JP2000231457A - Data transfer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the transfer speed of data from a host device to an external device by selecting a standby time matching the external device according to the relation between apparent transfer speeds and standby times. SOLUTION: A host computer 1 is equipped with a high-speed processor and the data transfer speed of a printer driver 6 is very fast, so a printer 3 possibly causes an underline or data absent phenomenon in this state. For the purpose, a port driver 7 adjusts the transfer rate of the printer driver 6. Namely, when data transfer from the host computer 1 is carried out at a data transfer speed much faster than the reception speed that the printer requires, the port driver 7 when transferring data passed from the printer driver 6 to the printer 3, byte by byte, provides a certain standby time each time one byte is transferred. Thus, the transfer of the data is delayed to make the apparent transfer speed slow on the whole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a data transfer system which optimizes a transfer speed when data is transferred from a host device to an external device.

[0002]

2. Description of the Related Art For example, when transferring print data from a personal computer to a printer, the personal computer and the printer are connected by a predetermined interface cable. A printer driver is installed in the personal computer, and transfers print data to the printer at a predetermined speed. The printer temporarily stores the print data in the printer buffer, and when the print data becomes full, requests the printer driver to temporarily stop the transfer.

When printing progresses and a printer buffer becomes empty, data is transferred again from the printer driver. When data is transferred from the host device to various external devices as well as the printing control of the printer, such a procedure is generally controlled.

[0004]

However, the above-mentioned prior art has the following problems to be solved.
For example, consider a case in which a personal computer is a host device and print data is transferred to a printer. 2. Description of the Related Art In recent personal computers, the processing speed of a CPU (central processing unit) has been remarkably improved. Therefore, CPU
In many cases, the data transfer rate is significantly different due to the performance difference. The printer is designed in consideration of the processing speed of the existing CPU, and when a new CPU with a high processing speed appears, the operation speed difference may exceed an allowable range.

In consideration of the printing speed and printing quality of the printer engine, the printer need not receive data at a speed higher than a predetermined speed. Rather, when data is transferred to the printer at a high speed, a load is applied to the processor of the printer for data transmission and reception, and there is a possibility that a failure such as data loss or underrun may occur as described later. As the arithmetic processing speed of the processor increases, the data transfer speed of the printer driver also increases. Therefore, with such advanced personal computers,
There is a need to develop a method for normally controlling a conventional printer. These problems also occur when transferring data from the host device to various external devices.

[0006]

The present invention employs the following structure to solve the above problems. <Structure 1> Consisting of a host device and an external device that receives data from the host device, the host device includes a transfer speed adjustment unit that adjusts the transfer speed of the data, and the transfer speed adjustment unit that has a unit amount. A wait processing unit for performing control so as to wait for transfer for a predetermined standby time every time data is transferred, wherein the transfer speed adjusting unit is configured to arbitrarily wait a predetermined amount of dummy data before transferring the data. A data transfer system which measures an apparent transfer speed when transferring data by time, and selects the standby time suitable for the external device from the relationship between the apparent transfer speed and the standby time.

<Structure 2> In the data transfer system described in Structure 1, the transfer speed adjusting section measures an apparent transfer speed when a predetermined amount of dummy data is transferred at different standby times. A data transfer system, wherein a change in an apparent transfer speed is obtained, and the standby time suitable for the external device is selected.

<Structure 3> In the data transfer system according to Structure 1 or 2, the transfer rate adjusting section measures an apparent transfer rate when a predetermined amount of dummy data is transferred during a selected standby time. A data transfer system that detects an error from a target data transfer speed and corrects the standby time.

<Structure 4> In the data transfer system according to Structure 1, the transfer rate adjusting unit measures an apparent transfer rate by using a timer provided on an external device side. Transfer system.

<Structure 5> In the data transfer system according to Structure 1, the transfer rate adjusting unit checks whether or not data loss has occurred when a predetermined amount of dummy data has been transferred for a selected standby time. A data transfer system characterized by partially adjusting the standby time when data loss occurs.

<Structure 6> Consisting of a host device and an external device for receiving data from the host device, the external device includes a reception speed measuring unit for measuring the reception speed of the data, The reception speed is compared with the optimum reception speed, and the time for enabling the busy signal for suppressing the data transmission by the host device every time a predetermined amount of data is received is set so that the data reception speed approaches the optimum reception speed. A data transfer system, comprising: a reception speed adjustment unit for adjusting.

<Structure 7> In the data transfer system according to structure 1 or 5, the external device is provided with a direct memory access controller for automatically receiving data from the host device, and the reception speed adjusting unit of the external device is
A data transfer system, wherein a waiting time is inserted every time the direct memory access controller receives an amount of data that can be received collectively.

<Structure 8> In the data transfer system according to Structure 1, when data is transferred from the host device to a plurality of external devices, the transfer speed adjusting unit transmits the data to the plurality of external devices simultaneously. A data transfer system which measures an apparent transfer speed and reduces the standby time so that the transfer speed approaches a target transfer speed.

<Configuration 9> In the data transfer system according to Configuration 8, when the number of external devices connected to the host device and simultaneously transferring data increases or decreases, an apparent data transfer rate to each external device is monitored. A data transfer system, wherein when the apparent data transfer rate changes, the standby time is reduced so that the transfer rate approaches a target transfer rate.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. <Specific Example> FIG. 1 is a block diagram showing a system of a specific example 1. The present invention can be applied to a case where data is transferred from a host device to various external devices. Here, a case where data is transferred from the host computer 1 to the printer 3 will be described as an example.

In FIG. 1, a printer 3 is connected to a host computer 1 via a bidirectional interface 2. This interface is IEEE1284
(Institute of Electrical and Electronic Engineer
This is a parallel interface standardized in s).
The host computer 1 is provided with an application (AP) 4 for generating data for printing, an operating system (OS) 5, a printer driver 6, a port driver 7, and an IEEE1284 output unit 8.

The printer 3 is a conventionally well-known printing device such as an electrophotographic printer or an ink jet printer. The port driver 7, as shown in this figure,
It comprises an I / F processing unit 11, a data transfer unit 12, a transfer speed adjustment unit 13, a timer 14, a counter generation unit 15, dummy data 16, a loop counter 17, and a wait processing unit 18.

In this system, the host computer 1
Has a high-speed processor, and the data transfer speed of the printer driver 6 is extremely high. Therefore, there is a possibility that the printer 3 may cause an underrun, missing data, or the like. Thus, in the invention of this specific example, the port driver 7 has a function of adjusting the transfer speed of the printer driver 6. The output of the printer driver 6 is sent to the I / F processing unit 1
1 and the data transfer unit 12 and are sent to the IEEE1284 output unit 8. The transfer rate adjusting unit 13 shown in FIG.
This section has a function of receiving a parameter indicating the data transfer rate of the host computer 1 from the processing section 11 and setting the adjusted transfer rate in the data transfer section 12. The data transfer unit 12 has a role of transferring print data input from the I / F processing unit 11 to the printer 3 via the IEEE1284 output unit 8.

Before describing the port driver 7 in detail, a failure that occurs in the printer 3 due to a difference in transfer speed will first be specifically described. FIG. 2 is a diagram illustrating a difference in transfer speed depending on the performance of a PC (personal computer). FIG. 5A shows that, for example, the data transfer rate is 6 per second.
00 KB host computer 1 to printer 3
(Here, a case where data is transferred to a laser printer) is shown. The operating clock of the processor in this case is 100 MHz per second. FIG. 3B shows a case where data is transferred from the host computer 1 having a data transfer speed of 1 megabyte per second to the printer 3. The operating clock of the processor is 100 MHz per second. (A)
Uses a PCI bus with 32-bit processing, and (b)
The difference is that the processor uses a VL bus for bit processing.

FIG. 2C shows an example of a 16-bit processor having a data transfer rate of 300 kilobytes per second. In this case, the operating clock of the processor is 66 MHz.
z. Also, (d) shows an example in which a 16-bit processor has a data transfer rate of 400 kilobytes per second. This processor has an operation clock of 66 MHz.
z. Each bus uses a VL bus.

