JP3394717B2 - Data transfer system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transfer system which optimizes a transfer speed when transferring data 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 this 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 is full, requests the printer driver to suspend the transfer.

When printing progresses and the printer buffer becomes empty, data is transferred again from the printer driver. In addition to print control of the printer, when transferring data from the host device to various external devices, such procedure control is generally performed.

[0004]

By the way, the above conventional techniques have the following problems to be solved.
For example, consider a case where a personal computer is a host device and print data is transferred to a printer. In recent years, the processing speed of the CPU (central processing unit) in personal computers has been remarkably improved. Therefore, the CPU
Due to the difference in performance between the two, the number of cases in which the data transfer rates are significantly different is increasing. 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 difference in operation speed may exceed the allowable range.

The printer does not need to receive data at a speed higher than a predetermined speed in consideration of the print speed and print quality of the printer engine. Rather, when data is transferred to the printer at high speed, the processor of the printer is overloaded for data transmission and reception, which may cause problems such as data loss and underrun 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 a high performance personal computer,
Development of a method for controlling a conventional printer normally is required. These problems similarly occur when data is transferred from the host device to various external devices.

[0006]

The present invention adopts the following constitution in order to solve the above points. <Structure 1> According to the present invention, in a data transfer system including a host device including a data transfer unit that transfers unit amount data to an external device each time a standby time elapses, the host device holds a predetermined amount of dummy data. The dummy data storage unit and the dummy data in the dummy data storage unit are supplied to the data transfer unit,
A unit amount of dummy data is transferred from the data transfer unit to an external device at each set waiting time, and the transfer time required from the start to the end of the transfer of dummy data is measured by a timer, and the transfer time and the transfer amount of dummy data are A transfer rate adjusting unit that calculates the transfer rate of the dummy data from this, and calculates a standby time for matching the transfer rate with the optimum data receiving rate of the external device that holds the transfer rate in advance, and a standby time setting unit that sets the calculated standby time And are included.

[0007] <Configuration 2> Te data transfer system smell according to Structure 1, transfer rate adjusting section calculates the transfer rate when transferring with different settings <br/> waiting time each dummy data of a predetermined amount The standby time is calculated from the change in each transfer rate.

<Structure 3> In the data transfer system according to Structure 1, the transfer speed is
The adjustment unit uses a timer provided on the external device side to control the transfer time.
The feature is that it is actually measured by using.

<Structure 4> In the data transfer system according to Structure 1, an external device
Is a sum check that counts the number of units of dummy data received
It has a processing unit, and the transfer rate adjustment unit
ー The number of data transmission and the unit amount dummy data received from the external device
Inspect for data loss by comparing with the number of data received
However, if data loss occurs, the calculated waiting time
Is partially adjusted.

<Structure 5> In the data transfer system according to Structure 1, the host device
Transfer from a storage device to multiple external devices
The speed adjustment unit simultaneously writes dummy data to multiple external devices.
Transfer and calculate each new transfer speed, the new transfer speed
Characterized by shortening the waiting time so as to approach the transfer speed
And

[0011] In <Configuration 6> data transfer system according to Structure 5, when an external device for transferring data simultaneously connected to the host device is increased or decreased, to monitor a new transfer rate for each external device, the new When the transfer rate changes, the waiting time is shortened so that the new transfer rate approaches the transfer rate.

[0012] <Configuration 7> the time to receive a busy signal from an external device and waiting time, in a data transfer system having a host apparatus for transferring a unit amount data to the external device whenever the waiting time elapses, the host device, The external device includes a dummy data storage unit that holds the dummy data and a data transfer unit that transfers the unit amount dummy data of the dummy data storage unit to the external device each time the standby time elapses. And the reception speed measurement unit that calculates the reception speed of the dummy data from the time required for reception, the reception speed adjustment unit that calculates the waiting time for matching the reception speed with the maximum reception speed of your own, and the calculated waiting time. A waiting time setting unit for setting is provided, and a busy signal is supplied to the host device only during the waiting time when data is received.

[0013] In <Configuration 8> structure 7 a data transfer system according to the external device, the direct memory access controller to automatically receive data from the host device is provided, receiving the speed adjustment unit of the external device, a direct memory access The controller detects the quantity of unit quantity data that can be received collectively,
A feature is that a new waiting time is calculated by multiplying the calculated waiting time by the quantity.

[0014]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to 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 the case of transferring data from the host device to various external devices, but here, the case of transferring data 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
It is a parallel interface standardized by s).
The host computer 1 is provided with an application (AP) 4 that generates print data, an operating system (OS) 5, a printer driver 6, a port driver 7, and an IEEE1284 output unit 8.

The printer 3 is various well-known printing devices such as an electrophotographic printer and an inkjet printer. The port driver 7, as shown in this figure,
The I / F processing unit 11, the data transfer unit 12, the transfer speed adjustment unit 13, the timer 14, the counter generation unit 15, the dummy data 16, the loop counter 17, and the wait processing unit 18 are included.

In this system, the host computer 1
Has a high-speed processor, and the data transfer rate of the printer driver 6 is extremely high. Therefore, if the printer 3 is left as it is, there is a risk that the printer 3 may cause underrun or data loss. Therefore, 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 the I / F processing unit 1
1 and the data transfer unit 12 and sent to the IEEE1284 output unit 8. The transfer rate adjusting unit 13 shown in the figure is an I / F
It is a part having 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 the 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, first, a fault occurring in the printer 3 due to a difference in transfer speed will be specifically described. FIG. 2 is an explanatory diagram showing a difference in transfer speed depending on the performance of a PC (personal computer). In (a) of the figure, for example, the data transfer rate is 6 per second.
00 kilobytes of host computer 1 to printer 3
A case of transferring data to (here, a laser printer) is shown. The operating clock of the processor in this case is 100 MHz per second. (B) shows a case where data is transferred from the host computer 1 having a data transfer rate of 1 megabyte per second to the printer 3. The operating clock of the processor is 100 MHz per second. Note that (a)
Uses the PCI bus for 32-bit processing, and (b) has 16
The difference is that the processor uses a VL bus for bit processing.

