JPH10187378A - Printing device and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of the repetition of a buffer full error resulted from the transmission of a buffer full message. SOLUTION: Increasing data amounts to a transmission buffer in a prescribed time are counted as a counter A, and decreasing data amounts are counted in the same way as a counter B. The increasing and decreasing speed M of data is calculated from the value (S602), and when the data amounts are larger than a threshold value, and the increasing and decreasing speed indicates increase twice in a row (S603-S605-YES), it is judged that the transmission buffer is full, and the result message is outputted (S606). Otherwise, it is judged that the transmission buffer is not full, and an already outputted full message is taken out (S610). Afterwards, the counters A and B are reset, and the measurement is repeated. Thus, the useless buffer full message can not be outputted by checking the increase tendency of the data amounts without simply checking the buffer full state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a printing apparatus capable of transmitting data to a host computer or the like and performing bidirectional communication, and a control method therefor.

[0002]

2. Description of the Related Art In a conventional printing apparatus, one-way data transmission is overwhelmingly in communication with other devices such as a host computer, and two-way data transmission is very little. Particularly, almost no data transmission from the printing apparatus to the host computer is performed, and most of the transmission of print data and control data from the host computer to the printing apparatus is performed.

However, status information of the printing apparatus is frequently transmitted to the host computer to inform a user operating the host computer of the status of the printing apparatus,
The remote control of the printing apparatus and the like can be performed from the host computer, and the ratio of the data amount of data communication with various device devices surrounding the printing apparatus has changed.

In order to make the printing apparatus cope well with the above situation, the transmission buffer full state is indicated when transmission data from the printing apparatus is accumulated in the transmission buffer and becomes buffer full. A message is displayed on the panel and the status is sent to the host computer to notify the user.
That is, whether or not to notify the user is determined based on whether or not the transmission buffer of the printing apparatus is full.

[0005]

However, in the printing apparatus shown in the above conventional example, for example, the speed at which the host computer processes data received from the printing apparatus is faster than the speed at which the printing apparatus generates data to be transmitted. If the speed is high, the transmission buffer of the printing apparatus tends to be full, and once the state is full, the following problem may occur.

[0006] When the transmission buffer of the printing apparatus is full, the transmission buffer of the printing apparatus becomes empty because the host computer processes the received data. Then, in the printing apparatus, a message for notifying the host of the above-mentioned transmission buffer full state is written in the transmission buffer, so that the transmission buffer becomes full again. At that time, a buffer full state was generated when the message was written, because the message of the transmission buffer full was generated simply based on whether or not the writing to the transmission buffer could be performed.
When a message about the buffer full is written to the transmission buffer, it becomes impossible to write to the transmission buffer again. Thus, once the buffer full state occurs, the state may occur repeatedly. As described above, the transmission buffer goes back and forth between the full state and the non-full state, and a message of the transmission buffer full is generated many times, and unnecessary processing is performed on both the printing apparatus side and the host computer side. There was a problem of doing.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above-mentioned prior art, and is not a speed at which the host device processes data received from the printing device, but a speed at which the printing device generates data to be transmitted to the host device. It is an object of the present invention to provide a printing apparatus which can prevent a buffer full state from being repeatedly generated even when the printing is fast, and can smoothly execute a printing process without performing useless communication and processing, and a control method thereof.

[0008]

Means for Solving the Problems To achieve the above object, the present invention has a configuration as proposed by the present invention. That is, a printing device that transmits data such as status to the host device, a transmission buffer in which data to be transmitted to the host device is written, a writing unit that writes transmission data to the transmission buffer, First counting means for counting the amount of data written to the transmission buffer;
A second counting means for counting the amount of data transmitted from the transmission buffer to the host device within the predetermined time; and a data amount in the transmission buffer based on a result of the first and second counting means. Determination means for determining the transition of, when the determination means determines that the transmission buffer has shifted to a buffer full state, output means for outputting a message of transmission buffer full, and the determination means, Means for canceling the already output transmission buffer full message when it is determined that the transmission buffer has not transitioned to the buffer full state.