Recently, processors having an operation clock of 200 MHz to 400 MHz have appeared. For example, it is assumed that a user connects personal computers having various performances to the same printer 3 as shown in this figure, or a print request is made from various personal computers through a network. As described above, when the frequency of the operation clock of the processor is extremely high, the printer driver operates at high speed, and the following load is applied to the printer 3.

FIG. 3 shows a printer operation time chart when the transfer speed is appropriate. A printer normally receives print data, performs an analysis process on the print data, and performs printing while controlling a printer engine. Therefore, as shown in this figure, it is preferable that processes such as reception, analysis, and printing are alternately and regularly repeated.

FIG. 4 is a time chart showing the operation of the printer when the data transfer speed is inappropriate. Usually, in a printer, reception processing has priority over analysis processing. That is,
If data is received during data analysis, the receiving process is given priority. In addition, the print processing is given priority over the analysis processing. This is because the driving of the print head, the spacing of the printing paper, and the like must be controlled at a constant speed without delay.

However, if the host receives the next data before the print data is received and the analysis process is started, for example, as shown by the arrow A in FIG. Will be done. Therefore, the analysis processing is postponed to the reception processing, and the printing timing is delayed by the time D. When the interruption due to such reception is repeated, the printing process is gradually delayed as shown in the figure. Here, when the delay reaches time 3D, an overrun occurs.

That is, the printing speed is constant, and the data must be analyzed and supplied to the printer engine in time. However, if there is a delay in the analysis processing, data cannot be supplied to the printer engine in time. Therefore, printing of a blank sheet is performed halfway without supply of print data. Such a problem occurs when data is transferred from the host computer at a data transfer speed much higher than the reception speed required by the printer. Therefore, in this specific example, the port driver 7 shown in FIG.
When transferring one byte at a time to the printer 3, a fixed waiting time is inserted every time one byte is transferred. By waiting for data transfer in this way, the apparent transfer speed as a whole is reduced. In this way, the data transfer speed is optimized. In another specific example, the printer transfers a busy signal for suppressing data transfer to reduce the apparent transfer speed.

The data transfer speed cannot be uniquely calculated only by the arithmetic processing speed of the processor of the host computer 1. The performance of the internal circuit of the host computer, the performance of the interface, the reception speed of the printer 3, etc.
Varies by various factors. Therefore, in this specific example, the transfer speed adjusting unit 13 is provided in the port driver 7 shown in FIG. 1, and the dummy data 16 is actually transferred to the printer 3 before the start of the print data transfer, and a predetermined standby time is set. Measure the transfer speed when you do. According to this result,
A standby time for optimizing an apparent transfer speed is calculated. The standby time is set in the loop counter 17 shown in FIG. The wait processing unit 18 controls the data transfer unit 12 to wait for data transfer for a set standby time every time one byte is transferred. Hereinafter, the operation of the system of the specific example 1 will be sequentially described with reference to a flowchart.

The application 4 of the host computer 1 shown in FIG. 1 generates predetermined print data. The operating system 5 receives the print data from the application 4 and passes it to the printer driver 6.
The printer driver 6 converts the print data into a command that can be recognized by the printer 3 and passes the command to the port driver 7. The port driver 7 converts the data received from the printer driver 6 according to the specifications of the interface according to the IEEE standard.
E1284 Transfers to the output unit 8. In this process, the port driver 7 adjusts the transfer speed.

FIG. 5 shows a system operation flowchart of the first embodiment. This flowchart shows the operation of the port driver 7. First, in step S1 of the figure, the transfer speed adjustment unit 13 of the port driver 7
The setting value of the transfer speed received from the printer driver 6 via the processing unit 11 is set in SetSpeed. This Se
tSpeed indicates the optimum data transfer speed required by the printer. Note that SetSpeed, DummySize, Count1,
TransSpeed, Count2, and TransSpeed2 are names indicating variables in which data is set when executing the arithmetic processing. In step S2, the dummy data 16 is read, and its size is set to DummySize. In the next step S3, the wait counter is set to Count
The transfer speed TransSpeed1 at 1 is obtained. This wait counter is used when actually measuring the transfer speed, and holds a waiting time for waiting for transfer every time one byte is transferred.

TransSpeed1 obtained in step S3 is an apparent transfer speed when the waiting time is Count1.
In step S4, an apparent transfer speed TransSpeed2 when the waiting time is Count2 is obtained. The counts Count1 and Count2 of the weight counter are held in advance by the counter generator 15 of the port driver 7 shown in FIG. This is read and used by the transfer rate adjusting unit 13.

FIG. 6 shows the above steps S3 and S3.
4 shows a flowchart for obtaining an apparent transfer speed in FIG. (A) is a flowchart for calculating the transfer speed TransSpeed1. (B) Transfer rate TransS
It is a calculation operation flowchart of peed2. First, (a)
In step S1, the value Count1 received from the counter generator 15 is set in the weight counter. Next, in step S2, the timer 14 is started. The timer 14 includes a digital counter and the like. For the data transfer unit 12, the dummy data 16 and the dummy data size DummySize, the value of the wait counter Count1
To issue a data transfer instruction.

The data transfer unit 12 includes a transfer speed adjustment unit 13
Each time 1 byte dummy data is transferred using these values received from
The transfer waits for Count1 and transfers all the dummy data. When the transfer of the dummy data 16 for the dummy data size "DummySize" is completed, in step S5, the timer 1
4 is stopped, and the timer value at that time is set to Time1. In step S6, the dummy data size DummySiz
The transfer rate at that time is calculated from e and the timer value Time1. (B) is the same processing as (a) except that the value of the wait counter is changed to Count2 and the apparent transfer speed TransSp
Calculate eed2. The arithmetic expression is as follows. TransSpeed1 (when the value of the weight counter is Count1) = Time1 / DummySize (1) TransSpeed2 (when the value of the weight counter is Count2) = Time2 / DummySize (2)

Next, the process proceeds to step S5 in FIG. 5, in which the obtained two apparent transfer speeds TransSpeed1 and TransS1 are determined.
peed2 and the counter value Co at the time of each transfer rate measurement
The transfer rate reduction rate Dec when the counter is increased by "1" is calculated from unt1 and Count2.

FIG. 7 is a diagram for explaining the calculation of the transfer rate reduction rate. The horizontal axis shown in this figure represents the value of the weight counter, and the vertical axis represents the actually measured apparent transfer rate. As shown in the figure, a point P when the apparent transfer rate is measured by setting the value Count1 of the weight counter, and a point Q when the apparent transfer rate is measured by setting the value Count2 of the weight counter. Is connected by a straight line, the reduction rate of the transfer rate is calculated. That is, the slope of this straight line is
This corresponds to the rate of change of the transfer speed when the value of the wait counter is decreased by “1”. This calculation formula is shown in (1) below.
It is as shown in the equation. Dec = | TransSpeed1-TransSpeed2 | / | Count1-Count2 | = | Transfer speed 1-Transfer speed 2 | / | Weight counter 1-Wait counter 2 | (3)

With this, it is possible to calculate the value of the weight counter to determine what value the apparent transfer speed changes. Thus, the value of the wait counter for obtaining the optimum transfer speed is determined. This is set in the loop counter 17 shown in FIG. The loop counter 17 is a register that stores a standby time when data is actually transferred. For example, if the performance of the printer is 600 dpi (dot / dot)
Inches), the printing speed is 4 ppm (pages / minute), and the receiving buffer size is 128 kilobytes. When printing on letter size paper with such a printer,
The transfer speed of the print data is as follows.