(C) is also a processor of 16-bit processing, and shows an example in which the data transfer rate is 300 kilobytes per second. In this case, the operating clock of the processor is 66 MH
z. Further, (d) shows an example in which the data transfer rate is 400 kilobytes per second for a 16-bit processing processor. The operating clock of this processor is 66 MH
z. Both buses use the VL bus.

Recently, a processor having an operating clock of 200 MHz to 400 MHz has also appeared. For example, consider a case where the user connects personal computers having various performances as shown in the figure to the same printer 3 or print requests are made from various personal computers through a network. In this way, when the frequency of the operating clock of the processor is extremely high, the printer driver also operates at high speed, and the printer 3 is loaded with the following load.

FIG. 3 shows a printer operation time chart when the transfer speed is appropriate. The printer normally receives print data, analyzes the print data, and prints while controlling the printer engine. Therefore, as shown in this figure, it is preferable that the processes of receiving, analyzing, and printing are alternately repeated regularly.

FIG. 4 shows a printer operation time chart when the data transfer rate is inappropriate. Normally, in a printer, reception processing has priority over analysis processing. That is,
If data is received during data analysis, the receiving process is prioritized. Also, the printing process is prioritized over the analysis process. This is because the drive of the print head, the spacing of the printing paper, etc. must be controlled at a constant speed without delay.

However, for example, as shown by an arrow A in this figure, if the next data is received from the host side before the print data is received and the analysis process is started, the reception process is prioritized by an interrupt. Will be done. Therefore, the analysis process is postponed to the reception process, 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 the analysis process is delayed, the data cannot be supplied to the printer engine in time. Therefore, blank printing is performed from the middle without supplying the print data. These problems occur when there is data transfer from the host computer at a data transfer rate that far exceeds the printer's required reception rate. Therefore, in this specific example, the data passed from the printer driver 6 by the port driver 7 shown in FIG.
When transferring 1 byte at a time to the printer 3, a certain waiting time is inserted every time 1 byte is transferred. By thus waiting for data transfer, the overall apparent transfer rate is reduced. In this way, the data transfer rate is optimized. In another specific example, a busy signal for suppressing data transfer is output on the printer side to reduce the apparent transfer rate.

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 receiving speed of the printer 3, etc.
It depends on various factors. Therefore, in this specific example, the transfer rate 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 transfer of the print data, and the predetermined waiting time is set. Measure the transfer rate at that time. Depending on this result,
Calculate the waiting time to optimize the apparent transfer rate. The waiting time is set in the loop counter 17 shown in FIG. The wait processing unit 18 controls the data transfer unit 12 so as to wait for the data to be transferred for the set waiting time each time one byte is transferred. Hereinafter, the operation of the system according to the first specific example will be sequentially described with reference to the flowchart.

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

FIG. 5 shows a system operation flowchart of the first specific example. This flowchart shows the operation of the port driver 7. First, in step S1 in the figure, the transfer rate adjusting unit 13 of the port driver 7 determines that the I / F
The set 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 rate required by the printer. In addition, SetSpeed, DummySize, Count1,
TransSpeed, Count2, and TransSpeed2 are all names indicating variables to which data is set when arithmetic processing is executed. In step S2, the dummy data 16 is read and its size is set in DummySize. In the next step S3, the wait counter is Count
When the value is 1, the transfer speed TransSpeed1 is calculated. This wait counter is a counter used when actually measuring the transfer rate, and holds a waiting time for waiting for transfer each time one byte is transferred.

TransSpeed1 obtained in step S3 is an apparent transfer speed when the waiting time is Count1.
In step S4, the apparent transfer rate TransSpeed2 when the waiting time is Count2 is obtained. The values Count1 and Count2 of the wait 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 steps S3 and S above.
4 shows a flowchart for obtaining an apparent transfer rate in No. 4. (A) is a flowchart of a calculation operation of the transfer speed TransSpeed1. (B) is the 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 wait counter. Next, in step S2, the timer 14 is started. The timer 14 is composed of a digital counter or the like. For the data transfer unit 12, dummy data 16, dummy data size DummySize, and wait counter value Count1
To issue a data transfer command.

The data transfer unit 12 includes a transfer speed adjusting unit 13
The value set in the wait counter each time 1-byte dummy data is transferred using these values received from
Wait for the transfer for Count1 and transfer all dummy data. When the transfer of the dummy data 16 for the dummy data size DummySize is completed, in step S5, the timer 1
Stop 4 and set the timer value at that time 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 rate TransSp
Calculate eed2. The calculation formula is as follows. TransSpeed1 (when the wait counter value is Count1) = Time1 / DummySize (1) TransSpeed2 (when the wait counter value is Count2) = Time2 / DummySize (2)

Next, the process proceeds to step S5 in FIG. 5, and the two types of obtained apparent transfer rates TransSpeed1 and TransS are obtained.
peed2 and the counter value Co when measuring the transfer rate
From unt1 and Count2, the decrease rate Dec of the transfer rate when the counter is increased by "1" is calculated.

