JP2003258804A - Controller and controlling method for inter-device data communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit only untransmitted remaining data after reconstructing network topology if a communication network configuration changes during data transmission in data communication between devices. <P>SOLUTION: In communication between a host and a printer, for example, with IEEE 1394, the printer counts and stores the number of pieces of received data and the number of pieces of remaining data while receiving print data from the host (S43). If a network configuration changes by the extraction and addition of a cable or the like in the middle of receiving the print data, a bus is reset (S45), network topology is reconstructed (S46 and S47), and just after that, the host sends to the printer a receiving request for print data that is the same as print data which is being transmitted just after the bus resetting (S48). The printer skips the number of pieces of received data stored just before the bus resetting from the head in print data requested for reception and receives only subsequent remaining data (S51). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus and method for controlling data communication between devices, such as communication of print data and control data between a host device and an electronic printer.

[0002]

2. Description of the Related Art Many types of communication interfaces between devices are known. Some types of communication interfaces, such as IEEE 1394, have taken some measures to ensure that data can be transmitted even if an accident occurs.

For example, suppose that a device on the receiving side is unable to proceed with data reception for some reason while data is being transmitted from one device to the other device via the IEEE1394 communication interface. In this case, by transmitting a response indicating that the processing is not completed from the receiving side device to the transmitting side device, the data communication can be temporarily interrupted and the same data can be transmitted again later.

Also, during the transmission of data from one device to the other, the configuration of the IEEE 1394 communication network to which both devices are connected changes (for example, communication is performed at some point of the communication network). (The cable is unplugged, the communication cable is reconnected, etc.)
And In this case, immediately after the configuration of the communication network is changed, the bus reset is performed by both devices to reconstruct the network topology, and immediately after that, the same data as that transmitted immediately before the bus reset is transmitted again. It is like this.

[0005]

As an illustrative example, consider data communication between a host device and an electronic printer. The types of data sent from the host device to the printer include print data for causing the printer to print a document and certain special operations (for example, returning printer status, ink cartridge replacement, test printing, head cleaning). Etc.) for controlling the printer. In the host device, an application program that outputs print data (for example, printer driver) or an application program that outputs control data (for example, printer utility)
Respectively, after outputting the data to the printer,
The printer waits for a response from the printer indicating the reception status or processing status of the data and counts the waiting time. If a predetermined time limit elapses without a response (timeout event occurs), the application program cannot communicate with the printer (for example, the printer is not connected or the power is not turned on). Therefore, a predetermined coping method will be taken.

By the way, even when communication between the printer and the host device is possible, the above-mentioned timeout event may occur.

For example, after the printer starts receiving the print data, if it takes too long to completely receive all the print data, and if the reply to the host device is delayed for a long time, the above-mentioned timeout event occurs. Will occur.

Further, when a communication interface having different logical channels such as a data channel and a control channel is used like IEEE1394,
A timeout event may occur due to the following problems. That is, many systems are designed to send print data on the data channel and control data on the control channel. In this case, according to the standard of the communication interface, it should be possible to send the print data and the control data at the same time by using the data channel and the control channel in parallel.
In some real-life personal computer systems,
When print data and control data are sent simultaneously in parallel using these two channels, a problem may occur in which a response from the printer regarding the control data is not normally recognized by the application program in the host device. The cause has not been clarified yet, but anyway, when such trouble occurs, the above-mentioned timeout event occurs with respect to the control data.

As described above, in a system in which a time-out event occurs in the application program of the host device, even if the communication interface itself is capable of compensating for interruption of data communication as in the above IEEE 1394, the host No reliable data communication can be guaranteed between the device and the printer.

Further, as described above, in the IEEE1394 communication network, if the network configuration changes during the transmission of print data, a bus reset is performed to reconstruct the network topology, and then immediately before the bus reset. The same print data as is retransmitted. In this case, in the printer, regarding the part of the print data that has been received before the bus reset,
It is desirable to selectively receive only the remaining portion that has not been received yet without receiving it again. However, it is not easy to selectively receive the remaining data. That is, since the network topology is reconstructed by the bus reset, the addresses of the host device and the printer on the network, the addresses of the resources in the host device, etc. will be different from those before the bus reset. There is. Then, the printer cannot know which part of the print data in the host device has been received and which part has not been received.

The above-mentioned problems may exist not only in communication between the host device and the printer but also in communication between various other devices.

The present invention has been made in view of the above circumstances, and an object thereof is to solve the latter problem of the two problems of timeout and network topology reconstruction.

That is, an object of the present invention is that in data communication between devices, if the communication network configuration changes during data transmission, only the untransmitted remaining data can be selectively transmitted after the network topology is reconstructed. To do so.