First, letter size paper is 11 inches long and 8.5 inches wide. The maximum value of the data size for printing on this paper is 11 × 600 × 8.5 × 6.
00 = 33660000 (bits). That is, the data size is about 4 megabytes. When this data is printed at the speed described above, the amount of data that must be transferred per second is as follows. 4 megabytes x 4 ppm / 60 seconds = 280 kilobytes /
Second

The transfer speed is a speed at which the printer continuously receives data at a constant speed. However, in a host-based printer that does not have a reception buffer having a sufficient capacity to store one page of data, the data transfer speed is set higher than this value, and data is intermittently received. The set value of the data transfer speed of the host computer is set in SetSpeed as described above. At this time, the weight counter Count1
Using the apparent transfer speed TransSpeed1 and the decrease rate Dec, the formula for obtaining the optimum waiting time, that is, the value of the loop counter, is expressed as follows. Loop counter = (TransSpeed1-SetSpeed) / Dec + Count1 (4)

For example, from a host computer incorporating a 386SX / 25 MHz processor whose operation clock is slower than that shown in FIG.
If you want to transfer data with tSpeed of 400 kilobytes,
The value of the loop counter is obtained as follows.
The size of the dummy data is 64 kilobytes. Transfer time Time when wait counter Count1 is set to "1"
1 is 130 ms, and the transfer speed at this time TransSpeed
1 was 480 kilobytes / sec according to the above equation (1).

The wait counter Count2 is set to "1".
The transfer time Time2 when it is set to 0 "is 320 ms,
The transfer speed TransSpeed2 is 200 kilobytes / second according to the above equation (2). When this is applied to the above equation (3), the reduction rate Dec is calculated by the following equation. (480-200) / (10-1) @ 27 kilobytes /
From the above results, the value of the loop counter is calculated from the above equation (4) as follows. (480−400) /27+1=3.96≒4 Therefore, in this example, it can be seen that if the value of the loop counter is set to “4”, data can be transferred at SetSpeed, that is, the optimum transfer speed required by the printer. Next, an example of a data transfer operation using this loop counter will be described.

FIG. 8 is a flowchart showing the data transfer operation of the port driver 7 shown in FIG. This data transfer operation is the same whether the dummy data is transferred to measure the apparent transfer speed or the data to be actually printed by the printer. First, in step S1, the data transfer unit 12 sets the data size to be transferred to the printer 3 received from the I / F processing unit 11 to SubSize. When transferring dummy data,
Dummy data is received from the transfer speed adjusting unit 13. Therefore, this is shown in the figure.

Next, in step S2, the weight processing unit 18 shown in FIG. 1 sets the value of the weight counter received from the loop counter 17 to SubCount. next,
In step S3, the data transfer unit 12 reads and outputs one byte of data to be transferred. In step S4, the weight processing unit 18 decrements the SubCount, and determines in step S5 whether or not this value has become "0". That is, here, the transfer is waited for the wait counter. When the transfer wait is completed for the wait counter, that is, the wait time, the process proceeds to step S6,
The data transfer unit 12 decrements the size of the transfer data. Then, in step S7, it is determined whether or not all the transfer data has been transferred. Steps S2 to S2 are performed until all the data has been transferred.
Step 7 is repeated.

In the above example, the transfer rate reduction rate is calculated based on the difference between the apparent transfer speeds when the transfer is performed at different standby times. No problem.

<Effects of Specific Example 1> As described above, before the data transfer, the apparent transfer speed when a predetermined amount of dummy data is transferred for an arbitrary standby time is measured, and the apparent transfer speed is measured. If the standby time is selected from the relationship between the speed and the standby time, data transfer from the host computer 1 to the printer 3 can be performed at an optimal transfer speed according to the combination of the host computer 1 and the printer 3.

The data transfer process can be applied not only to data transfer to a printer but also to data transfer to various external devices. In addition, since the data transfer rate is actually measured by actually transferring dummy data, the apparent data transfer rate based on various factors such as the operating clock of the host computer processor, the configuration of the interface, and the buffer size of the printer can be accurately determined. And the transfer speed can be optimized.

<Specific Example 2> This specific example is applied to a case where the processor of the host computer has an operation clock faster than that of the above example. As above,
Even if the optimum standby time is calculated by actually measuring the apparent transfer speed, an error may occur from the actual one. In this example, the apparent transfer time is actually measured using the selected standby time from the result of the arithmetic processing, an error from the target data transfer rate is detected, and the standby time is further corrected. Since the configuration of the system is the same as that shown in FIG. 1, illustration of the block diagram is omitted.

FIG. 9 shows a system operation flowchart of the second embodiment. This is an improvement from step S5 of the system operation of the specific example 1 shown in FIG. Therefore, the processes from step S1 to step S4 shown in FIG. 5 are the same as those in the specific example 1, and are not shown. In step S1 in FIG. 9, the transfer rate reduction rate Dec when the counter is incremented by "1" is calculated in the same manner as in the first embodiment.

In step S2, the value of a loop counter for approaching the transfer speed setting value SetSpeed requested by the printer is calculated. Here, when the host processor operates on the system clock of the high-speed processor of 486DX or more shown in FIG. 2, the relationship between the transfer speed and the wait counter cannot be represented by a straight line.

FIG. 10 is a diagram for explaining an error of the weight counter. As in FIG. 7, the vertical axis of the graph indicates the transfer speed, and the horizontal axis indicates the value of the weight counter. In the specific example 1, the relationship between the transfer speed and the weight counter was approximated by a straight line as indicated by a broken line in the figure. However, when dummy data is actually transferred using the loop counter obtained by calculation as a weight counter and the result is plotted, the relationship between the transfer speed and the weight counter slightly curves as shown by the solid line in the figure.

Therefore, when data transfer is performed using the value C1 of the wait counter when the transfer speed is SetSpeed using the straight line shown by the broken line as in the first embodiment, the actual transfer speed becomes SS1. Therefore, step S4 in FIG.
As shown in (1), the value of the loop counter is corrected in consideration of the difference between the actually measured transfer speed SS1 and the target transfer speed SetSpeed. The data transfer described above is performed using the corrected loop counter value (step S in FIG. 9).
5).

FIG. 11 shows a flowchart of the error correction operation. First, in step S1, the dummy data 16 shown in FIG.
Set to ize. Next, in step S2, the value of the loop counter is set in the weight counter Count3. This is a value corresponding to C1 in FIG. Then, in step S3, the timer is started. In the next step S4, data such as dummy data, dummy data size, and a weight counter are passed to the data transfer unit 12 to issue a data transfer instruction. Data transfer unit 12
Uses the received value to set the waiting time C1
The dummy data is transferred while only waiting for transfer.

When the transfer of the dummy data is completed, the timer 14 is stopped in step S6, and the timer value at that time is set in Time3. In step S7, the transfer rate is calculated from the dummy data size and the timer value. In step S8, it is determined whether or not the transfer speed thus obtained is equal to or less than the optimum transfer speed SetSpeed of the target printer. If the actually measured transfer speed is lower than the target, the process proceeds to step S9, and the counter is incremented and corrected. If it is larger than the target, the process proceeds to step S10, in which the counter is decreased to perform correction.

FIG. 12 is a flowchart showing the operation in the case where the correction is performed by decreasing the counter. First, step S
1, the value of the loop counter in which the error occurs is CtrCount.
Set to 1. Next, in step S2, the dummy data is read out and its size is set to DummySize. Then, in step S3, the value of the loop counter is decreased by one and set in the weight counter (step S4). In step S5, a timer is started.

Thereafter, in step S6, the data transfer speed is actually measured by the value of the wait counter in the same manner as described above. Obtained timer value Time4
Is used in step S7 to calculate the actual data transfer rate. In step S8, it is determined whether the data transfer rate has exceeded a target value. If not, the process returns to step S3, and the value of the wait counter is further reduced. Thus, the processing of steps S3 to S8 is repeated while the value of the weight counter is reduced until the value exceeds the target value.

If the value exceeds the target value, the flow advances to step S9 to return the value of the weight counter by one. Then, in step S10, this value is determined as the final value and saved in the loop counter 17. This completes the correction of the waiting time.

FIG. 13 is a flow chart of the operation when the counter is incremented for correction. The only difference from the processing shown in FIG. 12 is that the value of the weight counter is incremented by "1" at step S3. When the value of the weight counter reaches the target value, the value is set in the loop counter 17 as in the case of FIG. Thus, in any case, the actual measurement is repeated until the value of the loop counter approaches the target value to optimize the transfer speed.

The processing described in the first and second embodiments may be automatically performed before the start of printing. For example, it is preferable that the control program be started automatically when the host computer is connected to the printer and the printer is turned on. Further, the processing may be started at an arbitrary timing according to an instruction from the operator.