FIG. 7 shows an explanatory diagram of this transfer rate reduction rate calculation. The horizontal axis shown in this figure shows the value of the wait counter, and the vertical axis shows the actually measured apparent transfer rate. As shown in the figure, point P when the wait counter value Count1 is set and the apparent transfer rate is measured, and point Q when the wait counter value Count2 is set and the apparent transfer rate is measured. By connecting and with 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 rate when the value of the wait counter is decreased by "1". This formula is (1) below
It is as shown in the formula. Dec = | TransSpeed1-TransSpeed2 | / | Count1-Count2 | = | Transfer speed 1-Transfer speed 2 | / | Wait counter 1-wait counter 2 | ... (3)

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

First, the letter size paper has a length of 11 inches and a width of 8.5 inches. The maximum data size for printing on this paper is 11 x 600 x 8.5 x 6
00 = 33660000 (bits). That is, the data size is about 4 megabytes. When this data is printed at the above speed, 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 rate is set higher than this value, and data is intermittently received. The set value of the data transfer rate of the host computer is set in SetSpeed as already described. At this time, the wait counter Count1
Using the apparent transfer rate TransSpeed1 and the reduction rate Dec, the equation 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 operating 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 dummy data is 64 kilobytes. Transfer time Time when the wait counter Count1 is set to "1"
1 is 130 ms, and the transfer speed at this time is TransSpeed
1 became 480 kilobytes / second according to the above formula (1).

The wait counter Count2 is set to "1".
Transfer time Time2 when set to 0 "is 320 ms,
The transfer speed TransSpeed2 has become 200 kilobytes / second according to the 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 /
The value of the loop counter is calculated from the above results by 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", the data can be transferred at SetSpeed, that is, the optimum transfer speed required by the printer. An actual data transfer operation example using this loop counter will be described below.

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

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

In the above example, the rate of decrease in the transfer rate was calculated based on the difference in the apparent transfer rates when the transfer was performed with different waiting times. It doesn't matter.

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

The data transfer process can be applied to not only the data transfer to the printer but also the data transfer to various external devices. Also, since the data transfer rate is 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 interface configuration, and the printer buffer size can be accurately measured. Therefore, the transfer rate can be optimized by measuring

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

FIG. 9 shows a system operation flowchart of the second specific example. This is an improvement of step S5 and subsequent steps of the system operation of the specific example 1 shown in FIG. Therefore, the processing from step S1 to step S4 shown in FIG. 5 is the same as that of the first specific example, and illustration thereof is omitted. In step S1 of FIG. 9, the decrease rate Dec of the transfer rate when the counter is increased by “1” is calculated in the same manner as in the first specific example.

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

FIG. 10 shows an error explanatory diagram of the wait counter. Similar to FIG. 7, the vertical axis of the graph represents the transfer rate and the horizontal axis represents the value of the wait counter. In the specific example 1, the relationship between the transfer rate and the wait counter is approximated by a straight line like the broken line in the figure. However, when the dummy data is actually transferred using the loop counter obtained by the calculation as the wait counter and the result is plotted, the relationship between the transfer speed and the wait counter is slightly curved 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 as indicated by the broken line as in the first embodiment, the actual transfer speed becomes SS1. Therefore, step S4 of FIG.
As shown in, the loop counter value is corrected in consideration of the difference between the actually measured transfer rate SS1 and the target transfer rate SetSpeed. The data transfer already described is performed using the loop counter value after this correction (step S in FIG. 9).
5).

FIG. 11 shows a flowchart of this error correction operation. First, in step S1, the dummy data 16 shown in FIG. 1 is read and its size is set to DummyS
Set to ize. Next, in step S2, the value of the loop counter is set in the wait counter Count3. This is a value corresponding to C1 in FIG. Then, in step S3, the timer is started. In the next step S4, dummy data, dummy data size, data such as a wait counter, etc. are passed to the data transfer unit 12, and a data transfer instruction is issued. Data transfer unit 12
Uses the received value to set the waiting time C1
Only while waiting for the transfer, the dummy data is transferred.

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 to 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 the transfer speed thus obtained is equal to or lower than the optimum transfer speed SetSpeed of the target printer. If the measured transfer rate 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 and the counter is decremented and corrected.

FIG. 12 shows an operation flowchart when the counter is down and corrected. First, step S
In 1, set the value of the loop counter that has an error to CtrCount.
Set to 1. Next, in step S2, the dummy data is read and its size is set in DummySize. Then, in step S3, the value of the loop counter is decremented by 1 and set in the wait counter (step S4). In step S5, a timer is started.

Then, in step S6, the data transfer rate based on the value of the wait counter is measured 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 or not the data transfer rate exceeds the target value. If it does not exceed, the process returns to step S3 again to further decrease the value of the wait counter. In this way, the process of steps S3 to S8 is repeated while the value of the wait counter is decreased until the target value is exceeded.

When the value exceeds the target value, the process proceeds to step S9, and the value of the wait counter is decremented 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. Compared with the process shown in FIG. 12, the only difference is that the value of the wait counter is incremented by “1” at step S3. When the value of the wait counter reaches the target value, that value is set in the loop counter 17 as in the case of FIG. In this way, in any case, the actual measurement is repeated until the value of the loop counter approaches the target value to optimize the transfer rate.

The processes shown in the specific examples 1 and 2 may be automatically performed before the start of printing. For example, it is preferable that the control program is automatically started when the host computer and the printer are connected and the power of the printer is turned on. Further, the process may be started at an arbitrary timing according to an instruction from the operator.

<Effect of Concrete Example 2> By the above processing, when the host computer having a high-speed operation clock is connected to the printer, the transfer rate is optimized by the arithmetic processing and the transfer rate is actually measured. Therefore, it becomes possible to bring the transfer rate closer to the optimum value.

