer 10.

When the printer 10 confirms that the STB signal has become valid by detecting the falling of the STB signal, the printer 10 raises the BUSY signal to raise the BUY signal.
The data is read by making the SY signal valid. Further, the printer 10 invalidates the BUSY signal by lowering the BUSY signal after reading. As a result, the host 20
Is notified that the printer 10 has read the data. When confirming that the BUSY signal has become invalid, the host 20 sets the next data in the DATA signal. Thereafter, the procedure is repeated to transmit data to the printer 10.

[0007]

However, in the above-mentioned prior art, data can be sent from the host to the printer only in one direction, and the status of the printer is being operated from the host by, for example, a BUSY signal. I can only know. Therefore, in order for a user or an operator to know the status of the printer, for example, printer setting information or the content of an error on the printer side when a print error occurs, the operator must actually check the printer. Did not.

It is an object of the present invention to provide a communication control method capable of transmitting data from a printer to a host using a current interface, that is, without changing the interface.

[0009]

According to the communication control method of the present invention, a host and a printer are connected via an interface having a data output line and a control signal line from the host to the printer, and a control signal line from the printer to the host. A mode change step of transmitting a mode change command from the host to the printer to enter a mode for transferring data from the printer to the host, and a transfer instructing the start of data transfer from the printer to the host. A transfer start step of transmitting a start command from the host to the printer; and a data transmission step of transmitting data from the printer to the host via the control signal line.

Further, the communication control method of the present invention further comprises, after the mode change step, a confirmation step of confirming whether or not the printer is compatible with the data transfer, wherein the printer is adapted to the data transfer. The data transmission step is performed only when it is confirmed that

More specifically, the confirmation in the confirmation step includes transmitting a predetermined signal from the host to the printer,
This is performed by the host receiving a response signal from the printer to the predetermined signal.

The interface used in the present invention is, for example, an interface conforming to the Centronics specification or an interface conforming to the Centronics interface.

According to the communication control method of the present invention, various data is transmitted from the printer to the host using a control signal line from the printer to the host. The transmission of the mode change command, the transfer start command, or the predetermined signal from the host to the printer is performed using a data output line or a control signal line from the host to the printer. Also, a control signal line from the host to the printer is used. With such a configuration, data can be transmitted from the printer to the host using the current interface.

[0014]

Embodiments of the present invention will be described below. FIG. 1 shows a communication system to which the communication control method according to the embodiment is applied. This communication system includes a printer 10 and a host 20. Printer 10
An interface unit 11 for transmitting and receiving data and signals to and from the host 20, a control unit 12 for controlling various processes in the printer 10, and a predetermined printing process based on the data and signals transmitted from the host 20. And a printing mechanism 13. The host 20 includes an interface unit 21 for transmitting and receiving data and signals to and from the printer 20, and a control unit 22 for controlling various processes in the host 20.

The interface units 11 and 21 are:
It corresponds to a Centronics interface, and a signal line for an STB signal, a signal line for a BUSY signal, a signal line for a DATA signal, and the like are provided between these interface units 11 and 21, for example, as shown in the figure. .

Next, a communication control method according to the embodiment will be described with reference to FIGS. Here, FIG. 2 is a flowchart for explaining a communication procedure in the embodiment, and FIGS. 3 to 5 are time charts for explaining the operation in the embodiment. The following operations are performed by the printer 10.
Or the control unit 22 of the host 20.

Referring to FIG. 1, for example, when the user wants to know the setting information of the printer, and performs an operation for the host 20, the controller 22 outputs a data transfer command therefor. . This data transfer command is transmitted from the interface unit 21 to the DATA
The signal is input to the interface unit 11 of the host 10 via a signal.

In the present embodiment, the data transfer command is specifically "00H" data, which is sent to the printer (step S1). In addition, this "00
In the printer 10, the data transfer command including the “H” data is transmitted to the control unit 1 via the interface unit 11.
2 is input. The control unit 12 determines this data transfer command and enters a mode in which data is transferred from the printer 10 to the host 20 (data transfer mode). The reason why "00H" is used as the data transfer command is to prevent erroneous characters in the printer.