[0014]

According to a first aspect of the present invention, there is provided a device for controlling data communication between devices on a communication network, the device having a predetermined data size from the device at the transmitting side at a receiving side device. Data receiving means for gradually receiving data, and received data size storing means for updating and storing the received data size or the unreceived remaining data size in the receiving device as the reception of the data progresses. Immediately after the configuration of the communication network changes,
Topology reconstructing means for reconstructing the topology of the communication network by performing bus reset in the receiving side device and the transmitting side device, and a data reception request immediately after the reconstruction of the topology in the transmitting side device. Means for sending again to the receiving side device, and immediately after the reconstruction of the topology, the receiving side device receives the data reception request from the transmitting side device, and the data requested by the reception request is immediately before the bus reset. In the receiving side device, a determining means for determining whether or not the received data is the same as the received data,
As a result of the determination, if the requested data is the same data received immediately before the bus reset, the requested data size or the remaining data size stored immediately before the bus reset is used. A data re-receiving unit that skips a data portion corresponding to the received data size from the beginning of the data and selectively receives a subsequent unreceived data portion.

In a preferred embodiment of the control apparatus of the present invention, the transmission side apparatus includes means for giving a signature for distinguishing each data transmitted to the reception side apparatus from other data. Further, the means further comprises: if the data requested by the reception request immediately after the reconstruction of the topology is the same data as the data immediately before the bus reset, the bus reset is performed for the requested data. Assign the same signature as the previous data. Then, the determination means of the receiving device compares the signature of the data received immediately before the bus reset with the signature of the requested data, so that the requested data is received immediately before the bus reset. It is designed to judge whether it is the same as the data.

Also, in a preferred embodiment, if the requested data is different from the data received immediately before the bus reset in the receiving side device as a result of the determination, the requested device is requested. It further comprises means for progressively receiving all of the data.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION As an example for explanation,
It deals with data communication between a host device such as a personal computer and an electronic printer such as a laser printer or an inkjet printer.

FIG. 1 shows an embodiment of the present invention applied to data communication between a host device and an electronic printer.
1 shows a configuration of a program or a hardware module in a host device related to data communication.

The printer driver 10 creates and outputs print data of a document desired by a user in response to a request from the user. The print data output from the printer driver 10 is temporarily stored in the spooler 30, and then sent out from the spooler 30 to be sent to the port monitor 40, the IEEE 13
94.3 Controller 50, SBP2 Controller 60, IEEE13
94 bus driver 70, IEEE1394 connector 80 and IEEE13
94 It is designed to be sent to the printer through a cable 90.

Further, the printer utility 20 obtains the current status of the printer from the printer periodically or in response to the user's request, and in response to the user's request, the printer utility 20 performs various maintenance operations on the printer. It outputs control data for performing special operations (for example, ink cartridge replacement, head cleaning, test printing, status printing, paper feed / paper discharge, etc.). The control data output from the printer utility 20 is sent to the printer through the port monitor 40, the IEEE1394.3 controller 50, the SBP2 controller 60, the IEEE1394 bus driver 70, the IEEE1394 connector 80, and the IEEE1394 cable 90.

The IEEE 1394.3 controller 50 is a standard IEEE
The communication protocol control conforming to 1394.3 is performed, and the communication control operation of the host device according to the principle of the present invention described below is mainly performed by the IEEE 1394.3 controller 50. SBP2 controller 60 is a standard
It controls the communication protocol based on SBP2.
The IEEE1394 bus driver 70 performs particularly physical communication signal control conforming to the standard IEEE1394. IEEE1394
The connector 80 is a physical connector to which the IEEE1394 cable 90 is connected.

Although not shown, the printer side also has a port monitor, an IEEE1394.3 controller, an SBP2 controller, an IEEE1394 bus driver, and an IEEE1394 connector as described above. A program or circuit for interpreting print data or control data from the host device and controlling the printer exists above the port monitor. The communication control operation of the printer according to the principles of the present invention described below is mainly performed by the IEEE 1394.3 controller in the printer.

FIG. 2 shows a schematic procedure of data communication between a host device and a printer conforming to IEEE1394.

In the host device, the printer driver 1
0 or a request for transmission of print data or control data from the printer utility 20 occurs, as shown in FIG.
A data block 100 called a request block (hereinafter referred to as "ORB") and a data buffer 110 storing print data or control data to be transmitted are constructed, and an ORB read request is sent to the printer as shown in step S1. Send to. The printer is from the host device
In response to the ORB read request, as shown in step S2,
Read the ORB from the host device.