Alternatively, there is provided a method of controlling a printing apparatus for transmitting data such as status to a host apparatus,
A writing step of writing transmission data to a transmission buffer into which data to be transmitted to the host device is written; a first counting step of counting the amount of data written to the transmission buffer within a predetermined time; To count the amount of data transmitted from the host device to the host device
Counting step, a judgment step of judging a change in the amount of data in the transmission buffer from the results of the first counting step and the second counting step, and the transmission step shifts to a buffer full state by the judgment step. When it is determined that the transmission buffer is full, the output step of outputting a message indicating that the transmission buffer is full, and when the determination step determines that the transmission buffer has not transitioned to the buffer full state, the message is already output. Canceling the transmission buffer full message.

[0010] Alternatively, a writing step of writing transmission data to a transmission buffer for storing a control program of a printing apparatus for transmitting data such as status to the host apparatus, wherein the transmission buffer stores data to be transmitted to the host apparatus. And a code of a first counting step for counting the amount of data written to the transmission buffer within a predetermined time, and a code for counting the amount of data transmitted from the transmission buffer to the host device within the predetermined time. 2, the code of the counting step, the first counting step and the second
A code of a judging step of judging a change in the amount of data in the transmission buffer from the result of the counting step; and, if the judging step judges that the transmission buffer has shifted to a buffer full state, the transmission buffer By the code of the output step of outputting a full message and the determination step,
A code for canceling the already output transmission buffer full message when it is determined that the transmission buffer has not transitioned to the buffer full state.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of the present invention, a printing system in which an external device and a printer are connected will be described.

FIG. 1 shows the configuration of a printing system according to the present embodiment. In FIG. 1, an external device 101 such as a host computer is connected to a laser beam printer 102 to which the present embodiment is applied, and transmits print data and control data to the printer 102 and receives data from the printer 102. To process. Printer engine unit 105
Forms a latent image on a photosensitive drum by a well-known electrophotographic process based on image data (binary or multi-valued data), transfers the latent image to paper, fixes it, and performs printing. The printer controller 103 includes a printer engine 105.
, And code data (ESC code, various PDLs) sent from an external device 101 such as a host computer.
), And generates page information including dot data based on the code data.
, The image data is transmitted by a predetermined interface means. The panel unit 104 performs an interface with a user (operator). By operating the panel unit 104, the user can instruct the printer 102 to perform a predetermined operation. The printer 10
A transmission buffer 1031 for temporarily storing data transmitted from the second device to the external device 101 is included in the printer controller unit 103.

FIG. 2 is a sectional view schematically showing a printer mechanism according to the present embodiment. In FIG.
An operation panel 202 is provided on 01. The operation panel 202 includes switches for operation, an LED display, and an LCD display. This is a physical aspect of the panel unit 104 shown in FIG. The control board storage unit 203 stores a printer engine unit 105 that controls a printing process of the printer, and a print controller unit 103 that controls the entire printer and analyzes data from a host computer and converts the data into image data. The paper cassette 210 has a mechanism for electrically detecting a paper size by a partition plate (not shown). The cassette paper feed clutch 211 is a cam that separates only the top sheet of the paper placed on the paper cassette 210 and transports the separated paper to a paper feed roller 212 by a driving unit (not shown). It rotates intermittently for each sheet of paper, and feeds one sheet of paper corresponding to one rotation. Resist shutter 2
14 stops the paper feeding by pressing the paper. The paper feed roller 212 conveys the leading edge of the paper to the registration shutter 214. The manual paper feed clutch 215 is configured to hold the leading end of the paper placed on the manual tray 219 with the registration shutter 2.
To 14. With the above configuration, paper can be selectively fed from the paper cassette 210 and the manual feed tray 219.