<Specific Example 3> In the specific example 3, an example in which the speed is adjusted so that the accuracy of the required data transfer rate is within an error of several tens of kilobytes per second or less. In the above example, the apparent transfer rate is measured using the timer 14 provided in the port driver 7 of the host computer 1. However, the printer 3 may be provided with a timer with higher accuracy than the host computer side. In such a case, the transfer rate can be optimized with high accuracy by measuring the apparent transfer rate on the printer side instead of the host computer side.

FIG. 14 is a block diagram showing the system configuration of the third specific example. The host computer 1 in the figure has the same configuration as that of the first specific example. The same parts of both are denoted by the same reference numerals. 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 in the figure includes a data receiving unit 20,
A data analysis unit 23 and a printing unit 24 are provided. The data receiving unit 20 is provided with a receiving unit 21 that receives data transferred from a host computer, and a timer 22 having the same role as that of measuring the data transfer rate in the first specific example.

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

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

Next, in step S3 of FIG. 15, dummy data, dummy data size, wait counter, etc. are passed to the data transfer section 12 to issue a data transfer instruction. In step S4, the value received by the data transfer unit 12 is used to transfer the dummy data while using the waiting time set in the wait counter. This dummy data is received by the printer as shown in step S9 of 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, the timer 22 is stopped when the data transfer command is received, 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 Time6. After that, the apparent transfer rate is calculated from the dummy data size and the timer value (steps S6 and S).
7).

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

Normally, most of the timers of the host computer 1 have an accuracy of several tens of milliseconds, and the loop counter 17
The standby time set to includes an error of several tens of millimeters. For this reason, when the required accuracy of the transfer rate is high, it becomes difficult to satisfy the accuracy. On the other hand, if the accuracy of the timer 22 (FIG. 14) of the printer 3 is about several microseconds, the apparent transfer time can be measured with sufficient accuracy.

<Effect of Concrete Example 3> When high accuracy is required for the data transfer rate, a more accurate transfer rate can be optimized by using a timer on the printer side. Other effects are the same as those of the first specific example.

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

FIG. 16 is a block diagram showing the system configuration of the fourth specific example. The host computer 1 in the figure has the same configuration as that of the first specific example. The same parts of both are denoted by the same reference numerals. In addition, the port driver 7
A high counter 26 and a low counter 27 are provided. This is because two types of waiting times are set in advance and the apparent data transfer rate in each case is measured. The printer 3 is newly provided with a sum check unit 28 that counts and totals the number of bytes of received data.

The interface cable for 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 to 6 are used as dummy data.
Use 64 kilobytes of data between 5535. 1
This is because the content of data flowing through the signal line is changed each time a byte is transferred, and data loss due to rounding is monitored.

FIG. 17 is an explanatory view of data loss due to rounding of the signal line and a preventive measure. In the figure, (a) shows a state in which 8-bit data is serially transferred. It is assumed that the signal level of any one of the signal lines changes at the timing shown in this figure. (B) is a strobe for notifying the timing for receiving data on the printer side. This strobe is also transferred to the printer through the interface cable together with the data.

In the printer, each data is taken into the reception buffer at the timing when the strobe level rises from the low level to the high level and the timing when the strobe level falls from the high level to the low level. In the illustrated example, time t1
The first data is fetched at, the next data is fetched at time t2, and the last data is fetched at time t3. When the strobe signal is rounded, the following state occurs.

(C) is the same data as (a).
(D) is a strobe. This strobe is blunted at the timing from time t1 to t2 shown in the figure. Time t when this n strobe becomes low level
At 1, the first data is fetched, and when the n strobe becomes high level next, the next data is fetched. However, since the signal is rounded, if the data is to be taken in at the time t2 when the high level is reached, the next data is already input and one data loss occurs.

According to the present invention, in order to prevent such a problem, the data transfer speed is partially adjusted at the portion where the data is likely to be rounded. (E) shows the content of the data 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 period 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, the wait time by the wait counter is inserted for T time to prevent the data loss. The specific operation will be described below with reference to a flowchart.

FIGS. 18, 19 and 20 are flowcharts for explaining the operation of the fourth specific example. First, Fig. 1
In step S1 of 8, the reduction rate Dec of the transfer rate is calculated as described in the above specific examples. Then, in step S2, the transfer rate is set to the transfer rate 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 that sets a waiting time when the strobe shown in FIG. 17 is at a high level. The low counter 27 is a counter that sets a waiting time when the strobe shown in FIG. 17 is at a low level. Therefore, two types of waiting time are used depending on the state of the strobe. Step S
In 3, the dummy data 16 is read and its size is set in DummySize.

Next, the blunt confirmation command is transferred to the printer 3. That is, the printer is notified to confirm the occurrence of the rounding while transferring the dummy data.
In step S6, the transfer rate adjusting unit 13 passes the size of the dummy data 16 and the dummy data to the data transfer unit 12 and issues a data transfer command. In step S7, the data transfer unit 12 uses the received value to transfer the dummy data while waiting for the transfer at the value set in the row counter 27. When the transfer is completed, a data transfer end command is transferred to the printer 3 side in step S8.

In step S9, 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. If the number of data is counted and displayed as it is, the numerical value becomes large. Therefore, for example, only the lower bits 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 port driver 7 of the result. In step S10, the number of received data received from the printer 3 is compared with the dummy data size. Also, the sum check data received from the printer 3 and the sum check result of the dummy data calculated on the host computer side are respectively compared. Then, if either of them is different, the rounding of the signal line is adjusted. The rounding adjustment is performed by extending the waiting time and slowing the data transfer rate. The processing for this rounding adjustment will be described with reference to FIG.

