JPH06274286A - Interface device - Google Patents

Abstract

PURPOSE:To provide an interface circuit capable of informing the detailed trouble contents of a printer to a device for transferring data in accordance with a request from the device concerned by using individual status lines in common without increasing the number of signal lines. CONSTITUTION:At the time of receiving an active strobe signal with a period longer than a prescribed period from a central processing unit (CPU) 10 during the period of outputting a buzy signal indicating a state that a printer 20 can not receive data, a processing means 40 transmits an error code indicating the season of the data unreceivable state to the CPU 10 through plural status signal lines STAT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interface device provided between a printer and a device for transferring data to the printer.

[0002]

2. Description of the Related Art Conventionally, a central processing unit (hereinafter referred to as CPU), which is a higher-level device, and a printer are connected in parallel.
There is a form in which connection is made via an interface. The parallel interface includes parallel data signal lines for transferring data, a plurality of (for example, three) control signal lines (for example, status signal lines) for notifying the CPU of the status state from the printer, and the printer for C
A control signal line (for example, a busy signal line) for notifying the PU of the busy state is included. As the parallel interface, one conforming to the Centronics parallel interface standard is known.

In the parallel data signal line in the parallel interface as described above, since the transmission direction is one direction from the CPU to the printer, data cannot be transmitted from the printer to the CPU. Therefore, when the printer cannot receive data, the printer asserts a busy signal (that is, activates it) and asserts a plurality of status signals to notify the CPU of the trouble content.

When the CPU wants to automatically detect the type of trouble in the printer, it checks the status signal from the printer. However, the types of troubles that can be identified from the status signal are out of paper, offline, machine error, etc.The types of troubles that can be identified are compared with the trouble contents that have become more diverse as the printers have become more sophisticated. It was extremely limited. For this reason, the CPU cannot automatically isolate printer troubles and take a flexible and appropriate response.

In order to deal with such a problem, for example, in the interface system disclosed in Japanese Patent Laid-Open No. 1-302453, the trouble content is notified by serial communication via a status signal line. .

In the printer BUSY control system disclosed in Japanese Patent Laid-Open No. 61-288224, the printer is notified of trouble content by controlling the length of time during which the busy signal is asserted. ing. In other words, the time length of the active (indicating that data cannot be received) busy signal is controlled according to the content of the trouble, and the busy signal is made inactive after a certain time has elapsed.

[0007]

However, in the one disclosed in Japanese Patent Laid-Open No. 1-302453, the serial data transmitting means for transmitting serial data to the connecting circuit portion of the printer and the connecting circuit portion of the CPU are provided. A serial data receiving means for receiving serial data must be provided for each, and it is extremely difficult to reflect it on the existing CPU and printer side.

Further, in the one disclosed in Japanese Patent Laid-Open No. 61-288224, since the active busy signal changes to inactive after a certain time elapses, the CPU changes the busy signal to inactive. After the change, the printer status cannot be investigated. In order to solve this, the printer side must hold information as to whether or not data can be received, so a memory for that is required.

It is usually easy to add a status signal line in order to increase the types of troubles that the CPU can identify. In this case, however, the number of signal lines increases and the connector size increases. Therefore, it is necessary to change the existing CPU and the connection circuit portion on the printer side. However, since these devices do not take measures to change the connection circuit portion, it is extremely difficult to increase the types of troubles that the existing CPU can identify.

According to the present invention, individual status lines can be used together without increasing the number of signal lines, and detailed trouble contents of the printer can be notified to the device in response to a request from the device for transferring data. An object is to provide an interface device.

[0011]

The present invention provides an interface device (30 in FIG. 1) provided between a printer (20 in FIG. 1) and a device (10 in FIG. 1) for transferring data to the printer. , If a strobe signal of a time longer than a predetermined time is received from the device that transfers the data while receiving a busy signal from the printer, a parallel error code indicating the reason why the device cannot receive the data. Is transmitted via a plurality of status signal lines (40 in FIG. 1).

[0012]

According to the present invention, the processing means is a device for transferring data during a period in which the printer outputs a busy signal indicating that the printer cannot receive data (for example, an upper central processing unit). When an active strobe signal is received for a time longer than a predetermined time, a plurality of status signals are sent to the central processing unit, each of which normally sends a parallel error code indicating the reason why data cannot be received. Send over the wire. As a result, the detailed error content of the printer is notified to the device that transfers the data without increasing the number of signal lines in response to the inquiry of the error content by the strobe signal.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the accompanying drawings of FIGS.