In the ORB, the operation requested by the printer from the host device (for example, reading or writing of data)
Also, the start address and data size of the data buffer 110 are described. The printer is step S
3. Perform the action requested by the ORB, as shown in 3. A typical example of an operation required by the ORB is reading print data or control data from the data buffer 110 (that is, sending print data or control data from the host device to the printer). The operation required by another kind of ORB is, for example, to write specific data in the printer (for example, status data indicating the current state of the printer) to the data buffer 110 in the host device. is there. In any case, after executing the operation requested by the ORB, the printer sends a data block called a status block (hereinafter referred to as “SB”) indicating the execution result in the host device, as shown in step S4. To the register 120 on the memory. The SB contains the address of the corresponding ORB and the completion status of the operation requested by that ORB (for example, completed or incomplete).
Etc. are described. The SB is, in short, a response from the printer to a processing request (ORB) from the host device.

FIG. 3 shows the structure of the ORB.

As shown in FIG. 3, the ORB 100 contains fields such as pointer, data buffer address, operation, data buffer size, queue number, signature, and so on.

Here, the pointer field in the ORB 100 describes the pointer to the subsequent ORB 100-2 when another ORB 100-2 is linked to this ORB 100. 3 shows an example in which one ORB100-2 is linked to another ORB100-2, but another ORB is linked after the second ORB,
The ORB chain can be extended. When multiple ORBs are serially linked in this way, the printer reads the previous ORB, performs the requested processing, returns SB to the host device, and then continues to the next ORB.
To perform the required processing. For example, when the printer utility 20 monitors the status of the printer, an ORB requesting the printer to read control data for preparing the printer for the status data from the host device, and the prepared status data to the host device. Will be linked with the ORB that requests the printer to write to.
In this case, the printer receives the first ORB, reads the control data, prepares the status data according to the control data, then receives the second ORB and outputs the status data.
Return the data to the host device.

The head address of the data buffer 110 in the host device is described in the data buffer address field in the ORB 100. The operation field describes the type of operation required of the printer, for example, reading print data or control data from the data buffer 110, or writing status data to the data buffer 110. It The data size of the data buffer 110 is described in the data buffer size field.

A queue number field in the ORB 100 describes a queue number indicating a logical channel used when the operation requested by the ORB 100 is executed.
The IEEE 1394 communication interface has two logical channels, a data channel and a control channel. Therefore, in the queue number field, the queue number indicating either the data channel or the control channel is described. For example, a queue number indicating a data channel is written in the ORB that requests reading of print data. Therefore, the print data is transmitted from the host device to the printer using the data channel. Further, for example, the queue number indicating the control channel is written in the ORB requesting the reading of the control data. Therefore, the control data is transmitted from the host device to the printer using the control channel. Also, for example, the queue number indicating the control channel is written in the ORB requesting the writing of the status data. Therefore, the status data is transmitted from the printer to the host device using the control channel.

The signature field in the ORB 100 describes a signature which is an identification number for distinguishing this ORB 100 from other ORBs. The printer compares the signature of the ORB it just received with the signature of the ORB it received earlier, so that if the two signatures are different, the ORB just received is a new ORB different from the previous ORB. On the other hand, if both signatures match, the ORB received now can be recognized as the same ORB as the previous ORB retransmitted from the host device.

FIG. 4 shows the structure of the SB.

As shown in FIG. 4, the SB 200 has fields such as an ORB address, a completion status / error status, and an unprocessed data size.

In the ORB address field in SB200, the address of the ORB corresponding to this SB200 in the host device is described. The host device receives the SB200
It is possible to identify which ORB the SB 200 responds to by the ORB address in the.

The completion status / error status field in the SB 200 describes whether the requested operation of the corresponding ORB has been completed or not completed, and if the operation is not completed, the cause is an error or a timeout (described later). It

The size of the unprocessed data in the SB 200 is the size of the unprocessed data remaining in the data buffer 110 (or of the already processed data when the requested operation of the corresponding ORB is uncompleted). Size) is described.

FIG. 5 shows a specific example of a procedure for transmitting print data and control data from a host device to a printer under communication control according to the principles of the present invention.

As shown in FIG. 5, first, in the host device, in step S11, the printer driver issues a print data transmission request (that is, print data is output).
And Then, in step S12, the ORB (hereinafter abbreviated as "D_Ch_ORB") of the data channel requesting the printer to read the print data through the data channel (hereinafter abbreviated as "D_Ch") and the data storing the print data. A buffer is built in the host device. Further, the printer driver starts time counting in step 13 after issuing the print data transmission request.