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

Here, in step S1 of FIG. 19, the value of the row counter is set in the adjustment counter CtrCount1. In addition, the value of the high counter is set to the adjustment counter CtrCount
Set to 2. Next, in step S3, the command for confirming the roundness is transferred to the printer 3. Further, in step S4, the dummy data 16 is read and its size is set in DummySize. Next, in step S5, the dummy data is output to the 1-byte printer.
Then, in step S6, nStrobe is set to a high level (valid). In this way, the printer 3 is notified that one byte of data has been transferred.

Next, in step S7, the value CtrCount1 of the adjustment counter is set in the wait counter Count8. Then, in step S8, Count8 is decremented. Step S9 is a process of determining whether or not the time corresponding to the wait counter has elapsed when the strobe is at the high level. Thus, when the waiting time corresponding to Count8 has elapsed, the process proceeds to step S10,
Decrement the size of dummy data. This is to count the data to be transferred byte by byte and check whether all the 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 or not the transfer of all dummy data has been completed.

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

When this waiting time has elapsed, step S1
In step 7, the size of 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 until the dummy data size becomes “0”.

After that, the process advances to step S19 to notify the printer 3 of the end of the dummy data transfer. Step S20
Then, the printer 3 counts the number of data received, and notifies the transfer rate adjusting unit 13 of this. Further, the sum check data Check2 is notified to the transfer rate adjusting unit 13. In the next step S21 and step 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, respectively, and it is determined whether they match.

If they do not match, the process proceeds to step S25, where the value of the wait counter is changed. In this example, the standby time when the strobe is at the low level is shortened, and the standby time when the strobe is at the high level is sequentially extended. Therefore, the pulse waveform is modified as shown in FIG. 17 (f) to prevent data loss. And
The apparent data transfer rate is measured again by the waiting time. In this way, the waiting time in 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 set, 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 flow chart of the data receiving unit processing outline on the printer side in the above processing. In step S1, the sum check data is reset when the rounding confirmation measurement command is received. Then, 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.

By the above processing, the presence or absence of data loss is inspected by transmitting / receiving dummy data. If data loss occurs, the standby time is partially adjusted at a predetermined timing to optimize the data transfer rate. Try to change.

<Effects of Specific Example 4> As described above, the apparent data transfer rate is adjusted to the optimum value, and the predetermined timing is set when data loss occurs due to the signal line or other environmental conditions. Since the standby time is partially corrected by, the data transfer rate can be optimized and the reliability can be improved.

<Specific Example 5> In the above specific example, all the host computers have the function of adjusting the data transfer rate. In this specific example, a printer that receives data is provided with a function of adjusting the data transfer rate. In particular,
When the printer receives data, it outputs a busy signal to the host computer side 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, the host computer 1 includes an application 4, an operating system 5, a printer driver 6, a port driver 7, and an IEEE.
The E1284 output unit 8 and the like are provided. These configurations are
This is the same as the specific examples so far. In addition to the receiving unit 31, 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. A maximum reception speed value 37 is stored in the data receiving unit 30, and this value is set as the optimum reception speed of the printer.

The receiving speed measuring unit 33 is a unit for measuring the receiving speed of the data received by the receiving unit 31 from the host computer 1 in a number of bytes per unit time, for example. The reception speed adjustment unit 34 determines the maximum reception speed value 3
7 is a section for setting the optimum reception speed and performing control so that the actual reception speed approaches the optimum reception speed. Timer 3
6 is used to measure the actual data reception speed and the like. The wait counter 35 is a counter that sets a waiting time for waiting for data transfer each time 1-byte data is transferred, as described in the above specific examples. In the case of this example, it means a time for suppressing the data transfer rather than waiting for the data transfer.

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

FIG. 23 shows a method explanatory diagram of the transfer rate optimizing operation in the fifth specific example. (A) of the figure shows the timing of data transfer at the transfer speed of the host computer. (B) is an nStrobe signal (simply called a strobe as in the above description) that controls the timing for the printer to fetch the data. In this case, data is taken in at the rising timing of the strobe. (C) is a busy mode for periodically suppressing data transmission when the printer fetches data.
It is a signal. Normally, in this way, the busy signal becomes effective at the timing between the strobe rising parts,
Data transfer between the host computer and the printer is performed. However, if this transfer rate is too fast for the printer, in this specific example, the time during which the busy signal is valid (the time when it goes to the high level) is extended. The time during which this busy signal becomes valid determines the waiting time described so far.

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

FIG. 24 shows a flow chart of the receiving speed adjusting process of the fifth specific example. 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
When the number of data set in is received, timer 3
Stop 6 and set the value at that time to Time. The reception unit 31 passes the received data number DataSize and the timer value Time to the reception speed measurement unit 33. Number of received data DataSize
Is a predetermined value for calculating the data reception speed, and may be an arbitrary number.

In step S4, the reception speed measuring unit 33 calculates the reception speed from the received value and sets the calculated value as Sp.
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, the optimum reception speed is obtained based on the maximum reception speed value 37 and is set in the register OptimumSpeed provided inside the reception speed measurement unit 33.

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

As already described with reference to FIG. 23F, the time for making the busy signal valid (high level) is calculated and stored in the wait counter 35. This calculation is
The optimum reception speed OptimumSpeed is subtracted from the actual data reception speed Speed calculated as described above, and the difference is divided by the received data number DataSize. The result of this division is the waiting time. The time for setting the busy signal to the low level is delayed by this time, and the time for making the busy signal valid (high level) is extended. The result is set in the wait counter.

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

<Effects of Concrete Example 5> With the above, FIG.
As shown in (f), the time for which the busy signal is valid can be adjusted to optimize the reception speed. Further, this control can be performed by the data receiving unit on the printer side, unlike the specific examples up to now. Further, since the reception speed of the data transferred from the host computer can be optimized on the printer side, even when the transfer speed optimization function is not provided in the printer driver of the host computer, the effects like the specific examples described so far can be obtained. Obtainable.