<Effect of Specific Example 2> With the above processing, when a host computer with a high-speed operation clock is connected to a printer, the transfer speed is corrected by actual measurement in addition to the optimization of the transfer speed by arithmetic processing. Therefore, it is possible to make the transfer speed closer to the optimum value.

<Third Embodiment> In the third embodiment, an example will be described in which the speed is adjusted so that the required accuracy of the data transfer rate falls within an error of several tens of kilobytes per second or less. In the above example, the apparent transfer rate was measured using the timer 14 provided in the port driver 7 of the host computer 1. However, a timer with higher accuracy than the host computer may be provided on the printer 3 side. In such a case, the transfer rate can be optimized with high accuracy by measuring the apparent transfer rate on the printer side, not on the host computer side.

FIG. 14 is a block diagram showing the system configuration of the third embodiment. The illustrated host computer 1 has the same configuration as that of the specific example 1. The same reference numerals are given to the same parts of both. Note that the port driver 7
The timer 14 used in the specific example 1 is unnecessary. This is to measure the apparent data transfer rate using the timer on the printer side. The printer 3 shown includes a data receiving unit 20,
A data analysis unit 23 and a printing unit 24 are provided. The data receiving section 20 is provided with a receiving section 21 for receiving data transferred from the host computer, and a timer 22 having the same role as that for measuring the data transfer rate in the first embodiment.

FIG. 15 is an explanatory diagram of the system operation of the third embodiment. Also in the case of the specific example 3, an apparent data transfer rate measurement process similar to that of FIG. 5 is performed. That is, in steps S3 and S5 in FIG. 5, an operation of obtaining the apparent transfer speed while changing the weight counter is performed. Steps S1 to S7 in FIG. 15 correspond to the processing in FIG. 6A or 6B.

First, in step S1 of FIG. 15, the value received from the counter
Set to Count6. Next, in step S2,
The transfer time measurement start command is transferred to the printer 3. Thus, the timer 22 of the printer 3 (FIG. 14)
Is activated (step S8 in FIG. 15).

Next, in step S3 of FIG. 15, a dummy data, a dummy data size, a weight counter, and the like are passed to the data transfer unit 12 to issue a data transfer instruction. In step S4, using the value received by the data transfer unit 12, the dummy data is transferred while using the waiting time set in the wait counter. This dummy data is received by the printer as shown in step S9 in FIG.

Next, when the transfer of the dummy data is completed, a data transfer end command is transferred from the host computer 1 to the printer 3 in step S5. On the printer side, in step S10, upon receiving the data transfer command, the timer 22 is stopped, and the timer value is returned to the host computer 1. In step S6, the host computer 1 receives the timer value from the printer 3 and sets the timer value to Time6. After that, the apparent transfer rate is calculated from the dummy data size and the timer value (step S6, step S6).
7).

In the first embodiment, two types of weight counters are set, and the rate of decrease in transfer speed when the weight counter increases by "1" is calculated. In the specific example 3, FIG.
The processing shown in FIG. 5 is executed by setting different values of the weight counters. Thus, in the same manner as in Example 1,
Optimize the transfer speed.

Usually, many timers of the host computer 1 have an accuracy of about several tens of milliseconds.
The standby time set in includes an error of about several tens of millimeters. Therefore, if the required accuracy of the transfer rate is high, it is difficult to satisfy the accuracy. On the other hand, if the accuracy of the timer 22 (FIG. 14) of the printer 3 is on the order of a few microseconds, the apparent transfer time can be measured sufficiently accurately.

<Effect of Specific Example 3> When a high accuracy is required for the data transfer speed, the use of the timer on the printer side enables more precise optimization of the transfer speed. Other effects are the same as those of the first embodiment.

<Example 4> As described above, even if the transfer speed is optimized, normal data transfer may not be performed due to the influence of the interface. For example, there is a case where the waveform of a pulse flowing through the signal line is broken due to the impedance of the interface cable, so that synchronization cannot be achieved. Such a phenomenon is herein referred to as data loss due to rounding. If data loss occurs due to dullness, the data transfer speed may be further reduced. Therefore, a method of detecting occurrence of data loss due to rounding and determining how much the data transfer speed is reduced will be described in this specific example.

FIG. 16 is a block diagram showing a system configuration of the fourth embodiment. The illustrated host computer 1 has the same configuration as that of the specific example 1. The same reference numerals are given to the same parts of both. The port driver 7 includes
A high counter 26 and a low counter 27 are provided. This is for setting two types of standby times and measuring the apparent data transfer speed in each case. The printer 3 is newly provided with a sum check unit 28 for counting and counting the number of bytes of the received data.

The interface cable connecting the host computer 1 and the printer 3 uses eight signal lines. In order to change all the contents of the data transmitted to these signal lines, 0-6
Use 64 kilobytes of data between 5535. 1
This is because the content of data flowing through the signal line is changed every time byte transfer is performed, and data loss due to rounding is monitored.

FIG. 17 is a diagram for explaining data loss due to rounding of signal lines and a preventive measure. FIG. 7A shows a state in which 8-bit data is sequentially transferred in serial. It is assumed that the signal level of any one of the signal lines changes at the timing shown in FIG. (B) is a strobe for notifying the timing for receiving data on the printer side. This strobe is also transferred to the printer together with the data through the interface cable.

In the printer, each data is fetched into the reception buffer at the timing when the level of the strobe rises from the low level to the high level and at the timing when the level of the strobe falls from the high level to the low level. In the example of FIG.
, The first data is fetched, the next data is fetched at time t2, and the last data is fetched at time t3. When the strobe signal becomes dull, the following state occurs.

(C) is the same data as (a).
(D) is a strobe. This strobe is rounded at the timing from time t1 to t2 shown in the figure. Time t when this n strobe goes low
In step 1, the first data is fetched, and when the n strobe goes high, the next data is fetched. However, since the signal is rounded, if data is to be taken in at time t2 when the signal has reached the high level, the next data has already been input, and one data drop will occur.

In the present invention, in order to prevent such a problem, the data transfer speed is partially adjusted in a portion where data rounding is likely to occur. (E) shows the data content when the data transfer is delayed by the time T at the time t2 in the figure. The strobe shown in (f) rises to a predetermined level during this time, and enables the capture of the second data. That is, at the timing when the strobe rises from the low level to the high level, a waiting time by the wait counter is inserted for the time T to prevent data loss. Hereinafter, the specific operation will be described using a flowchart.

FIGS. 18, 19 and 20 are flowcharts for explaining the operation of the fourth embodiment. First, FIG.
In step S1 of FIG. 8, the transfer rate reduction rate Dec is calculated as described in the above specific examples. Then, in step S2, the transfer speed is set to the transfer speed set value SetSpe.
The loop counter required to approach ed is calculated, and the calculation result is stored in the high counter 26 and the low counter 27. The high counter 26 is a counter for setting a standby time when the strobe shown in FIG. 17 is at a high level. The low counter 27 is a counter for setting a standby time when the strobe shown in FIG. 17 is at a low level. Therefore, two types of standby time are used depending on the state of the strobe. Step S
At 3, the dummy data 16 is read out and its size is set to DummySize.

Next, a rounding confirmation command is transferred to the printer 3. That is, while the dummy data is being transferred, the printer is notified that the occurrence of rounding is to be confirmed.
In step S6, the transfer speed adjustment unit 13 issues a data transfer instruction by passing the size of the dummy data 16 and the dummy data to the data transfer unit 12. In step S7, the data transfer unit 12 uses the received value to transfer the dummy data while waiting for transfer with the value set in the row counter 27. When the transfer is completed, a data transfer end command is transferred to the printer 3 in step S8.