The printer engine unit 105 communicates with the printer controller unit 103 according to a predetermined communication protocol, and in accordance with an instruction from the print controller unit 103, the cassette 210 or the manual tray 21.
9, the sheet feeding means is determined, and the sheet feeding is started as described above in accordance with the print start instruction.
Conveyed to 4. The cartridge 204 includes the photosensitive drum 2
05 and a toner holding unit (not shown). When the sheet is conveyed to the registration shutter 214, a laser beam emitted from a semiconductor laser (not shown) that is turned on and off by a laser driver 206 according to image data sent from the printer controller 103 is rotated by a rotating polygon mirror 207. Reflected mirror 2 scanned in main scanning direction
The image is guided to the photosensitive drum 205 via the imaging device 08 to form an image, and is scanned in the main scanning direction to form a latent image on a main scanning line.
The resist shutter 2 is synchronized with the reflection of the laser beam.
14 is driven upward to synchronize the conveyance of the sheet with the sub-scan of the laser beam. The beam detector 209 arranged at the scanning start position of the laser beam generates a synchronization signal for determining the timing of writing an image for main scanning by detecting the laser beam, and sends the synchronization signal to the printer controller 103. The photosensitive drum 205 is driven to rotate by a motor (not shown), is developed as a toner image by a developing unit 220, and is transferred onto a sheet conveyed by a conveying roller 213. The paper on which the toner image has been transferred
Heat fixing of the toner image is performed by the fixing roller 216,
The sheet is discharged to a sheet discharge tray of the printer housing 201 by a sheet discharge roller 218 via a transport roller 217.

FIG. 3 is a block diagram of the printer controller 103 according to the present embodiment. In the figure, a panel interface unit 301 receives various settings and instructions from an operator from the panel unit 104 by data communication with the panel unit 104. Host interface unit 30
Reference numeral 2 denotes an input / output unit for signals with the external device 101 such as a host computer, and has an input / output buffer. The engine interface unit 306 includes the printer engine unit 105
And an input / output unit for transmitting a data signal from an output buffer register (not shown) and controlling communication with the printer engine 105. Image data generator 3
An image data generating unit 03 generates bitmap data for actual printing based on control code data sent from the external device 101. The image memory 305
Stores image data. The CPU 309 controls the entire printer controller 103. ROM 304 is
The control code (program) executed by the CPU 309 is stored. The RAM 307 is a temporary area used by the CPU. This also includes the transmission buffer 1031. The program code stored in the RAM 307 is CP
The program may be executed by U309, in which case the program is supplied from a secondary storage 312 described later. E
EPROM 310 is an electrically erasable non-volatile memory. The DMA control unit 308 transfers the bits and the map data in the image memory to the engine interface unit 306 according to an instruction from the CPU 309. The secondary storage unit 312 is a fixed device such as a hard disk, or a removable device such as a floppy disk or a magneto-optical disk. The secondary storage unit 312 includes a file of a program executed by the CPU 309, data to be printed, and data defined separately. Stores data files such as form data. System bus 311 includes an address bus and a data bus. A panel interface 301, a host interface 302, an image data generator 303,
ROM 304, image memory 305, engine interface 306, RAM 307, DMA controller 308,
The CPU 309 and the EEPROM 310 are each connected to the system bus 311 and can access all functional units on the system bus 311.

The control code for controlling the CPU 304 is composed of an OS for performing time-division control in units of load modules called tasks by a system clock (not shown) and a plurality of load modules (tasks) operating in units of functions. And

FIG. 4, FIG. 5, and FIG. 6 are flowcharts showing the processing procedure executed by the printing apparatus of the present embodiment. FIG. 4 shows an example of a procedure for writing transmission data to a transmission buffer.

In FIG. 4, at step S401,
If there is a status request from the host computer,
It is determined whether an event for transmitting data to the host computer has occurred in the printing apparatus. When an event occurs, transmission data to be written to the transmission buffer is created (step S402), and the created transmission data is written to the transmission buffer 1031 by the required number of bytes (step S403). If there is no data to be transmitted such as a state change, in step S409, another task is started once, and after waiting for a predetermined time, the next event is waited.

From the result of writing to the transmission buffer in step S403, the number of bytes X written this time is
It is added to the data amount A written during the fixed time T (step S404). In step S403, it is determined whether or not the data has been written a little (step S405). If the data can be written even a little, the timeout period is reset (step S406). Then, the next write position and the number of free bytes in the transmission buffer are updated (step S407). Step S40
6 is a predetermined length of time counted in step S609 of the timer task process (a task different from FIG. 4) shown in FIG.
This is different from the time T when the transmission data amount is measured.

In step S408, it is determined whether or not the writing of the status that has occurred this time into the transmission buffer has been completed, and if not completed, another task is started once and waits for a predetermined time (step S409 ″). Returning, the remaining transmission data is written into the transmission buffer again, and the same processing is repeated until all the writing is completed.