<Specific Example 6> In this specific example, a direct memory access controller for automatically receiving data from a host device is used on the external device side. The direct memory access controller shall be capable of withstanding high-speed data transfer by the host device. However, when the direct memory access controller receives the receivable buffer in a receivable amount of data, the direct memory access controller temporarily stops its operation. 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 printer processes the data received from the host computer at a low processing speed, the same trouble as the 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 the direct memory access controller receives data that can be collectively received. The system configuration itself may be the same as that described with reference to FIG. 22, so its illustration is omitted.

FIG. 25 is a timing chart of the optimizing method in the sixth example. (A), (b) of the figure,
The timing shown in (c) shows the state when data is transferred from the host computer to the printer without performing any optimization processing. (A) is the data transfer timing, (b) is the nStrobe signal for fetching it,
(C) is a busy signal transmitted from the printer side to the host computer. The content of each signal is the specific example 5.
It is similar to the case of.

The following (d), (e), and (f) are shown to compare the control of the sixth specific example with the fifth specific example.
This is the same as (d), (e), and (f) of FIG.
That is, every time 1-byte data is received, the busy signal, which should be low level at time t1 and time t4, is extended by T time,
The reception timing of data to be received at the timings of time t2 and time t5 is shifted to time t3 and time t7. However, when the direct memory access controller is used, high-speed reception matching the transfer speed of the host computer is possible. The data thus received is stored in the buffer memory of the printer (not shown).

When the buffer memory becomes full, the printer reads 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 rate by the direct memory access controller can be brought close to the optimum transfer rate for printing by the printer.

(G), (h), and (i) show the control of the sixth embodiment. That is, since data transfer is performed by the direct memory access controller until time t8 in the figure, data is received at the transfer speed on the host computer side. Then, at this timing, the busy signal is extended by 3T and output from time t8 to time t11 as shown in the figure.
Therefore, the data transfer by the host computer is suppressed from time t8 to t11. By doing this, 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 collected together. This means that the time has passed from t8 to time t11. This allows
The case shown in (f) and the case shown in (i) have the same average data transfer rate in a sufficiently long period.

FIG. 26 shows an operation flowchart of the sixth example. First, in step S1, the size of data to be transferred is set in TotalSize. Next, in step S2, DMAStatusFlag is turned on. this is,
This is a step of determining whether or not preparation for DMA (Direct Memory Access Controller) processing is completed. In the default state, since this flag is off, the process proceeds to step S3 to inquire the DMA specifications, and the direct memory access controller sets the number of data that can be received at one time in DMASize. In step S4,
Turns 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. Then step S6
At, the 1-byte data is read from the memory and output. Regarding the DMA specifications, the host computer makes an inquiry to the printer and stores the DMA specifications in a buffer on the host computer side. DMAStatusFla
One g is set for each device, that is, for each external device connected to the host computer. This is to prevent the same external device from being repeatedly inquired about DMA information. This flag is queried and set when the external device is powered on and reset to off when the external device is powered off.

In the next step S7, the size of the data to be transferred, TotalSize, is decremented. This is because the remaining data is displayed when the 1-byte data is transferred. In step S8, it is determined whether this TotalSize is "0". If it is "0", the processing is terminated because all data transfer is completed. If not "0", the process proceeds to step S9, and the DMA decrements the number of receptions that can be received at one time.

In step S10, it is determined whether or not this has become "0". If not "0", step S
Returning to 6, the data transfer is repeated byte by byte. Then, when the DMA transfers the number of data items that can be received at one time, the process proceeds from step S10 to step S11. The value of the wait counter obtained in Example 6 is multiplied by DMASize, and this is set as a new value of the wait counter. That is,
If each byte is transferred and the wait time for the wait counter is set by the busy signal, the DMASize bytes that can be transferred at once by the direct memory access controller are collectively set as a new time. Using this, the control shown in (i) of FIG. 25 may be performed.

In the next step S12, the wait counter thus set is decremented and the waiting time is measured. That is, in step S13, it is determined whether or not this wait counter has become "0", and the waiting time is waited for the waiting time. Then, when the time for 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 is completed in this way, the operation ends.

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

<Effect of Concrete Example 6> While the data can be transferred in accordance with the performance of the direct memory access controller provided in the printer and the data can be transferred at high speed, the number of data which the direct memory access controller can receive at once is considered. However, since a fixed waiting time is inserted each time this amount of data is received, the transfer rate can be optimized as in the above-described specific examples. Further, unlike the cases of the concrete example 1 and the concrete example 5 in which the transfer speed is adjusted every time one byte is transferred, the control for waiting time is simplified, so that the load on the host device and the printer device can be reduced.

<Seventh Embodiment> FIG. 27 is a block diagram showing the system of the seventh embodiment. In this specific example, an example in which a plurality of external devices are connected to the host computer 1 is shown. FIG. 28 shows a specific state explanatory view of the 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, the printer 3
The control of the data transfer rate is different from 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 and 4C, an operating system 5, a printer driver 6, a port driver 7, an IEEE1284 output section 8, a network driver 43, a serial driver 44 and the like. There is. The network driver 43 is a driver that controls the hub 42 and the like. In addition, the serial driver 44 is the modem 4
It is a driver for controlling the first and the like.