At step S 9, the number of received data and the sum check data are received from the printer 3. The number of received data is displayed in, for example, a unit byte. The sum check data indicates the number of received data. It should be noted that if the number of data is counted and displayed as it is, the numerical value increases. For example, only the lower bits thereof are used as the sum check data. The sum check processing unit 20 of the printer 3 has a function of performing this sum check and notifying the result to the port driver 7. In step S10, the number of received data received from the printer 3 is compared with the dummy data size. Further, the sum check data received from the printer 3 is compared with the sum check result of the dummy data calculated by the host computer. If any of them is different, the rounding of the signal line is adjusted. The rounding adjustment is performed by extending the standby time and decreasing the data transfer speed. This rounding adjustment process will be described with reference to FIG.

FIGS. 19 and 20 are flowcharts showing the rounding adjustment processing of the signal lines. At the time of adjusting the transfer speed, a data transfer end command was transferred to the printer at the end of the dummy data transfer. The transfer speed adjustment unit 13
The byte count DataCount of the received data and the sum check data A are received from the printer 3. Transfer speed adjustment unit 13
Is the dummy data size DummySize and the number of received data Dat
aCount is compared with the sum check data A and the sum check data B of the dummy data 16 calculated by the transfer speed adjusting unit 13 itself. When these data are the same, it is determined that the signal line is not rounded. If any one of the data is different, it is determined that the signal line is dull.

Here, in step S1 in FIG. 19, the value of the row counter is set in the adjustment counter CtrCount1. Also, adjust the value of the high counter CtrCount
Set to 2. Next, in step S3, a rounding confirmation command is transferred to the printer 3. Further, in step S4, the dummy data 16 is read, and its size is set to DummySize. Next, in step S5, the dummy data is output to the one-byte printer.
Then, in step S6, nStrobe is set to a high level (valid). Thus, the printer 3 is notified that the data has been transferred by one byte.

Next, in step S7, the value CtrCount1 of the adjustment counter is set in the weight counter Count8. Then, in step S8, Count8 is decremented. Step S9 is a process for determining whether or not the time corresponding to the wait counter has elapsed when the strobe is at the high level. In this way, when the standby time corresponding to Count8 has elapsed, the process proceeds to step S10,
Decrement the size of dummy data. This is for counting the data to be transferred one byte at a time and checking whether all data has been transferred. And step S
At 11, it is determined whether the size of the dummy data has become "0". That is, it is determined whether the transfer of all the dummy data has been completed.

If all the dummy data has not been transferred, the process proceeds to step S12 in FIG. Then, one byte of dummy data is read out again and output. Furthermore,
In step S13, nStrobe is set to a low level. This is the process in the state where the strobe is at the low level. In step S14, the value of the adjustment counter CtrCount2 is set in the weight counter Count9. Then, in step S15, Count9 is decremented. Step S16 is a process for determining that the time set in Count9 has elapsed.

After the elapse of the standby time, step S1
Proceeding to 7, the size of the dummy data is decremented.
Then, it is determined again whether the dummy data size has become “0”. If the dummy data size is not "0", the process returns to step S4. That is, the processes of steps S4 to S11 shown in FIG. 19 and the processes of steps S12 to S18 shown in FIG. 20 are alternately repeated, and these processes are executed until the dummy data size becomes “0”.

Thereafter, the flow advances to step S19 to notify the printer 3 of the end of the dummy data transfer. Step S20
Then, the number of data received by the printer 3 is counted, and this is notified to the transfer speed adjusting unit 13. Furthermore, the transfer rate adjusting unit 13 is notified of the sum check data Check2. In the next steps S21 and S22, the size of the dummy data is compared with the number of data actually transmitted and the number of data received by the printer, and it is determined whether or not they match.

If they do not match, the process proceeds to step S25, where the value of the weight counter is changed. In this example, the standby time when the strobe is at a low level is reduced, and the standby time when the strobe is at a high level is sequentially extended. Therefore, the pulse waveform is deformed as shown in FIG. And
Again, the apparent data transfer rate is actually measured by the waiting time. In this way, a waiting time during which no data loss occurs is selected, and these values are stored in the low counter and the high counter in steps S23 and S24. In this example, the standby time when the strobe is at the low level is used, and the sum of the standby times when the strobe is at the high level is not changed. Therefore, even if this adjustment is made, the apparent data transfer time does not change. is there.

FIG. 21 is a flowchart showing the outline of the processing of the data receiving section on the printer side in the above-described processing. In step S1, the sum check data is reset when the rounding confirmation measurement command is received. In step S2, a sum check process is performed each time 1-byte data is received. Then, in step S3, when the data transfer end command is received, the number of received data and the sum check data are returned to the host computer 1.

With the above processing, the presence or absence of data loss due to dummy data transmission / reception is checked. If data loss occurs, the standby time is partially adjusted at a predetermined timing to optimize the data transfer speed. Plan.

<Effect of Specific Example 4> As described above, the apparent data transfer speed is adjusted to the optimum value, and when data loss occurs due to signal lines and other environmental conditions, the predetermined timing is set. , The standby time is partially corrected, so that the data transfer speed can be optimized and the reliability can be improved.

<Embodiment 5> In the above embodiments, the host computer has the function of adjusting the data transfer rate. In this specific example, the data receiving printer is provided with a data transfer speed adjusting function. In particular,
When the printer receives data, it outputs a busy signal to the host computer at a predetermined timing, and suppresses data transmission each time. This optimizes the apparent data transfer rate.

FIG. 22 is a system block diagram for realizing this. As shown in the figure, a host computer 1 includes an application 4, an operating system 5, a printer driver 6, a port driver 7, an IEEE
An E1284 output unit 8 and the like are provided. These configurations are:
This is the same as the above specific example. The data receiving unit 30 of the printer 3 is provided with a weight processing unit 32, a receiving speed measuring unit 33, a receiving speed adjusting unit 34, a weight counter 35, and a timer 36 in addition to the receiving unit 31. The data receiving unit 30 stores a maximum receiving speed value 37, and this value is set as the optimum receiving speed of the printer.

The receiving speed measuring unit 33 is a unit that measures the receiving speed of the data received by the receiving unit 31 from the host computer 1 in a manner such as a number of bytes per unit time. The reception speed adjustment unit 34 calculates the maximum reception speed value 3
7 is a section for setting an optimum receiving speed and controlling the actual receiving speed to approach the optimum receiving speed. Timer 3
Reference numeral 6 is used to measure an actual data reception speed and the like. The wait counter 35 is a counter for setting a waiting time for waiting for data transfer every time 1-byte data is transferred, as described in the specific examples so far. In the case of this example, it means the time for suppressing data transfer rather than waiting for data transfer.

In this example, the weight processing section 32 outputs a busy signal to the host computer 1 through the receiving section 31. The output time of this busy signal is a waiting time.
While the busy signal is being output, the data transfer from the host computer 1 is temporarily stopped. This has exactly the same function as the transfer standby time on the host computer side.

FIG. 23 is a diagram for explaining a method of the transfer speed optimizing operation in the specific example 5. FIG. 3A shows the timing at which data is transferred at the transfer speed of the host computer. (B) is an nStrobe signal (simply called a strobe as in the description so far) that controls the timing at which the data is taken in by the printer. In this case, data is fetched at the rising edge of the strobe. (C) is a busy state for suppressing data transmission periodically when the printer takes in data (Busy).
Signal. Normally, the busy signal becomes valid at the timing of the rising edge of the strobe,
Data transfer between the host computer and the printer is performed. However, if the transfer rate is too fast for the printer, this embodiment extends the time during which the busy signal is made valid (the time when it goes high). The time during which this busy signal becomes valid determines the waiting time described above.

(D) shows the data transfer timing when the time during which the busy signal becomes valid is extended. (E) is an nStrobe signal transferred from the host computer to the printer. (F) shows a busy signal for controlling an apparent data transfer rate after data is taken. As described above, by extending the time during which the busy signal becomes valid from the time (t1) to the time (t2) in the drawing, the apparent data transfer speed can be controlled to be reduced.

FIG. 24 is a flowchart showing the outline of the receiving speed adjusting process according to the fifth embodiment. First, in step S1, the receiving unit 31 shown in FIG. 22 starts the timer 36 when data is transferred from the host computer 1. Next, in step S2, DataSize
At the point when the number of data set in
6 is stopped, and the value at that time is set to Time. The receiving unit 31 passes the received data number DataSize and the timer value Time to the receiving speed measuring unit 33. DataSize of this received data
Is predetermined for calculating the data reception speed, and may be an arbitrary number.