FIG. 1 shows the connection relationship of a parallel interface between a printer having the interface device of the present invention and a higher-level central processing unit (hereinafter referred to as CPU).

In the figure, the CPU 10 and the printer 20
Is a data line DATA, a strobe signal line STRB, a busy signal line BUSY, a plurality of status signal lines STA
T and ground line GND are connected. Then, the CPU 10 outputs the print data code to the data line DATA and the active strobe signal (negative logic) to the strobe signal line STRB to output the printer 2
Directs 0 to receive the print data code. Further, the printer 20 notifies the CPU 10 whether or not the data can be input, depending on the level of the busy signal line BUSY.

The printer 20 is provided with an interface device 30 for transmitting and receiving data and signals to and from the CPU 10. The interface device 30 operates during a period in which the printer 20 outputs an active busy signal. When the active strobe signal for a longer period than the predetermined period is received from the CPU 10, the processing means 4 for transmitting the error code indicating the reason why the data cannot be received to the CPU 10 via the plurality of status signal lines STAT.
Has 0.

In this embodiment, the signal on one strobe signal line STRB that is shorter than a preset time is the meaning of the data strobe signal for instructing the reception of the original print data code, and The length longer than the preset time is used as the meaning of the error strobe signal for inquiring the error content, and the strobe signal line is used in two meanings due to the difference in time length. Of course, the meaning of these strobe signals is predefined between the CPU 10 and the interface device 30. By defining the meaning of the strobe signal in this way, the processing means 40 in the interface device 30 can notify the CPU 10 of the detailed error content in response to the inquiry by the error strobe signal from the CPU 10.

Here, in addition to the conventional error contents such as paper shortage, offline and machine error, the detailed error contents include, for example, "paper jam", "specified paper is not set", printer error, etc. Includes error content associated with higher functionality. When the number of status signal lines is set to three in this embodiment, the error content can be represented by 3 bits.

For example, an error code Error content 000 Paper out 010 Offline 011 Machine error 101 Paper jam 110 It is possible to define that the specified paper is not set.

FIG. 2 shows a detailed block diagram of the processing means 40 in the interface device 30 shown in FIG. In the figure, the falling edge detector 41 detects the falling edge of the strobe signal, and the rising edge detector 42 detects the rising edge of the strobe signal. The timer 43 starts timing from the time when the falling edge is detected by the falling edge detection section 41, outputs this measured time value to the comparator 44, and stops the counting when the rising edge detection section 42 detects the rising edge. , Reset the time value.

Since the preset maximum data strobe signal time information of the data strobe signal from the maximum data strobe signal time setting unit 45 is input to the comparator 44, the comparator 44 is set to the setting unit 45. From the timer 43 is compared with the time from the timer 43. Where timer 4
When the time count value from 3 is less than or equal to the preset maximum data strobe signal time, the data input unit 46 is instructed to receive data, while when it exceeds the maximum data strobe signal time, The data input unit 46 is instructed to cancel the data reception, and the output unit 47 is notified that the maximum data strobe signal time has been exceeded.

A control signal from a printer control unit (not shown) provided in the printer 20 is input to the output unit 47. The printer control unit detects the printer state and outputs the busy state to the output unit 47.
Output to and at the same time detect the error content of the printer,
The detected error content is output to the output unit 47. Then, the output unit 47 outputs the busy signal and the status signal to the CPU 10 based on the input control signal. For example, when the notification that the maximum data strobe signal time has been exceeded is received from the comparator 44 and the busy signal on the busy signal line BUSY is active at the time of receiving the notification, An error code indicating the reason why data cannot be received is output on the status signal line STAT. When the strobe signal from the CPU 10 becomes inactive, the output of the error code is stopped.

Next, the process of inquiring about the error contents and notifying the error contents of this embodiment will be described with reference to FIG.

FIG. 3 is a timing chart showing the timing relationship between inquiry about error content and notification of error content. In the figure, (a) shows print data output from the CPU 10, (b) shows strobe signals (negative logic) output from the CPU 10, and (c) shows the printer 20.
Shows a busy signal output from the printer, and (d) shows a status signal output from the printer.

First, the maximum data strobe signal time T2 of the data strobe signal is negotiated between the CPU 10 and the printer 20. The result is held in the maximum data strobe signal time setting unit 45 in the interface device 30. Since the time length T1 of the data strobe signal sent by the CPU 10 is usually about several microseconds, the maximum data strobe signal time T
If 2 is set to about several milliseconds, the interface function of the existing printer will not be impaired.

