JPH0983709A - Image forming device and system and data transfer method for the image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit and receive the data signals with no influence of noises by changing the delay time against the switch timing of other signals according to the working interface. SOLUTION: A printer device 20 detects the fall (high level to low level) of the signal nSTROB that is outputted from a host computer 10, and the timing when the device 20 fetches the data on the signals DATA is increased from its least value with every transfer of data. Then the data latch timing when the device 20 latches the correct data is defined as the latch timing for the transfer of print data between the computer 10 and the device 20. Thus it is possible to control the data latch timing for the computer 10 and the device 20 via a Centronics interface and to secure the optimum data latch timing without requiring any operation of an operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and an image forming system including an image forming apparatus such as a printer and a host computer, and a data transfer method in the system.

[0002]

2. Description of the Related Art For example, a Centronics interface is known as an interface for connecting a computer and a printer. This Centronics
Data transfer between the host computer and the printer apparatus connected according to the interface specifications is performed by a DATA signal output from the host computer and a nStrobe signal which is a timing signal for capturing the DATA signal.
When the printer device receives the signal, the printer device transmits a response signal (nACK) to the signal to the host computer. In the printer device, the trailing edge of the nStrobe signal (nStrobe
The DATA signal output from the host computer is captured at the leading edge of the be pulse).

However, if the data (DATA) is taken in immediately after the fall of the nStrobe signal, the influence of the change in the nStrobe signal may affect the data signal as noise, and there is a risk that wrong data may be taken in. was there. Therefore, it is considered that the influence of noise can be avoided by delaying the timing of capturing this data after the falling edge of the nStrobe signal.

[0004]

However, the above-mentioned conventional example has the following problems.

The characteristics of the cable used for the Centronics interface connecting the host computer and the printer device are various, and as described above, the noise given to the data signal due to the level fluctuation of other signals affects. There are many different times. Therefore, the timing at which the printer device captures the DATA signal is set to nStr
Even if it is delayed from the fall of the obe signal, if the delay time is constant, the effect of noise can be prevented depending on the interface, but in some cases, a delay time longer than that of the delay time tube is required. Also comes out. Therefore,
In order to solve such a problem, it is necessary for the printer apparatus to delay the timing of capturing the data signal as much as possible.

However, if the data signal fetch timing is delayed in this way, the influence of noise is eliminated and the reliability of data transfer is improved. However, due to this delay time, the data transfer speed between the host computer and the printer device is increased. Will be reduced.

The present invention has been made in view of the above-mentioned conventional example. By changing the delay time from the switching timing of other signals according to the interface used, the influence of noise is eliminated and the data signal is eliminated. It is an object of the present invention to provide an image forming apparatus and an image forming system capable of transmitting and receiving data, and a data transfer method in the system.

It is another object of the present invention to provide an image forming apparatus and an image forming system capable of forming an image by transmitting a data signal while preventing the data transfer time from becoming long, and a data transfer method in the system. The purpose is to

Further, an object of the present invention is to provide an image forming apparatus and an image forming system capable of automatically determining an optimum data fetching timing and transmitting / receiving data between a data source and an image forming apparatus, and An object is to provide a data transfer method in a system.

[0010]

In order to achieve the above object, an image forming apparatus according to the present invention has the following arrangement.
That is, an image forming apparatus connected to a data source via an interface, the receiving unit receiving information from the data source via the interface, and the latch timing adjustment based on the information received by the receiving unit. Setting means for setting a mode; storage means for storing timing information in the latch timing adjustment mode; and, when the latch timing adjustment mode is set by the setting means, depending on the timing information stored in the storage means. Data receiving means for taking in the predetermined data transmitted from the data source, judging means for judging whether the taking of the predetermined data is normal, and data stored in the storage means when the judging means judges normal The timing information is the data acquisition timing of the receiving means. And a control unit.

In order to achieve the above object, the image forming system of the present invention has the following configuration. That is, an image forming system having a data source and an image forming apparatus that receives information from the data source to form an image, the data source transmitting information to the image forming apparatus via an interface. The image forming apparatus has means for setting a latch timing adjustment mode, and the image forming apparatus receives the information from the data source through the interface, and the latch timing adjustment mode based on the information received by the receiving means. Setting means, a storage means for storing timing information in the latch timing adjustment mode, and a latch timing adjustment mode set by the setting means, in accordance with the timing information stored in the storage means. Data receiving means for capturing predetermined data transmitted from the data source,
A determining means for determining whether or not the predetermined data is taken in normally; and a control means for setting the timing information stored in the storage means when the data is taken in by the receiving means when it is judged by the judging means to be normal. Have.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of an interface section having an image forming apparatus, an image forming system and a data latching method thereof according to the present embodiment.