On the other hand, if even one byte cannot be written in step S405, reference is made to the above-mentioned timeout time (step S410). If the specified timeout time has not been reached (step S411),
Start another task once and wait for a certain time (step S4
09 '). Thereafter, the flow returns to step S403 to write the remaining transmission data into the transmission buffer again, and repeats the same processing until all the writing is completed. Usually,
In many cases, writing can be performed once, but when a large amount of data is to be transmitted, writing is repeated until writing of all transmission data is completed by this routine.

If the time-out period has been reached in step S411, the data to be transmitted is discarded (step S412), and the process ends.

Unless a timeout occurs, the process ends when all processes are completed, and waits for the next event. While writing the transmission data generated as described above to the transmission buffer, the amount of data written to the transmission buffer is obtained. FIG.
As will be described, since the data amount counter A is reset every time T, the write data amount obtained by the procedure of FIG.

Next, FIG. 5 shows an example of a procedure for detecting the transmission speed when the content written in the transmission buffer is actually transmitted to the external device.

The transmission of the data stored in the transmission buffer is performed according to the standard of each interface by task polling and occurrence of an event due to an interrupt (step S501). Next, based on the transmission result from the transmission buffer in step S501, the number of bytes Y transmitted this time is added to the data amount B transmitted within the fixed time T, and the total data transmitted since the previous reset of the counter B is added. The amount B is obtained (step S502), and the process ends. In FIG. 5, as in FIG. 4, the counter B is reset every predetermined time T, so the value indicated by the counter B indicates the amount of data transmitted from the printer within the predetermined time T.

Next, FIG. 6 shows an example of a procedure for performing time management such as a rate of increase and decrease of data in the transmission buffer and a timeout time. In FIG. 6, for the sake of simplicity, the description will be made by limiting the sampling of the data increase / decrease rate in the transmission buffer to M and M '. Normally, the processing in FIG. 6 starts when the timer in which the predetermined time T is set by the timer task expires, and when the processing in FIG. 6 ends, the time T is set to the timer again and the timer task is started. You. That is, the processing in FIG. 6 is executed by activating the task at regular intervals.

When the timer set for time T expires,
When the task is started, the increase / decrease speed M of the data in the transmission buffer calculated last time is stored in M ′ in step S601, and is used later when it is referred to as the previous increase / decrease speed. As described with reference to the flow charts of FIGS. 4 and 5, the data write amount A within the predetermined time T calculated at the time of writing to the transmission buffer and transmission from the transmission buffer.
(In) and the data transmission amount B (out), the data increase / decrease speed M that has entered / exited the transmission buffer during the predetermined time T is (A
-B) / T (Step S602). Time T
Is an interval at which the counters A and B are reset by executing the procedure of FIG. 6, that is, one sampling period.

In the present embodiment, it is determined whether the transition to the transmission buffer full state has actually occurred, or whether the state has changed between the buffer full state and the other state near the buffer full state. It is intended to prevent generation of unnecessary transmission data. Therefore, as shown in FIG. 7, a threshold value is provided in the transmission buffer, and the processing is performed separately in two cases: a case where the data amount is equal to or less than the threshold value (a) and a case where the data amount exceeds the threshold value (b).

If the data amount is above the threshold and M> 0,
If M ′> 0, that is, if the data in the transmission buffer is larger than the threshold value and continues to increase over two sampling periods (step S603-YES,
Step S604-YES, step S605-YE
S), a message indicating that the transmission buffer is full is displayed and the state is changed (step S606). That is, the event of the transmission buffer full occurs with this as a trigger, and the processing of FIG. 4 is performed to generate transmission data.

In other cases, that is, although the data amount is less than the threshold value or exceeds the threshold value,
If the data volume does not continue to increase over the sampling period, it is determined that the change in the data volume in the transmission buffer is not going to increase in the same direction, and a message indicating that the transmission buffer is full is displayed. Absent. If a message indicating that the transmission buffer is full is already displayed, the message is deleted (step S610).

Thereafter, a wait is performed for a predetermined time (step S6).
07), the values of the counters A and B are reset (step S608). In the present embodiment, the time T from this reset to the next reset is set as one sampling period. In step S609, if the transmission is not possible, the timeout time is counted up and the task waits for a time.