In step S4, the reception speed measurement unit 33 calculates the reception speed from the received value, and
Set to eed. The reception speed can be obtained by dividing the received data by the time measured by the timer 36. In the next step S5, an optimum receiving speed is obtained based on the maximum receiving speed value 37, and is set in a register OptimumSpeed provided inside the receiving speed measuring unit 33.

Then, in step S6, it is determined whether the reception speed obtained by the calculation is higher than the optimum reception speed. If it is not larger, the adjustment is not necessary and the process is terminated. If it is larger, the process proceeds to the next step S7, where the receiving unit 3
1 and the reception speed adjustment unit 34 are called. Then, proceeding to step S8, the reception speed adjustment unit 34 adjusts the time during which the busy signal is valid so that the reception speed becomes equal to or less than the optimum value.

As described with reference to FIG. 23 (f), the time for making the busy signal valid (high level) is calculated and stored in the wait counter 35. This calculation is
It is obtained by subtracting the optimal receiving speed OptimumSpeed from the actual data receiving speed Speed obtained as described above, and dividing the difference by the above-mentioned received data number DataSize. The result of this division is the waiting time. The time for setting the busy signal to low level is delayed by this time, and the time for making the busy signal valid (high level) is extended. This result is set in the wait counter.

In step S9, the receiving unit 31 calls the weight processing unit 32 every time one byte of data is received.
In step S10, the weight processing unit 32 delays the timing of setting the busy signal to low based on the value of the weight counter 35. Thus, step S11
The receiving unit 31 operates to set the busy signal to low when the processing returns from the weight processing unit 32.

<Effect of Specific Example 5> As described above, FIG.
The reception speed can be optimized by adjusting the time during which the busy signal is made effective as shown in FIG. Also, this control can be performed by the data receiving unit on the printer side, unlike the above specific examples. Further, since the receiving speed of the data transferred from the host computer can be optimized on the printer side, even if the transfer speed optimizing function is not provided in the printer driver or the like of the host computer, the effect as in the specific examples described above can be obtained. Obtainable.

<Embodiment 6> In this embodiment, a direct memory access controller that automatically receives data from a host device is used on the external device side. It is assumed that the direct memory access controller has the ability to withstand high-speed data transfer by the host device. However, the direct memory access controller stops operating once it has received the amount of data that can be received in the reception buffer. After the data in the reception buffer is taken into the external device, the direct memory access controller restarts the reception operation again. Therefore, if the next data is transferred from the host device before that, the data cannot be received. For example, when the processing speed of the data received from the host computer by the printer is slow, the same trouble as underrun described above occurs.

Therefore, in this specific example, the control for outputting the busy signal as described in the specific example 5 is performed every time data can be received collectively by the direct memory access controller. The configuration of the system itself may be the same as that described with reference to FIG.

FIG. 25 is a timing chart of the optimization method in the specific example 6. (A), (b),
The timing shown in (c) indicates a state in which data is transferred from the host computer to the printer without performing any optimization processing. (A) is a data transfer timing, (b) is an nStrobe signal for taking in the data,
(C) is a busy signal transmitted from the printer side to the host computer. The content of each signal is described in Example 5.
Is the same as

The following (d), (e), and (f) show the control of the specific example 6 for comparison with the specific example 5.
This is similar to (d), (e), and (f) of FIG.
That is, every time one byte of data is received, the busy signal to be turned to low level at time t1 and time t4 is extended by T time,
The reception timing of the data to be received at the timings of time t2 and time t5 is shifted to 3 and time t7. However, when the direct memory access controller is used, high-speed reception according to the transfer speed of the host computer is possible. The data thus received is stored in a buffer memory of a printer (not shown).

When the buffer memory becomes full, the printer reads out the data at the optimum speed and executes printing. Therefore, if the transfer timing of data to the buffer memory is adjusted, the data transfer speed of the direct memory access controller can be made closer to the optimum transfer speed for printing by the printer.

(G), (h), and (i) show the control of the specific example 6. That is, the data is received at the transfer speed of the host computer side for data transfer by the direct memory access controller until time t8 in the figure. Then, at this timing, the busy signal is extended by 3T from time t8 to time t11 and output as shown in the figure.
Therefore, data transfer by the host computer is suppressed from time t8 to t11. By doing so, as shown in (f) of the figure, the T time from time t2 to t3, the T time from time t6 to t7, and the extension time T time from time t9 to time t10 are combined, and This means that the time has moved from t8 to time t11. This allows
In the case shown in (f) and the case shown in (i), the average data transfer rate over a sufficiently long period is equal.

FIG. 26 is a flowchart showing the operation of the sixth embodiment. First, in step S1, the size of data to be transferred is set to TotalSize. Next, in step S2, the DMAStatusFlag is turned on. this is,
This is a step for determining whether or not preparation for DMA (Direct Memory Access Controller) processing has been completed. In the default state, since this flag is off, the process proceeds to step S3 to inquire the DMA specification, and set the number of data that can be received at one time by the direct memory access controller to DMASize. In step S4,
Turn on the status flag of the direct memory access controller.

Next, the value of DMASize is set in TransferSize as the data size to be transferred. Next, step S6
, One-byte data is read from the memory and output. As for the DMA specifications, the host computer inquires the printer and the DMA specifications are stored in a buffer on the host computer side. DMAStatusFla
g is set one for each device, that is, one external device connected to the host computer. This is to prevent the same external device from inquiring about the DMA information repeatedly. This flag is set in response to an inquiry when the external device is powered on, and is reset to off when the external device is powered off.

In the next step S7, the size TotalSize of the data to be transferred is decremented. This is for displaying the remaining data when transferring 1-byte data. In step S8, it is determined whether this TotalSize is "0". If it is "0", the process ends because all data transfer has ended. If it is not "0", the process proceeds to step S9, and the number of receptions that the DMA can receive at one time is decremented.

In the step S10, it is determined whether or not this becomes "0". If not "0", step S
Returning to No. 6, data transfer is repeated one byte at a time. When the DMA transfers the data for the number of data that can be received at one time, the process proceeds from step S10 to step S11. The value of the weight counter obtained in the specific example 6 is multiplied by DMASize, and this is set as a new value of the weight counter. That is,
If the transfer is performed byte by byte and the wait time for the wait counter is set by a busy signal, the DMASize bytes that can be transferred at a time by the direct memory access controller are collectively set as a new time. Using this, the control shown in FIG. 25 (i) may be performed.

In the next step S12, the wait counter thus set is decremented, and the standby time is measured. That is, in step S13, it is determined whether or not this wait counter has become "0", and a wait is performed for the standby time. When the time corresponding to the wait counter has elapsed, the process returns to step S5, and the processes of steps S5 to S13 are repeated again. When all data transfer ends in this way, the operation ends.

In the flowchart of FIG. 26, an example in which the data transfer speed is adjusted by the busy signal on the printer side described in the specific example 5 has been described. However, the method of the specific example 6 is similarly applied to the case where the standby time is controlled using the loop counter on the host computer side as described in the specific example 1 and the like. In this case, FIG.
Is replaced by the value of the loop counter. The control itself for obtaining the value of the loop counter may be as described in the first embodiment.

<Effect of Specific Example 6> Data can be transferred at high speed according to the performance of the direct memory access controller provided in the printer, while the number of data that can be received by the direct memory access controller at one time is taken into consideration. Since a fixed waiting time is inserted every time this data amount is received, the transfer speed can be optimized as in the above-described specific examples. Also, unlike the specific examples 1 and 5 in which the transfer speed is adjusted every time one byte is transferred, the control for waiting for time is simplified, so that the load on the host device and the printer device can be reduced.

<Embodiment 7> FIG. 27 is a block diagram showing a system of Embodiment 7. In this specific example, an example in which a plurality of external devices are connected to the host computer 1 will be described. FIG. 28 shows an explanatory diagram of the state of the specific device. As shown in the figure, for example, a modem 41, a hub 42, a printer 3, and the like are connected to the host computer 40. The host computer 40 simultaneously controls communication with these devices. Therefore, printer 3
The control of the data transfer speed is different from that in the case where only one is connected to the host computer 40.