In FIG. 1, 10 is a printer device 20.
A host computer, which is a data source for outputting print data, a printer device 20, and a Centronics interface cable 30.

In this configuration, the host computer 1
As shown in FIG. 2, 0 is provided with an operating system (OS), application software (AP), etc., and print data, print commands, etc. are sent to the printer device 2 via the Centronics interface.
0 is transferred, print image data is expanded from the print data, and printing based on the print image is performed.

On the other hand, the printer device 20 interprets print data and print commands sent from the host computer 10, develops them into print image data, and forms an image on recording paper as a permanent visible image. The print data mentioned here is composed of a character code, a control code, and the like. Examples of such print data include PDL (page description language) and PJL (print job language) data. The printer device 20
May be a monochrome printer or a color printer.

FIG. 2 is a functional block diagram showing the functional configuration of the host computer 10 of this embodiment.

The host computer 10 is provided with a CPU 15 for controlling the operation of the entire computer 10, a memory 16 containing an operating system, application software, device drivers, etc., and creates print data and print commands by these software, and a printer device. It is output to 20, and it is made to develop into a print image and print. A printer driver 12 suitable for the printer device 20 is provided as the device driver. The printer driver 12 includes a data latch timing adjustment flag 13 that indicates that the data latch timing is being adjusted, and a response wait maximum time register 14 that holds the maximum time to wait for the nACK signal pulse output from the printer device 20. Is equipped with. Also, Centronics Interface 11
Is an interface unit for transferring data to the printer device 20.

FIG. 3 shows a printer device 20 of this embodiment.
FIG. 3 is a block diagram showing the configuration of FIG.

In FIG. 3, the printer device 20 is a CP.
U220, ROM221 which stores the control program and various data of CPU220, RAM222 which is used as a work area of CPU220 and the like control section 22
Is controlled by 21 is Centronics. In the interface section, between the host computer 10 and the Centronics interface cable 30,
It sends and receives various signals. A command analysis unit 23 analyzes print data and print commands sent from the host computer 10. A printer engine 24 forms a permanent visible image on a recording sheet or the like based on the print image data expanded in the expansion memory 25. The expansion memory 25 stores print image data obtained by expanding the print data into a bitmap.

Reference numeral 27 is a data latch timing register for holding the timing of fetching print data from the host computer 10. Reference numeral 28 is a data latch flag for notifying the control unit 22 that the print data has been latched. 29 is a timer unit, and the control unit 22 manages the timing of outputting the Centronics interface signal based on the time counting by the timer unit 29. The bus 2a connects the above-mentioned units. The data latch timing adjustment flag 13, the response waiting maximum time register 14, the data latch timing register 27,
The data latch flag 28 may be provided in the RAM 222.

FIG. 4 is a diagram showing an example of a communication control timing adjustment command issued by the printer driver 12 of the host computer 10 of this embodiment.

This data latch timing adjustment command includes a "command number" for identifying the command.

FIG. 5 is a timing chart showing the data transfer timing using a general Centronics interface.

In FIG. 5, the DATA signal indicates print data sent from the host computer 10 to the printer device 20. This DATA signal is transmitted via an 8-bit path. The nSTROBE signal is a strobe signal output from the host computer 10 to the printer device 20, and means that print data is output to the printer device 20 when it is at a low level. BUSY
Signals are sent from the printer device 20 to the host computer 10
The high level signal indicates that the printer device 20 is busy and cannot receive new print data. The nACK signal is sent to the printer device 20.
When the response signal sent from the host computer 10 to the host computer 10 becomes low level, it means that the print data from the host computer 10 is received. The edgessns signal corresponds to the data latch flag 28 of the printer device 20 and is a signal for notifying the control unit 22 that the DATA signal from the host computer 10 has been received. Centronics interface 2 of printer device 20
When the falling edge of the nSTROBE signal is detected, 1 sets the data latch flag 28 to "1" (high level), and then sets the edgesns signal to high level and outputs it.

A more detailed description will be given based on the timing chart of FIG.