The external structure of this system is shown in the following figure.
FIG. 28 is an explanatory diagram of states of connected devices in the specific example 7. In the illustrated host computer 40,
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 specific examples so far. The port driver 7 of the host computer 40 includes an I / F processing unit 11, a data transfer unit 12, a transfer speed adjusting unit 13, a counter generating unit 15, dummy data 16, a loop counter 17, a wait processing unit 18, and a timer 46. I have it. The basic function of each part of the port driver is almost the same as that described in the first specific example. The operation specific 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. 10A shows an example in which only the printer is connected to the host computer 40 and operated. The horizontal axis of this graph is time. The vertical axis represents the amount of data transferred per unit time. From time t1 to time t
Up to 2, data is transferred and printed at a predetermined constant data transfer rate. (B) shows the control when there is a device other than the printer for transmitting and receiving.

The amount of data transferred during the period from time t1 to time t2 in (a) is the same as the amount of data transferred from time t1 to time t in (b).
This corresponds to the amount of data transferred in the time up to 2. (B)
In this case, the printer is controlled from time t1 to time t2.
Only in 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 the modem 41, and network control is performed through the hub 42.

In such a case, when transferring the same amount of data as shown in (a) to the printer, more data must be transferred to the printer per unit time between time t1 and time t2. . Therefore, in order to rather large amount of data D1 from D2 of FIG, In the case of (b),
Transfer speed becomes faster. In the specific examples so far, the transfer rate is set without considering the connection of other external apparatuses, so that when a plurality of external apparatuses are simultaneously controlled, the data transfer rate becomes slower than expected. In this specific example, the transfer rate is optimized.

FIG. 30 shows a processing flowchart at the time of power-on of the seventh specific example. This process 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, the transfer rate adjusting unit 13 checks the optimum receiving speed of the printer after checking the transfer rate,
Set to eSpeed.

Next, in step S3, it is determined whether the transfer speed of the host computer exceeds the optimum reception speed of the printer. Only if it is above
Since this concrete example is valid, the processing is ended if the number is not exceeded. If yes, step S4
Go to, optimize the transfer rate, and set the optimized transfer rate to OptimumSpeed. This process is the same as in the first specific example.

Next, in step S5, it is determined whether or not a device other than a printer is connected to the host computer. If a device other than the printer is not connected, the same setting as that of the first specific example may be performed, and the processing is ended here. If a device other than the printer is connected, the process proceeds to step S6, and it is determined whether or not the connected device is in a usable state. If it is not in the usable state, it is similar to the case where only the printer is connected, and the process is ended. In the usable state, the process proceeds to step S7, where the optimized transfer rate within the range of the transfer rate of the host computer is increased in 100 kilobyte units, and the value is set in the array SetSpeed [20].
Set to.

For example, assume that the transfer rate of the host computer is 1 megabyte per second and the transfer rate of the optimized printer is 400 kilobytes per second. In this case, the optimized speed increased by 100 kilobytes is sequentially set from SetSpeed [0] of 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 formula below SetSpeed [6] is , Ignore it because it exceeds the transfer rate of the host computer.

FIG. 31 shows a transfer rate resetting flowchart of 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 transfer rate is set to the previously determined optimum rate and the data transfer is started. In step S3, the timer 46 is stopped at the time when a certain specific number of bytes of data are 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 Real Speed. That is, the transfer is actually started,
The transfer rate is measured using the timer 46. And
In step S5, it is determined whether the actual transfer rate is smaller than the value obtained by subtracting 100 kilobytes from Optimum Speed set as the optimum transfer rate. In addition, here, it is determined whether or not the actually measured speed is slower than the optimum speed.

If numerical comparison is simply performed, the measurement error is included, and therefore the data transfer is performed at almost the optimum speed, but the correction is made. Therefore,
Here, considering the accuracy of the timer 46, the optimum speed is 10
The value obtained by subtracting 0 kilobytes is compared with the actually measured speed. If the actual speed is lower than this, it is not an error, so the data transfer speed is corrected. That is, the process proceeds to step S6, the optimum speed is compared with the actual speed, the optimum speed is corrected, and this is set again.

In this case, the calculation as to which setting should be made is performed by the following equation. Sequence number = (OptimumSpeed / RealSpeed) / 100-1 The formula of the sequence number shown here is selected from the sequence group of SetSpeed, and this transfer speed is reset as the optimum speed. That is, the data transfer is performed with the waiting time according to the condition.

In this way, the processes of steps S1 to S6 are repeated as many times as necessary, and when the optimum transfer rate and the actual transfer rate become substantially equal, the process ends. Next, in step S7, the remaining data is transferred. That is,
The transfer rate is corrected in steps S1 to S6, and the remaining data is transferred. For example, the actual transfer rate measured as described above is set to 30
Assuming 0 kilobytes, the array element number i is calculated by the following equation. i = (400-300) / 100-1 = 0

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

<Effects of Concrete Example 7> As described above, when a plurality of external devices are connected to the host device and the apparent data transfer speed with respect to the external device targeted for data transfer decreases, Send data to the device at the same time,
By measuring the apparent transfer rate and shortening 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 above specific example, the host device is powered on in the state where a plurality of external devices are connected to the host device, and then the connection state does not change during data transfer to the printer. However, for example, PCMC
By using an interface such as IA connection, external devices can be freely connected or disconnected while the host computer is operating. Therefore, when the external device is newly connected to the host computer and the bidirectional communication with the host computer is started during the transfer of the print data to the printer, the substantial data transfer speed to the printer varies.

FIG. 32 shows a processing flowchart at power-on in the eighth specific example. When the host computer is powered on, this process is started first. Steps S1 to S3 in the figure are the same as the case of the specific example 7 described with reference to FIG. The same applies to step S4. First, the optimum transfer rate obtained by measurement is set.
Then, in step S5, it is determined whether or not the PCMCIA is supported. Since the process is the same as that of the specific example 7 except that the PCMCIA is supported, the process ends.