According to the procedure described above, the printing apparatus of the present embodiment does not simply detect buffer full based on the amount of data in the transmission buffer, but measures the rate of increase or decrease of transmission data within a predetermined time, and Since the transmission buffer full state is determined based on the measured increase / decrease speed, the occurrence of the buffer full state caused by storing the message indicating the buffer full state in the transmission buffer can be prevented. Therefore, unnecessary error notification and error processing are not required. For this reason, it is possible to smoothly execute the original print processing of the printing apparatus. Further, since unnecessary messages are not issued, the host computer does not need to receive useless data, so that both the printing apparatus and the host computer can increase the efficiency.

In the above-described embodiment, the sampling of the increase / decrease speed is performed in two sampling periods.
A determination may be made as to whether or not to display a transmission buffer full message by sampling in three or more sampling periods. For example, when the increase / decrease rate is sampled in five sampling periods, a condition may be provided that a message indicating that the transmission buffer is full is displayed when all the latest increase / decrease rates exceed a certain threshold. Further, a condition may be provided that a message indicating that the transmission buffer is full is displayed only when both conditions are satisfied by combining these. In this way, accurate sampling can be performed by monitoring the increase / decrease of the transmission buffer by increasing the sampling to some extent.

Further, in the above-described embodiment, the sampling time is set as the time required for one task activation. However, a counter for managing the number of task activations is provided. For example, the counter is counted up in step S609. The time until reaching a certain value may be used as the sampling time. It is preferable to determine the optimum number of times for these sampling times by considering how long it takes for the task to start and what proportion of the transmission data is generated.

[0035]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer (or CPU) of the system or apparatus.
Or MPU) reads and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) Performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, The case where the CPU of the function expansion board or the function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing.

[0041]

As described above, according to the printing apparatus and the control method thereof according to the present invention, the speed at which the printing apparatus generates data to be transmitted to the host apparatus is higher than the speed at which the host apparatus processes data received from the printing apparatus. Even if the speed is faster, the buffer full message is not repeatedly generated and unnecessary transmission is not performed, so that the printing process inherent in the printing apparatus can be smoothly performed. Further, since unnecessary messages are not issued, the host computer does not need to receive useless data, so that both the printing apparatus and the host computer can increase the efficiency.

[0042]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a system including a printer to which the present invention is applied.

FIG. 2 is a schematic sectional view of a printer to which the present invention is applied.

FIG. 3 is a block diagram illustrating an electrical configuration of a printer controller to which the present invention is applied.

FIG. 4 is a flowchart showing an example of a method of writing to a transmission buffer and a method of calculating a writing speed corresponding to the free space of the transmission buffer in the embodiment.

FIG. 5 is a flowchart illustrating an example of a transmission speed calculation method when data is transmitted from a transmission buffer to an external device in the embodiment.

FIG. 6 is a flowchart illustrating an example of time management by a timer task, a data increase / decrease rate calculation method, and a message display in the embodiment.

FIG. 7 is a diagram illustrating a relationship between a data amount in a transmission buffer and a threshold in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 External apparatus 102 Printer 103 Printer controller 1031 Transmission buffer 104 Panel part 105 Printer engine

Claims (11)