First, at time t1, the host computer 1
When 0 confirms that the BUSY signal from the printer device 20 is low level, it outputs the DATA signal (8-bit data) to be transmitted to the printer device 20. Then, at time t2, the host computer 10 moves to nSTRO
The BE signal is changed from high level to low level. As a result, the printer device 20 changes the BUSY signal from low level to high level at time t3. Next, at time t4,
The printer device 20 sets the edgesns signal to a high level and captures the DATA signal. DATA
When the signal acquisition is completed, at time t5, the printer device 20 sets the edgesns signal to the low level. Next, the host computer 10 turns on nST at time t6.
The ROBE signal is changed from low level to high level. Then, at time t7, when the nACK signal from the printer device 20 changes from the high level to the low level, the host computer 10 recognizes that the printer device 20 has received the DATA signal. Then, at time t8, the printer device 20
After changing the nACK signal from low level to high level,
At time t9, the BUSY signal is changed from the high level to the low level to notify the host computer 10 that the next DATA can be received. The above is the basic transfer sequence of the 8-bit (1 byte) DATA signal.

The time from time t2 (falling edge of nSTROBE) to time t4 (rising edge of edgessns signal) is referred to as "dltim (delay time)". This delay time “dltim” indicates the time from the fall of the nSTROBE signal until the printer device 20 internally takes in the data indicated by the DATA signal.

FIG. 6 is a waveform diagram showing an example where the Centronics interface signal is affected by electromagnetic noise.

FIG. 6 shows one of 8-bit DATA signals.
A data signal corresponding to bits is shown as a representative, and is a diagram showing a state of a signal transmitted through the Centronics interface cable 30, and actually has a disturbed waveform as shown in the diagram. In general, since the Centronics cable 30 has a structure in which a large number of conductors are bundled, noise in each signal line affects each other.

At time t1 in FIG. 6, the host computer 1
A 1-bit signal of 0 to DATA signals is output at a high level. Next, the host computer 10 sets time t2.
Changes the nSTROBE signal from high level to low level. As a result, the printer device 20 changes the BUSY signal from low level to high level at time t3. At this time, when the nSTROBE signal falls (time t2) and B
The influence of the signal change at the rise of the USY signal (time t3) is transmitted to the DATA signal, and as shown in the figure, DATA
The signal waveform is greatly disturbed. Then, when the printer device 20 fetches the 1-bit data of the DATA signal at time t4 when the level of the DATA signal is the lowest, the data signal which should originally be high level is fetched to the printer device 20 as low level. It will be.

The magnitude of the disturbance of the signal waveform and the length of the disturbance are greatly different depending on the performance and characteristics of the Centronics cable or the Centronics interface.

Therefore, in order to eliminate the influence of such noise, it is necessary to further delay the timing at which the printer device 20 takes in the data than the timing at which the strobe (nSTROBE) signal or the BUSY signal is inverted. Become.

FIG. 7 is a flow chart showing a data signal receiving process in the printing system (host computer 10 and printer device 20) of the present embodiment. Here, the host computer 10 issues a "data latch timing adjustment command" to the printer device 20, and the printer device 20 that receives the command receives DATA.
Change the timing of capturing data on the signal line.
As a result, the timing of the data latch is adjusted so that there is no influence of the above-mentioned noise (high reliability) and high-speed data transfer is possible.

Specifically, the falling edge of the nSTROBE signal output from the host computer 10 (high level →
(Low level) is detected by the printer device 20, the timing at which the printer device 20 takes in the data on the DATA signal is made longer from the shortest for each data transfer, and the data latch timing at which the printer device 20 takes in the correct data is set by the host. The latch timing is for the print data transfer between the computer 10 and the printer device 20. still,
Among these processes, the processes relating to the host computer 10 are processed according to the operating system, application programs, printer driver 12 and the like incorporated in the host computer 10, and the processes related to the printer device 20 are programs stored in the ROM 221. Is executed by the CPU 220.

In FIG. 7, first, in step S1, the printer 20 and the host computer 10 are initialized. Here, when the power of the apparatus is turned on, the printer apparatus 20 is set in a state in which it can receive the print data and the print command transferred from the host computer 10, and the process proceeds to step S2. In step S2, the host computer 10 issues the data latch timing adjustment command shown in FIG. 4 to the printer device 20 and proceeds to step S3. In step S3, the printer device 20
In step S2, the data latch timing adjustment command issued by the host computer 10 is received via the Centronics interface 21, and the command analysis unit 2
The analysis is performed in step 3, and the process proceeds to step S4. In step S4,
Between the host computer 10 and the printer device 20,
A data latch timing adjustment process (FIGS. 8 and 9) described later is performed, and the process ends.