If PCMCIA is supported, the process proceeds to step S6, where the optimum receiving speed set within the range of the transfer speed of the host computer is increased in 100 kilobyte units, and the array SetSpe
Set to ed [20]. The contents of the array are exactly the same as in the case of Example 7.

FIG. 33 shows a transfer rate reset flow chart in the eighth specific example. Here, while transferring data 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, 1-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 becomes "0".

If there is still data to be transferred,
In step S7, it is determined whether the printer is busy. If the printer is busy, the timer 46 is suspended. This is because the time that the timer is investigating becomes the data transfer time of the host computer, so that the time when the printer cannot transfer in a busy state is excluded.
In step S9, it is determined whether the printer is busy,
If the printer is not busy, the process proceeds to step S10 to restart the timer.

In step S11, it is determined whether or not a specific number of bytes of data have been transferred. Then, in step S12, the timer 46 is stopped, and the value at that time is set to
Set to Time. In step S13, the current transfer rate is calculated from the transfer data size and the timer value, and the
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.

In this way, the actual transfer rate is obtained by calculation, and in step S14, the actual calculated rate is compared with the set optimum rate. The calculation method of the actual calculation speed and the comparison method with the set speed are the same as those in the specific example 7. 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 concrete example 7.

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

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of 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 rate is appropriate.

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

FIG. 5 is a system operation flowchart of specific example 1;

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

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

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 specific example 2;

FIG. 10 is an explanatory diagram of an error of the wait counter.

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

FIG. 12 is an operation flowchart when the counter is down and corrected.

FIG. 13 is a flowchart of an operation when a counter is incremented for correction.

FIG. 14 is a block diagram showing 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 transfer rate adjustment processing.

FIG. 19 is a signal line rounding adjustment processing flowchart (part 1).

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

FIG. 21 is a flowchart of a data receiving unit process 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 according to a specific example 5.

FIG. 24 is a schematic flowchart of a reception speed adjustment process of a specific example 5.

FIG. 25 is a timing chart of the optimization method in Concrete Example 6;

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

FIG. 27 is a block diagram showing a system of a specific example 7.

28 is a state explanatory view of connected devices in a specific example 7. FIG.

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

FIG. 30 is a processing flowchart at the time of power-on of the specific example 7.

FIG. 31 is a transfer rate resetting flowchart of Concrete Example 7;

FIG. 32 is a processing flowchart at power-on in the eighth specific example.

FIG. 33 is a transfer rate reset flowchart in Concrete Example 8;

[Explanation of symbols]

1 Host computer 3 printers 4 applications 5 Operating system 6 Printer driver 7 port driver 23 Data Analysis Department 24 Printing department 30 data receiver

Claims (8)

(57) [Claims] 1. A data transfer system including a host device comprising a data transfer unit for transferring unit amount data to an external device each time a waiting time elapses, wherein the host device holds dummy data of a predetermined amount. A storage unit and the dummy data in the dummy data storage unit are supplied to the data transfer unit, and the unit amount dummy data is transferred from the data transfer unit to the external device at each set standby time to transfer the dummy data. The transfer time required from the start to the end is measured by a timer, the transfer rate of the dummy data is calculated from the transfer time and the transfer amount of the dummy data, and the optimum transfer rate of the external device is held in advance. A transfer rate adjusting unit that calculates a waiting time for matching the data reception speed and a waiting time setting unit that sets the calculated waiting time are included. A data transfer system characterized by the following. 2. A data transfer system according to claim 1, wherein the transfer speed adjusting unit calculates the respective transfer rate when the dummy data of the predetermined amount was transferred at a different set waiting time, respectively, each of said transfer A data transfer system characterized in that the waiting time is calculated from a change in speed. 3. The data transfer system according to claim 1, wherein the transfer rate adjusting unit actually measures the transfer time by using a timer provided on an external device side. 4. The data transfer system according to claim 1, wherein the external device includes a sum check processing unit that counts the number of received unit amount dummy data, and the transfer rate adjustment unit includes a transmitted unit amount. The number of dummy data transmissions is compared with the number of received unit amount dummy data received from the external device to check for data loss. If data loss occurs, the calculated waiting time is partially A data transfer system characterized by adjusting manually. 5. 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 rate adjusting unit transfers the dummy data to a plurality of external devices at the same time. A data transfer system, wherein each new transfer rate is calculated, and the standby time is shortened so that the new transfer rate approaches the transfer rate. 6. The data transfer system according to claim 5, wherein when the number of external devices connected to a host device and simultaneously transferring data increases or decreases, the new transfer speed for each external device is monitored and the new transfer rate is monitored. Data transfer system, wherein the standby time is shortened so that the new transfer rate approaches the new transfer rate when the new transfer rate changes. 7. A data transfer system having a host device for transferring a unit amount data to the external device every time the standby time elapses when a busy signal is received from the external device, the host device comprising: A dummy data storage unit that holds dummy data; and a data transfer unit that transfers the unit amount dummy data of the dummy data storage unit to the external device each time a standby time elapses. A reception speed measuring unit that calculates a reception speed of the dummy data from a predetermined reception amount of data and a time required for the reception, and a reception speed adjusting unit that calculates a waiting time for matching the reception speed with the maximum reception speed of the self. And a waiting time setting unit that sets the calculated waiting time, and supplies the busy signal to the host device for the waiting time when data is received. A data transfer system characterized in that 8. The data transfer system according to claim 7, wherein the external device is provided with a direct memory access controller that automatically receives data from the host device, and the reception speed adjusting unit of the external device is A data transfer system characterized in that a direct memory access controller detects the quantity of unit quantity data that can be collectively received and multiplies the calculated waiting time by the quantity to calculate a new waiting time.