The host computer 40 shown in FIG. 27 is provided with applications 4A, 4B, 4C, an operating system 5, a printer driver 6, a port driver 7, an IEEE1284 output unit 8, a network driver 43, a serial driver 44, and the like. I have. The network driver 43 is a driver that controls the hub 42 and the like. In addition, the serial driver 44
This is a driver for controlling 1 and the like.

The external configuration of this system is shown in the following figure.
FIG. 28 is an explanatory diagram of the state of the connected device in the specific example 7. The host computer 40 shown in FIG.
The modem 41, the hub 42, and the laser printer 3 are connected.

The printer 3 connected to the IEEE1284 output unit 8 includes a data receiving unit 45, a data analyzing unit 23, a printing unit 24, and the like. The overall configuration of these is almost the same as the above specific examples. The port driver 7 of the host computer 40 includes an I / F processing unit 11, a data transfer unit 12, a transfer speed adjustment unit 13, a counter generation unit 15, dummy data 16, a loop counter 17, a wait processing unit 18, and a timer 46. Have. The basic functions of each part of the port driver are almost the same as those described in the specific example 1 and the like. The operation unique to the specific example 7 will be described with reference to the following drawings.

FIG. 29 is an explanatory diagram of the amount of data transferred to the printer in one second. FIG. 7A shows an example in which only the printer is connected to the host computer 40 and operates. The horizontal axis of this graph is time. The vertical axis indicates the amount of data transferred per unit time. From time t1 to time t
Up to 2, data is transferred at a predetermined constant data transfer speed and printing is performed. (B) shows control when there is a device that performs transmission and reception other than the printer.

The amount of data transferred during the period from time t1 to time t2 in (a) is equal to the time t1 to time t2 in (b).
It matches the amount of data transferred in the time up to 2. (B)
In the case of, the control of the printer is changed from time t1 to time t2.
Perform only between From time t2 to t3, facsimile control is performed, and from time t3 to time t4,
Network control is performed. Facsimile control is performed through a modem 41, and network control is performed through a hub 42.

In such a case, when transferring the same amount of data to the printer as shown in (a), more data must be transferred to the printer per unit time from time t1 to time t2. . Therefore, in order to equalize the data amounts D1 and D2 in the figure, the transfer speed is increased in the case of (b). In the specific examples so far, since the transfer rate is set without considering the connection of other external devices, if a plurality of external devices are controlled simultaneously, the data transfer speed will be lower than expected. In this specific example, the transfer speed is optimized.

FIG. 30 is a flowchart of the process when power is turned on in the seventh embodiment. This processing is started when the power of the host computer 40 shown in FIG. 27 is turned on. First, in step S1, the transfer speed of the host computer is checked and set to MaxSpeed. Next, in step S2, after checking the transfer speed, the transfer speed adjusting unit 13 checks the optimum receiving speed of the printer, and
Set to eSpeed.

Next, in step S3, it is determined whether or not the transfer speed of the host computer exceeds the optimum receiving speed of the printer. Only if it exceeds
Since this specific example is effective, the process ends if the value does not exceed the value. If it exceeds, step S4
To optimize the transfer speed, and set the optimized transfer speed to OptimumSpeed. This process is the same as in the first embodiment.

Next, in step S5, it is determined whether a device other than a printer is connected to the host computer. If a device other than a printer is not connected, the same settings as those in the first example may be used, and the process ends here. If a device other than a printer is connected, the process proceeds to step S6, and it is determined whether the connected device is in a usable state. If the printer is not usable, the process is the same as when only the printer is connected, and the process ends. In the usable state, the process proceeds to step S7, in which the optimized transfer speed within the range of the transfer speed of the host computer is increased in units of 100 kilobytes, and the value is set in the array SetSpeed [20].
Set to.

For example, assume that the transfer speed of the host computer is 1 megabyte per second, and the transfer speed of the optimized printer is 400 kilobytes per second. In this case, the optimized speed increased by 100 kilobytes is set in order from SetSpeed [0] in the array. The setting contents are shown below. SetSpeed [0] = OptimumSpeed + 100 = 500 [KBytes / S] SetSpeed [1] = OptimumSpeed + 200 = 600 [KBytes / S] SetSpeed [2] = OptimumSpeed + 300 = 700 [KBytes / S] SetSpeed [3] = OptimumSpeed + 400 = 800 [KBytes / S] SetSpeed [4] = OptimumSpeed + 500 = 900 [KBytes / S] SetSpeed [5] = OptimumSpeed + 600 = 1000 [KBytes / S] The equation below SetSpeed [6] is Ignore it because it will be faster than the transfer speed of the host computer.

FIG. 31 is a flowchart for resetting the transfer speed in the seventh embodiment. First, in step S1, the timer 46 of the port driver 7 shown in FIG. 27 is started. Then, in step S2, the data transfer is started with the transfer speed set to the previously determined optimum speed. In step S3, the timer 46 is stopped when data of a specific number of bytes has been transferred. Then, the value at that time is set in Time.

Next, in step S4, the current transfer rate is calculated from the transferred data size and the timer value.
Set to RealSpeed. That is, actually start the transfer,
The transfer rate is measured using the timer 46. And
In step S5, it is determined whether or not the actual transfer speed is smaller than a value obtained by subtracting 100 kilobytes from OptimumSpeed set as the optimum transfer speed. Here, it is determined whether or not the actually measured speed is actually lower than the optimum speed.

When a simple numerical comparison is made, the measurement error is included, so that the data transfer is performed at almost the optimum speed, but the data transfer is corrected. Therefore,
Here, considering the accuracy of the timer 46, 10
The value obtained by subtracting 0 kilobytes is compared with the speed actually measured. If the actual speed is lower than this, there is no error, so the data transfer speed is corrected. That is, the process proceeds to step S6, where the optimum speed is compared with the actual speed, the optimum speed is corrected, and the corrected speed is set again.

In this case, which setting should be performed is calculated by the following equation. Array number = (OptimumSpeed / RealSpeed) / 100-1 The equation of the array number shown here is selected from the SetSpeed array group, and the transfer speed is reset as the optimum speed. That is, data transfer is performed in a standby time according to the condition.

Thus, the processing of steps S1 to S6 is repeated as necessary, and the processing is terminated when the optimum transfer speed and the actual transfer speed become substantially equal. Next, the process proceeds to step S7, where the remaining data is transferred. That is,
In steps S1 to S6, the transfer speed is corrected and the remaining data is transferred. For example, the actual transfer rate measured as described above is 30 per second.
Assuming 0 kilobytes, the array number i is obtained by the following equation. i = (400−300) / 100−1 = 0

Therefore, in this example, the optimum speed for the next resetting is SetSpeed [0] = 500 [KBytes / s]. At first, the transfer speed set to 400 kilobytes per second was reduced to 300 kilobytes due to parallel processing with other devices. If this is reset to reduce it to 500 kilobytes per second, the transfer speed at that time is 500 × 3
00/400 = about 380 KByte / s. That is, as a result, data transfer can be performed at a speed close to the optimum receiving speed of the printer.

<Effects of Specific Example 7> As described above, when a plurality of external devices are connected to the host device and the apparent data transfer rate to the external device to which data is to be transferred is reduced, each external device is connected. Sending data to the device at the same time,
By measuring the apparent transfer rate and reducing the standby time so that the transfer rate approaches the target transfer rate, the data transfer rate for each external device can be optimized.

<Specific Example 8> In the specific example described above, the host device was powered on while a plurality of external devices were connected to the host device, and thereafter, the connection state did not change during data transfer to the printer. However, for example, PCMC
By using an interface such as an IA connection, an external device can be freely connected and disconnected while the host computer is operating. Therefore, when an external device is newly connected to the host computer and starts bidirectional communication with the host computer while the print data is being transferred to the printer, the substantial data transfer speed to the printer fluctuates.