FIG. 8 is a flowchart showing the data latch timing adjustment processing executed by the host computer 10. This flowchart is executed by the host computer 10 in the data latch timing adjustment processing in step S4 of FIG. An example of processing is shown.

To explain the outline of this processing, the host computer 10 sends the data of "0FFh (h is a hexadecimal number, the same applies below)" to the printer device 20 in the same manner as the normal print data transmission. Send with.
As a result, it waits for the nACK signal pulse, which is the response to the received data, sent from the printer device 20. This waiting time is the "HTMAX" time stored in the response waiting maximum time register 14 of FIG. If the response pulse (nACK signal) cannot be detected within the maximum waiting time, the same data “0FFh” is sent to the printer device 20 again. This operation is performed by the printer device 2
Repeat until a nACK signal sent from 0 is detected. When the nACK signal is detected, the process ends.

This operation is based on the timing chart of FIG. 5 described above.

In FIG. 8, first, in step S10, the data latch timing adjustment flag 13 of the printer driver 12 is set to "1". When the data latch timing adjustment flag 13 is set to "1", the printer driver 12 does not accept the print data transfer request from the operating system or the application program and is specified to perform the data latch timing adjustment process. . Then, the process proceeds to step S11,
The variable “htim” (set in the memory 16) indicating the time is cleared to “0”. This time variable "htim"
Is a timer variable managed by the operating system and is incremented at regular time intervals.

Next, in step S12, the timer of the operating system is started. As a result, the above-mentioned variable “htim” is incremented by 1 at regular time intervals. Then, the process proceeds to step S13, the data signal "0FFh" is sent to the printer device 20, and the process proceeds to step S13.
Proceed to 14. In step S14, the state (high level or low level) of the nACK signal of the Centronics interface 11 is checked, and the state is determined in step S15. When the ACK signal is at the low level, that is, when the response signal is received, the process proceeds to step S18, the data latch timing adjustment flag is set to "0" (data latch timing adjustment process ends), and the process ends.

On the other hand, in step S15, when the nACK signal is at high level, that is, when the response signal is not received, the process proceeds to step S16, the time variable "htim" managed by the operating system is read, and step S16 is executed.
Proceed to 17. In step S17, it is determined whether or not the value of "htim" read in step S16 is equal to or smaller than "HTMAX" set in the response waiting maximum time register 14, and if so, the process returns to step S14.

On the other hand, in step S17, the time variable "hti
If the value of “m” is greater than the maximum waiting time “HTMAX”, the response waiting maximum time has been exceeded, so the process returns to step S11, and the time variable “htim” is set to “0” again. The above process is repeatedly executed.

The value of "HTMAX" is set in advance in the response waiting maximum time register 14 of the printer driver 12.

FIG. 9 is a flowchart showing an example of the process executed by the printer device 20 in the data latch timing adjustment process in step S4 of FIG.

To explain the outline of this processing, the control unit 22 of the printer device 20 controls the interface signal of the Centronics interface 21 to receive the data from the host computer 10. Printer device 2
0 delays the timing of fetching (latching) data every time data is received (held in the data latch timing register 27 at the time indicated by the variable “dltim”) until data of “0FFh” is received. The process until the "dltim" time at the time of receiving "0FFh" data is set as the data latch timing at the time of data transfer will be described.

In FIG. 9, first, in step S20, the data latch timing adjustment flag 1 of the printer 20 is set.
Set 3 to "1". This is because when the data latch timing adjustment flag 13 is set to "1", the printer device 20 does not treat the data sent from the host computer 10 as print data but performs the data latch timing adjustment process. Use as a signal.

Next, in step S21, the data latch flag 28 is set to "0" and the process proceeds to step S22. This data latch flag corresponds to a general interrupt flag. When set to "1", the control unit 22 causes the Centronics interface data (DATA) to be transmitted.
Performs the process of capturing signal data. Next, step S2
2, the data latch timing "dltim" held in the data latch timing register 27 is set to the minimum time "DLMIN", and the process proceeds to step S23.
Here, “DLMIN” means that the printer device 20 is DATA.
It indicates the minimum value of the data latch timing for fetching the data on the signal inside, and is the value held in the RAM 222 of the control unit 22 in advance.