The falling edge detection section 41 uses the strobe signal line ST.
When the falling edge of the strobe signal output to RB is detected, the timer 43 is started. When the timer 43 is started by the fall detection unit 41, the timer 43 starts counting time, and
Time is counted until the rising edge of the strobe signal is detected by the rising edge detection section 42, and when the rising edge of the strobe signal is detected, the time counting is stopped and the timed value is reset. This means that the time when the strobe signal is active is measured.

Here, as shown in FIG. 3B, time t1
When the strobe signal becomes active at, and becomes inactive at time t2, the timer 43 outputs "time t2-time t1 = time T1". In this case, this time T1 becomes equal to or less than the preset maximum data strobe signal time T2. And the data input section 4
6 is at time t3 as shown in FIG.
Since print data from the CPU 10 as shown in FIG. 3 is received, the output unit 47 outputs a busy signal that has changed from inactive to active at time t3 as shown in FIG. Become.

Next, as shown in FIG. 3 (d), at time t4,
When trouble occurs in the printer 10, the output unit 47 outputs a status signal changed from a ready state to an error state. It should be noted that this status signal has the same contents as the status notification as before.

On the other hand, in the CPU 10, the printer 2
If 0 indicates that data input is not possible by activating the busy signal, send the active strobe signal for a time longer than the time T1 of the active data strobe signal. As a result, the printer 20 is instructed to output an error code indicating the error content.

For example, as shown in FIG. 3B, time t5
Then, the strobe signal changed from inactive to active is output longer than the preset maximum data strobe signal time T2 (which also means that it is longer than the time T1).

In this way, when the strobe signal changes to active at time t5, the fall detector 41 detects the fall of the strobe signal and activates the timer 43. The activated timer 43 starts clocking and outputs the clocked value to the comparator 44. Then, the comparator 44 uses the timer 43.
From the maximum data strobe time setting unit 45
If it is determined that the maximum data strobe signal time T2 from the above is exceeded, the output unit 47 is notified of that fact.

Then, as shown in FIG. 3D, the output unit 47 outputs a detailed printer error code of the error content to the status signal line STAT instead of the conventional error content at time t6.

When the error code is output in this manner, the CPU 10 sends the active strobe signal at the time point t5, and even after the elapse of a time T3 longer than the maximum data strobe signal time T2 by a predetermined period. , It is confirmed that the busy signal line is still active, and the trouble content is detected by sampling the error code on the status signal STAT, and the strobe signal is detected at time t7 as shown in FIG. 3 (b). From active to inactive.

As described above, according to this embodiment, C
When the PU 10 receives the active busy signal and further receives the notification of the error, the PU 10 inquires of the printer, that is, the interface device about the error content, and the detailed information from the interface device responding to this inquiry is sent. The error code indicating the error content can be received and the error content can be investigated.

Although the interface device 30 is provided on the printer 20 side in the above embodiment, the invention is not limited to this, and the interface device 30 may be replaced by a C
It may be provided anywhere between the PU 10 and the printer 20.

[0036]

As described above, according to the present invention, a device for transferring data while the processing means is outputting a busy signal indicating that the printer cannot receive data. When a strobe signal is received for a time longer than a predetermined time from, a parallel error code indicating the reason why data cannot be received is sent to the device via multiple status signal lines that normally send individual statuses. Therefore, the device that transfers the data is notified of the detailed error content of the printer in response to the inquiry about the error content by the strobe signal. Therefore, without increasing the number of signal lines,
A device that transfers data has an advantage of being able to receive and investigate detailed error content when it is desired to investigate the error content.

[Brief description of drawings]

FIG. 1 is a diagram showing a connection relationship of a parallel interface between a printer having an interface device according to the present invention and a central processing unit.

FIG. 2 is a detailed block diagram of a processing unit 40 in the interface device 30 shown in FIG.

FIG. 3 is a timing chart showing the processing operation of this embodiment.

[Explanation of symbols]

10 ... Central processing unit, 20 ... Printer, 30 ... Interface device, 40 ... Processing means, 41 ... Fall detection unit, 4
2 ... Rise detection unit, 43 ... Timer, 44 ... Comparator, 45
... maximum data strobe signal time setting unit, 46 ... data input unit, 47 ... output unit.

Claims (1)

[Claims] 1. An interface device provided between a printer and a device for transferring data to the printer, the time being longer than a predetermined time from the device for transferring the data while receiving a busy signal from the printer. When the strobe signal is received, the interface device is provided with a processing means for transmitting a parallel error code indicating a reason why the data cannot be received to the device via a plurality of status signal lines.