FIG. 32 is a flowchart showing a process at the time of power-on in the eighth embodiment. When the host computer is powered on, this process starts first. Steps S1 to S3 in the figure are the same as in the case of the specific example 7 described with reference to FIG. The same applies to step S4, in which the optimum transfer speed obtained by measurement is first set.
Then, in step S5, it is determined whether or not PCMCIA is supported. Except for the case where PCMCIA is supported, the processing is the same as that of the specific example 7, and thus the processing ends.

If PCMCIA is supported, the flow advances to step S6 to increase the optimum receiving speed set within the range of the transfer speed of the host computer in units of 100 kilobytes, and the array SetSpe
Set to ed [20]. The contents of the sequence are exactly the same as in Example 7.

FIG. 33 is a flowchart for resetting the transfer rate in the eighth embodiment. Here, while data is being transferred to the printer, the data transfer speed is monitored to detect a decrease in the data transfer speed due to a new connection of another external device.
First, in step S1, the data transfer unit 12 of the port driver 7 shown in FIG. 27 receives the transfer data size. Then, in step S2, the transfer rate is set in the loop counter 17 as the optimum transfer rate. Next, in step S3, the timer 46 is started. In step S4, one-byte data is transferred. In step S5, the transfer data size is decremented. Then, in step S6, it is determined whether or not the transfer data size has become "0".

If there is still data to be transferred,
Proceeding to step S7, it is determined whether the printer is busy. If the printer is busy, the timer 46 is temporarily stopped. This is to exclude a time during which the printer cannot transfer data while the printer is busy because the time being checked by the timer is the data transfer time of the host computer.
In step S9, it is determined whether the printer is busy,
If the printer is no longer busy, proceed to step S10 to restart the timer.

In step S11, it is determined whether data of a specific number of bytes has been transferred. Then, in step S12, the timer 46 is stopped, and the value at that time is
Set to Time. In step S13, the current transfer rate is calculated from the transfer data size and the timer value,
Set to Speed. This step S12, step S
The processing of 13 and the like is the same as the processing of step S4 of the specific example 7.

As described above, the actual transfer speed is obtained by calculation, and in step S14, the actual calculation speed is compared with the set optimum speed. The method of calculating the actual calculation speed and the method of comparison with the set speed are the same as in the seventh embodiment. Therefore, if the actually measured speed is lower than the set speed, the process proceeds to step S15, and the set speed is reset. The resetting method is the same as in the seventh embodiment.

<Effect of Specific Example 8> As described above, while the power supply of the host computer is turned on, the lowering of the transfer rate is monitored, and the external device newly connected to the host computer is recognized. When the external device performs the parallel operation, the transfer speed is reset. In this way, the transfer speed can be optimized so that the printer does not overrun or lose data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system of a specific example 1.

FIG. 2 is a diagram illustrating a difference in transfer speed depending on the performance of a PC (personal computer).

FIG. 3 is a printer operation time chart when the data transfer speed is appropriate.

FIG. 4 is a printer operation time chart when the data transfer speed is inappropriate.

FIG. 5 is a system operation flowchart of the first embodiment.

6 is a flowchart for obtaining an apparent transfer speed in steps S3 and S4 in FIG. 5,
(A) is a flowchart of a calculation operation of the transfer speed TransSpeed1, and (b) is a flowchart of a calculation operation of the transfer speed TransSpeed2.

FIG. 7 is an explanatory diagram of calculation of a transfer rate reduction rate.

FIG. 8 is a flowchart of a data transfer operation of the port driver 7 shown in FIG.

FIG. 9 is a system operation flowchart of a specific example 2;

FIG. 10 is an explanatory diagram of an error of a weight counter.

FIG. 11 is a flowchart of an error correction operation.

FIG. 12 is an operation flowchart in the case of performing correction by lowering a counter.

FIG. 13 is a flowchart of an operation in a case where correction is performed by increasing a counter.

FIG. 14 is a block diagram illustrating a system configuration of a specific example 3.

FIG. 15 is an explanatory diagram of a system operation of a specific example 3.

FIG. 16 is a block diagram showing a system of a specific example 4.

FIG. 17 is an explanatory diagram of data loss due to rounding of a signal line and a preventive measure.

FIG. 18 is an operation flowchart of a transfer speed adjustment process.

FIG. 19 is a flowchart (part 1) of a signal line rounding adjustment process;

FIG. 20 is a flowchart (part 2) of a signal line rounding adjustment process.

FIG. 21 is a flowchart of a data receiving unit processing outline.

FIG. 22 is a block diagram showing a system of a specific example 5;

FIG. 23 is an explanatory diagram of an optimization method in the specific example 5.

FIG. 24 is a schematic flowchart of a reception speed adjustment process of Example 5;

FIG. 25 is a timing chart of an optimization method in the specific example 6.

FIG. 26 is an operation flowchart of a specific example 6.

FIG. 27 is a block diagram showing a system according to Example 7;

FIG. 28 is an explanatory diagram of a state of connected devices in the specific example 7.

FIG. 29 is an explanatory diagram of the amount of data transferred to the printer in one second.

FIG. 30 is a processing flowchart when power is turned on in Example 7;

FIG. 31 is a flowchart of resetting the transfer speed in Example 7;

FIG. 32 is a processing flowchart when power is turned on in a specific example 8.

FIG. 33 is a flowchart for resetting the transfer speed in specific example 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Host computer 3 Printer 4 Application 5 Operating system 6 Printer driver 7 Port driver 23 Data analysis part 24 Printing part 30 Data reception part

Claims (9)

[Claims] 1. A host device comprising: a host device; and an external device for receiving data from the host device. The host device includes: a transfer speed adjusting unit for adjusting a transfer speed of the data; A wait processing unit that controls so as to wait for transfer for a predetermined standby time every time data is transferred, wherein the transfer speed adjustment unit transmits a predetermined amount of dummy data to a given amount before transferring the data. Measure the apparent transfer speed when transferring in the standby time, and from the relationship between the apparent transfer speed and the standby time,
A data transfer system, wherein the standby time suitable for the external device is selected. 2. The data transfer system according to claim 1, wherein the transfer speed adjustment unit measures an apparent transfer speed when a predetermined amount of dummy data is transferred with different standby times, and the apparent transfer speed is measured. A data transfer system for determining a change in the transfer speed and selecting the standby time suitable for the external device. 3. The data transfer system according to claim 1, wherein the transfer speed adjustment unit measures an apparent transfer speed when a predetermined amount of dummy data is transferred for a selected standby time. A data transfer system that detects an error from a target data transfer speed and corrects the standby time. 4. The data transfer system according to claim 1, wherein said transfer rate adjusting section measures an apparent transfer rate by using a timer provided on an external device side. system. 5. The data transfer system according to claim 1, wherein the transfer speed adjustment unit checks whether or not data loss has occurred when a predetermined amount of dummy data has been transferred for a selected standby time. A data transfer system, wherein when the disconnection occurs, the standby time is partially adjusted. 6. A host device and an external device for receiving data from the host device, wherein the external device includes: a reception speed measuring unit for measuring the data reception speed; and a measured reception speed for the data. And adjusting the time for enabling the busy signal for suppressing data transmission by the host device every time a predetermined amount of data is received so that the data reception speed approaches the optimum reception speed. A data transfer system comprising a reception speed adjustment unit. 7. The data transfer system according to claim 1, wherein the external device is provided with a direct memory access controller for automatically receiving data from a host device; A data transfer system, wherein a waiting time is inserted every time an amount of data that can be received collectively by a direct memory access controller is received. 8. The data transfer system according to claim 1, wherein when data is transferred from the host device to a plurality of external devices, the transfer speed adjustment unit transmits the data to the plurality of external devices simultaneously, A data transfer system comprising: actually measuring an apparent transfer speed; and reducing the standby time so that the transfer speed approaches a target transfer speed. 9. The data transfer system according to claim 8, wherein when the number of external devices connected to the host device and simultaneously transferring data increases or decreases, an apparent data transfer speed for each external device is monitored, and the apparent data transfer speed is monitored. When the data transfer rate changes, the standby time is reduced so that the transfer rate approaches a target transfer rate.