In step S23, the control unit 22 reads the state (high level or low level) of the nSTROBE signal of the centronics interface 21, and the process proceeds to step S24. In step S24, the nSTROB
If the E signal is at the high level, the trailing edge of the nSTROBE signal has not been detected, and the process returns to step S23. When the trailing edge of the nSTROBE signal is detected and it is determined that the nSTROBE signal is at the low level, the process proceeds to step S25. In step S25,
Centronics Interface 21 is "dlti
Data latch flag 28 after waiting for the time indicated by "m"
Is set to "1" and the process proceeds to step S26. The time management here is performed based on the time counting by the timer unit 29.

In step S26, since the data latch flag 28 is set to "1", the control section 22 takes in the data signal of the Centronics interface 21 and proceeds to step S27. In step S27, the control unit 22 sets the data latch flag 28 to "0" and proceeds to step S28 to check whether the data fetched in step S26 is "0FFh". If so, the process proceeds to step S29, the nACK signal is sent to the host computer 10, and the process proceeds to step S30. In step S30, the data latch timing adjustment flag 13
Is set to "0" and the process is terminated.

On the other hand, in step S28, the data is "0F".
If the value is other than Fh ", it means that the data cannot be normally received, and thus the process proceeds to step S31 and the control unit 2
2 is the Centronics Interface 21 nSTR
It is checked whether the state of the OBE signal (high level or low level). If the nSTROBE signal is at the low level in step S32, the rising edge of the nSTROBE signal has not been detected, and the process returns to step S31. Then, in step S32, when the rising edge of the nSTROBE signal is detected and becomes high level, the process proceeds to step S33. In step S33, the time value "dltim" is incremented by 1, and the process returns to step S23 to adjust the data latch timing again.

The delay time value "dlti" thus determined
“M” is determined as timing information for determining the latch timing of data during a normal printing operation when receiving and printing data from the host computer 10.

As described above, according to this embodiment, the timing of the data latch in the Centronics interface in the host computer 10 and the printer device 20 is adjusted and the data is taken in without requiring the operation by the operator. Timing can be optimized. As a result, highly reliable and high-speed data transfer can be performed without being affected by electromagnetic noise or the like.

[Other Embodiments] In the above embodiment, the printer device 20 latches the data on the data bus "dltim" time after detecting the falling edge of the nSTROBE signal. However, nSTROB
Since there is a transfer protocol that captures data after the rising edge of E, the data latch timing is set to nSTROB
"Dltim" at the time based on the rise of the E signal
There is also a way to determine.

FIG. 1 is a timing chart showing the data latch timing "dltim" in another embodiment.
0 is shown. As is clear from FIG. 10, nSTROBE
Time t5 after time "dltim" after the rise of the signal
The edgnesns signal rises at.

FIG. 11 is a flowchart showing a process performed by the printer device 20 in the latch timing adjustment process shown in step S4 of FIG. 7 in the other embodiment. The outline of this process will be described. The control unit 22 of the printer device 20 controls the interface signal of the Centronics interface 21 to receive the data from the host computer 10. Then, the printer device 20 receives the data of “0FFh” until the printer device 20 receives the data of “0FFh”.
Each time data is received (latched) at every data transfer (at the time indicated by the variable "dltim" and held in the data latch timing register 27), the timing is made longer, and when the data "0FFh" is received. The processing until the delay time “dltim” is set as the data latch timing at the time of data transfer is shown.

In FIG. 11, first in step S40,
The data latch timing adjustment flag 13 of the printer device 20 is set to "1". When the data latch timing adjustment flag 13 is set to "1", the printer device 20 does not treat the data transferred from the host computer 10 as print data, and the data latch timing adjustment process is performed without expanding the image data into image data. Do.

In step S41, the data latch flag 28 is set to "0" and the process proceeds to step S42. The data latch flag 28 corresponds to a general interrupt flag, and when set to "1", the control section 22 carries out a process of fetching the data signal of the Centronics interface. Next, the process proceeds to step S42, the data latch timing "dltim" held in the data latch timing register 27 is set to the minimum time "DLMIN", and the process proceeds to step S33. "DLMIN" here
Is the minimum value of the data latch timing for the printer device 20 to internally capture the data on the DATA signal, and is a value held in the RAM 222 of the control unit 22 in advance.