Next, the host 20 transmits to the printer 10 whether or not the printer 10 supports the data transfer command, that is, the printer 10 can transmit printer setting information and the like to the host 20. Check if there is. Specifically, as shown in FIG. 3, this is performed by continuously transmitting the STB signal eight times from the host 20 to the printer (Step S).
2). Then, in the data transfer mode, when these STB signals are input from the host 20, the printer 10 transmits a BUSY signal to the host 20 as a response signal as shown in FIG.

If there is no response by the BUSY signal from the printer 10, the host 20
0 determines that it does not have the data transmission function, and ends the data transfer mode from the printer 10 to the host 20 (step S9). Thereafter, the host 20 performs conventional processing and performs data communication with the printer 10.

On the other hand, if there is a response by the BUSY signal from the printer 10, the host 10 determines that the printer 10 has a data transmission function. Then, as shown in FIG. 4, a transfer start command instructing the start of data transfer from the printer 10 to the host 20 is transmitted to the printer 10 on a DATA signal (step S4).

Then, while the transfer start command is being output, the host 20
The TB signal falls (step S5). At the falling timing of the STB signal, the printer 10 sets transmission data to the host 10 on the BUSY signal (step S6).

Here, assuming that the transmission data is n bits, one bit of the n bits is set on the BUSY signal. Then host 2
0 starts the STB signal, and at this timing, the BUSY
The data on the signal is read (step S7). That is, the printer 10 sets data to the BUSY signal in synchronization with the STB signal to the host 20, and the host 20 reads data on the BUSY signal at the rear edge of the STB signal.

Next, the host 20 determines whether n bits required as transmission data have been received (step S).
8). If n bits have not been received, the process returns to step S5. Then, the host 20 raises the STB signal, the printer 10 sets one bit of data on the BUSY signal, and the host 20 sets the B at the rear edge of the STB signal.
The process of reading data on the USY signal (steps S5 to S8) is similarly repeated.

The above process is executed by the host 20 by the printer 1
This operation is repeated until all the received data of 0 to n bits are received. When the host 20 has received all the received data, the host 20 stops transmitting the transfer start command, and the data transfer mode from the printer 10 to the host 20 ends (step S9).

FIG. 5 shows the detailed timing when the host 20 reads 1-bit data set on the BUSY signal from the printer 10. This 1-bit data is set between T2 and T3,
0 reads this data at the timing between T2 and T1. Here, in FIG. 5, for example, T1 ≦ 0.5 μ
S, T2 ≦ 1.0 μS, T3 ≦ 0.5 μS.

[0027]

As described above, according to the communication control method of the present invention, data can be transmitted from the printer to the host with the conventional interface, and the printer setting information and the error generated in the printer can be performed. Can be easily known by the host.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a communication system to which a communication control method according to an embodiment of the present invention is applied.

FIG. 2 is a flowchart showing a procedure of a communication control method according to the embodiment of the present invention.

FIG. 3 is a time chart illustrating an operation of the communication system of FIG. 1;

FIG. 4 is a time chart illustrating an operation of the communication system of FIG. 1;

FIG. 5 is a detailed time chart when reading data on a BUSY signal in FIG. 4;

FIG. 6 is an explanatory diagram of signal transmission / reception by an interface between a printer and a host in the related art.

FIG. 7 is an explanatory diagram of the operation of the conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Printer 11, 21 Interface part 12, 22 Control part 20 Host

Claims (3)

[Claims] 1. A communication control method between a host and a printer via an interface having a data output line and a control signal line from the host to the printer and a control signal line from the printer to the host. Mode change step for transmitting a mode change command from the host to the printer to enter a mode for transferring data to the printer, a transfer start step for transmitting a transfer start command from the host to the printer for instructing the start of data transfer from the printer to the host And a data transmission step of transmitting data from the printer to the host via the control signal line to the host. 2. The method according to claim 1, further comprising a step of confirming whether the printer is compatible with the data transfer, following the mode changing step. 2. The communication control method according to claim 1, wherein the data transmission step is performed only in the data transmission step. 3. The method according to claim 1, wherein the confirmation in the confirmation step comprises transmitting a predetermined signal from the host to the printer, and receiving a response signal from the printer to the predetermined signal at the host. Or the communication control method according to 2.