[Claims] 1. A printing device for transmitting data such as status to a host device, a transmission buffer in which data to be transmitted to the host device is written, writing means for writing the transmission data in the transmission buffer, and a predetermined time. A first counting unit that counts an amount of data written to the transmission buffer within the second buffer; a second counting unit that counts an amount of data transmitted from the transmission buffer to the host device within the predetermined time; Determining means for determining a change in the amount of data in the transmission buffer based on the results of the first counting means and the second counting means; and the determining means determines that the transmission buffer has shifted to the buffer full state. An output unit that outputs a message indicating that the transmission buffer is full, and the determining unit shifts the transmission buffer to a buffer full state. And when it is determined not to already printing apparatus characterized by comprising a means for canceling the transmit buffer full message output. 2. A measuring means for measuring a timeout time, a resetting means for resetting a timeout time when data is written to the transmission buffer, and a timeout time when data cannot be written to the transmission buffer by the writing means. A second determining means for determining whether a timeout has occurred with reference to the above. If the second determining means determines that a timeout has occurred, the writing means writes data to be written to the transmission buffer. 2. The printing apparatus according to claim 1, further comprising a timeout processing unit for discarding. 3. The apparatus further comprises detecting means for detecting that all of the transmission data which the writing means has attempted to write to the transmission buffer has not been written, and when not all of the transmission data can be written to the transmission buffer, the writing means comprises 3. The printing apparatus according to claim 1, wherein writing is repeatedly performed until all remaining transmission data can be written. 4. The apparatus according to claim 1, further comprising: reset means for resetting a result counted by said first and second counting means at predetermined time intervals, wherein said first and second counting means perform data writing to a transmission buffer. 4. The printing apparatus according to claim 1, wherein when the resetting is performed, a data write amount after the reset by the reset unit is performed is added. 5. The transmission buffer, wherein the determining means counts an increase amount of data in the transmission buffer within a predetermined time, which is counted by the first counting means, and is counted by the second counting means. Having a calculating means for calculating an increase / decrease rate of the data in the transmission buffer based on the decrease amount of the data in the transmission buffer within a predetermined time, wherein the data amount in the transmission buffer is equal to or more than a predetermined amount, and When the increase / decrease rate calculated over a predetermined time indicates an increase in the data amount, it is determined that the state has shifted to the buffer full state, and otherwise, it is determined that the state has not shifted to the buffer full state. The printing device according to any one of claims 1 to 4, wherein 6. A method for controlling a printing apparatus for transmitting data such as status to a host device, comprising: a writing step of writing transmission data to a transmission buffer in which data to be transmitted to the host device is written; A first counting step of counting the amount of data written to the transmission buffer; a second counting step of counting the amount of data transmitted from the transmission buffer to the host device within the predetermined time; A determining step of determining a change in the amount of data in the transmission buffer from a result of the counting step and the second counting step; and, if the determining step determines that the transmission buffer has shifted to a buffer full state, An output step of outputting a message indicating that the transmission buffer is full; and the determination step determines that the transmission buffer has not transitioned to the buffer full state. Canceling the already output message of the transmission buffer full when it is determined that the printing is complete. 7. A measuring step for measuring a timeout time, a resetting step for resetting a timeout time when data is written to the transmission buffer, and a timeout time when data cannot be written to the transmission buffer by the writing step. A second determining step of determining whether or not a timeout has occurred, and if the second determining step determines that a timeout has occurred, the writing step writes the data to be written into the transmission buffer. 7. The method according to claim 6, further comprising a timeout processing step of discarding. 8. The apparatus according to claim 1, further comprising a detecting step of detecting that all of the transmission data to be written by the writing step has not been written to the transmission buffer. 8. The method according to claim 6, wherein writing is repeatedly performed until all remaining transmission data can be written. 9. The method according to claim 1, further comprising a resetting step of resetting the results counted in said first and second counting steps at predetermined time intervals, wherein said first and second counting steps include writing data to a transmission buffer. 9. The method according to claim 6, further comprising adding a data write amount after the resetting is performed in the resetting step. 10. The transmission buffer, wherein the determination step includes the step of counting an amount of increase in data in the transmission buffer within a predetermined time, which is counted by the first counting step, and a step of counting by the second counting step. Having a calculation step of calculating the rate of increase or decrease of the data in the transmission buffer based on the decrease amount of the data in the transmission buffer within a predetermined time, wherein the data amount in the transmission buffer is not less than a predetermined amount, When the increase / decrease rate calculated over a predetermined time indicates an increase in the data amount, it is determined that the state has shifted to the buffer full state, and otherwise, it is determined that the state has not shifted to the buffer full state. The control method for a printing apparatus according to any one of claims 6 to 9, wherein: 11. A computer-readable memory storing a control program of a printing device for transmitting data such as status to a host device, wherein the transmission data is written to a transmission buffer in which data to be transmitted to the host device is written. A code for a first counting step for counting the amount of data written to the transmission buffer within a predetermined time; and a code for counting the amount of data transmitted from the transmission buffer to the host device within the predetermined time. 2, a code of a counting step, a code of a determining step of determining a change in the amount of data in the transmission buffer based on the results of the first counting step and the second counting step, If it is determined that the state has shifted to the buffer full state, the output step of outputting a transmission buffer full message And a code for a step of canceling the already output transmission buffer full message when it is determined by the determination step that the transmission buffer has not transitioned to the buffer full state. Computer readable memory.