Next, in step S43, the controller 22 controls the nSTROBE of the Centronics interface 21.
The state of the signal (high level or low level) is read and the process proceeds to step S44. In step S44, the nST
If the ROBE signal is at the high level, the fall of the nSTROBE signal has not been detected, and the process returns to step S43. In step S44, when the nSTROBE signal is low level, the falling edge of the nSTROBE signal is detected, so the process proceeds to step S45, in which the control unit 22 controls the nSTROBE interface nST
The state (high level or low level) of the ROBE signal is read and the process proceeds to step S46.

If the nSTROBE signal is low in step S46, the rising of the nSTROBE signal has not been detected, and the process returns to step S45. Then, in step S46, when the rising edge of the nSTROBE signal is detected and it is confirmed that the nSTROBE signal has become high level, the process proceeds to step S47, and "dlt
After waiting for a time indicated by "im", the data latch flag 28 is set to "1" in the Centronics interface 21, and the process proceeds to step S48. Here, it is assumed that the time management is performed based on the time counting by the timer unit 29.

Next, in step S48, the control unit 22
Since the data latch flag 28 is set to "1", the data signal of the Centronics interface 21 is fetched and the process proceeds to step S49. Then, the control unit 22 sets the data latch flag 28 to "0" and proceeds to step S50 to check whether the data fetched in step S48 is "0FFh". If so, the process proceeds to step S51, and the host computer 10 receives the nAC
The K signal is output and the process proceeds to step S52. Step S5
In 2, the data latch timing adjustment flag 26 is set to "0" and the process is ended.

In step S50, the data is "0F".
If the value is other than Fh ", data is not normally received, so the flow advances to step S53 to set the delay time" dltim "to 1
Only, and the process returns to step S43.

The present invention may be applied to a system composed of a plurality of devices such as a host computer, an interface and a printer, or to an apparatus composed of a single device such as a copying machine. Further, it goes without saying that the present invention can be applied to the case where it is implemented by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium to the system or device, the system or device operates in a predetermined manner.

As described above, according to this embodiment, when the data latch timing adjustment mode is set in the printer device connected by the Centronics interface, the data latch timing is received each time data is transferred from the host computer. , The data can be accurately received without the influence of noise, and the optimum data latch timing that does not reduce the data transfer rate can be obtained.

Then, thereafter, by latching the received data at the set data latch timing, the data signal of the Centronics interface is taken in at the optimized timing, and it is highly reliable without being affected by noise. In addition, there is an effect that high-speed data transfer can be performed.

[0066]

As described above, according to the present invention, by changing the delay time from the switching timing of other signals according to the interface used,
There is an effect that a data signal can be transmitted and received without being affected by noise.

Further, according to the present invention, it is possible to prevent the data transfer time from increasing and to transmit the data signal to form an image.

Further, according to the present invention, there is an effect that the optimum data fetching timing can be automatically determined between the data source and the image forming apparatus to transmit / receive data.

[0069]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an image forming system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a functional configuration example of a host computer according to the present embodiment.

FIG. 3 is a block diagram showing a configuration example of a printer device according to the present embodiment.

FIG. 4 is a diagram showing an example of a data latch timing adjustment command in the present embodiment.

FIG. 5 is a timing chart showing data transfer timing in a general Centronics interface.

FIG. 6 is a waveform diagram showing how a DATA signal is affected by electromagnetic noise.

FIG. 7 is a flowchart showing an example of a processing procedure in the image forming system of the present embodiment.

8 is a flowchart showing an example of processing executed by a host computer in the data latch timing adjustment processing of FIG. 7. FIG.

9 is a flowchart showing an example of processing executed by the printer device in the data latch timing adjustment processing of FIG. 7.

FIG. 10 is a timing chart showing data transfer timing of a Centronics interface according to another embodiment of the present invention.

FIG. 11 is a flowchart showing an example of processing executed by a printer device in a data latch timing adjustment processing according to another embodiment of the present invention.

[Explanation of symbols]

 10 host computer 11,21 Centronics interface 12 printer driver 13 data latch timing adjustment flag 14 response waiting maximum time register 20 printer device 22 control unit 23 command analysis unit 24 printer engine 25 expansion memory 27 data latch timing register 28 data latch flag 29 Timer unit 220 CPU 221 ROM 222 RAM

Claims (18)

[Claims] 1. An image forming apparatus connected to a data source via an interface, comprising: receiving means for receiving information from the data source via the interface; and based on the information received by the receiving means. Setting means for setting the latch timing adjustment mode, storage means for storing timing information in the latch timing adjustment mode, and timing information stored in the storage means when the latch timing adjustment mode is set by the setting means The data receiving means for taking in the predetermined data transmitted from the data source according to the above, the judging means for judging whether the taking of the predetermined data is normal, and the storage means when the judging means judges that the data is normal. The timing information stored in the receiving means is used as data acquisition timing. An image forming apparatus comprising: 2. The method according to claim 1, further comprising a changing unit for changing the timing information stored in the storage unit when the determining unit determines that the predetermined data is not normally captured. 1. The image forming apparatus according to 1. 3. The image according to claim 1, wherein the timing information defines a delay time from the output timing of the information output from the data source to the fetching of data in the data receiving means. Forming equipment. 4. The image forming apparatus according to claim 1, wherein the interface is a Centronics interface. 5. The timing information defines a delay time from a time when a strobe signal of a data signal output from the data source becomes valid to a time when data is taken in by the data receiving means. The image forming apparatus according to item 4. 6. The timing information defines a delay time from the time when the strobe signal of the data signal output from the data source becomes valid to the time when it is taken in by the data receiving means. The image forming apparatus according to claim 4. 7. An image forming system having a data source and an image forming apparatus that receives information from the data source and forms an image, the data source transmitting information to the image forming apparatus via an interface. The image forming apparatus includes means for transmitting and setting a latch timing adjustment mode, the image forming apparatus receiving means for receiving information from the data source via the interface, and latching means based on the information received by the receiving means. Setting means for setting the timing adjustment mode, storage means for storing timing information in the latch timing adjustment mode, and when the latch timing adjustment mode is set by the setting means, the timing information stored in the storage means Data receiving means for receiving the predetermined data transmitted from the data source according to A judgment means for judging whether or not the predetermined data is taken in normally, and a control means for setting the timing information stored in the storage means when the judgment means is normal as the data taking-in timing in the receiving means, An image forming system comprising: 8. The method according to claim 1, further comprising changing means for changing the timing information stored in the storage means when the judging means judges that the predetermined data is not normally taken in. Item 7. The image forming system according to Item 7. 9. The image according to claim 7, wherein the timing information defines a delay time from the output timing of the information output from the data source to the capture of data in the data receiving means. Forming system. 10. The interface of claim 7, wherein the interface is a Centronics interface.
10. The image forming system according to any one of items 1 to 9. 11. The timing information defines a delay time from a time when a strobe signal of a data signal output from the data source becomes valid to a time when data is taken in by the data receiving means. 10
The image forming system according to 1. 12. The timing information defines a delay time from a time when a strobe signal of a data signal output from the data source is invalid to a time when data is taken in by the data receiving means. The image forming system according to claim 10. 13. Data transfer in an image forming system having a data source and an image forming apparatus that receives information from the data source to form an image, wherein the image forming apparatus is from the data source via an interface. Transmitting information to the latch timing adjustment mode, receiving information from the data source via the interface, setting the latch timing adjustment mode based on the received information, When the latch timing adjustment mode is set, the step of fetching the predetermined data transmitted from the data source according to the timing information, the step of determining whether the fetch of the predetermined data is normal, and the fetching of the predetermined data The timing information when it is judged that the A data transfer method comprising: a step of setting only timing. 14. The data transfer method according to claim 13, further comprising the step of changing the timing information when it is determined that the predetermined data has not been normally captured. 15. The data according to claim 13, wherein the timing information defines a delay time from the output timing of the information output from the data source to the capture of the data in the image forming apparatus. Transfer method. 16. The interface of claim 1, wherein the interface is a Centronics interface.
16. The data transfer method according to any one of 3 to 15. 17. The timing information defines a delay time from a time when a strobe signal of a data signal output from the data source becomes valid to a time when data is taken in the image forming apparatus. 16. The data transfer method described in 16. 18. The timing information defines a delay time from a time when a strobe signal of a data signal output from the data source is invalid to a time when data is taken in the image forming apparatus. The data transfer method according to claim 16.