In step 14, the printer reads the D_Ch_ORB from the host device. (Note that depending on the printer
Before reading the ORB, the ORB read request is sent from the host device to the printer as described above, but the description of this step will be omitted below. ) Subsequently, in step S15, the printer starts the operation requested by the D_Ch_ORB, that is, the operation of reading the print data from the data buffer in the host device. The size of the print data is usually quite large, and the print data is divided into a large number of data blocks (packets), which are sequentially read by the printer from the first data block to the last data block (that is, data block unit). Is transmitted from the host device to the printer). Immediately after starting reading the print data, the printer starts time counting in step S16.

While the print data is being transmitted from the host device to the printer, the printer utility of the host device issues a control data transmission request (that is, the control data is output in step S17). ). In fact, the printer utility regularly tries to get status data from the printer, so
Control data for status acquisition is frequently issued during transmission of print data. When a control data transmission request is issued, the ORB of the control channel (hereinafter, "C_C_C" that requests the printer to read the control data through the control channel (hereinafter, "C_Ch")).
abbreviated as “h_ORB”) and a data buffer storing the control data thereof are built in the host device. However, at that time, if print data is being sent through D_Ch,
The host device (according to the IEEE 1394 standard, D_Ch and C_Ch
Print data and control data can be sent simultaneously and in parallel, but without intentionally doing so) Step S1
As shown in 8, the control data transmission request associated with that C_Ch_ORB is put in the C_Ch transmission suspension queue, thereby temporarily suspending the transmission of control data. After issuing the control data transmission request, the printer utility starts time counting as shown in step S19.

Now, each of the printer driver and the printer utility in the host device has the steps described above.
After starting each time count in S13 and S19,
When a timeout event occurs, in which the count value reaches a predetermined time limit (for example, 30 seconds) without receiving a response from the printer, communication with the printer is disabled (for example, the printer is connected to the host device). If it is not or the power is not turned on), the prescribed countermeasures will be taken.

In order to prevent such a time-out event from occurring in the host device, the printer operates as follows. That is, the printer uses the above-described step S15.
After starting to read the print data with, before the reading of all the print data is not finished yet, as shown in step S20, some error (for example,
If it becomes impossible to read further print data due to a paper out error etc.), immediately return the SB indicating that the request processing is not completed to the host device, as shown in step S21. To do. Further, even if no error occurs, if a timeout event occurs that the count value of the time count started in step S16 reaches a predetermined upper limit time before the reading of all print data is completed (step S20) Moreover, the printer immediately returns the SB indicating that the request processing has not been completed to the host device (step S21). Here, the upper limit time at which the time-out event occurs in the printer is set to be sufficiently shorter than the time limit during which the time-out event occurs in the host device. For example, when the time limit for timeout on the host side is, for example, 30 seconds, the upper limit time for timeout on the printer side is, for example, 5 seconds. Even if the above error occurs, the SB
Instead of sending back, the time count is started from the time when the error occurs, and when the count value reaches the upper limit time (that is, a time sufficiently shorter than the timeout limit time on the host side, for example, 5 seconds), The completed SB may be returned.

When the unfinished SB is returned to the host device in step S21, the host device returns to step S22.
As shown in, the printer driver is notified that the printer has received an incomplete response. That is, the printer driver receives a response from the printer. At this point, as is clear from the explanation that the upper limit time is short,
Since the time count value of the printer driver has not reached the above time limit, the printer driver does not generate a time-out event. At the same time as the reception of the incomplete SB, as shown in step S23, D_Ch_O requesting the reading of the print data that has been performed up to now is performed.
The print data transmission request associated with the RB is put into the D_Ch transmission hold key, which temporarily suspends the print data transmission that has been performed up to now. At the same time, as shown in step S24, the control data transmission request that has been waiting in the C_Ch transmission suspension queue until now is taken out from the transmission suspension queue and executed. As a result, C_Ch_ORB is read by the printer (step S25), and then C_Ch_ORB is read.
The printer reads the control data requested by the ORB (step S26). Since the data size of control data is usually much smaller than that of print data (for example, it fits in one or a few data blocks or packets), reading control data is completely different from the above timeout time limit. It will be completed in a very short time so as not to be. Further, even if an error occurs in the printer, in most cases, the printer can read the control data, and thus the reading of the control data is instantly completed. When the reading of the control data is completed, the printer returns SB indicating that the reading of the control data is completed to the host device, as shown in step S27.

In the host device, when the control data read completion SB is returned from the printer, the printer utility is notified that there is a response from the printer, as shown in step S28. That is, the printer utility receives a response from the printer. At this point, as is clear from the above description, the time count value of the printer utility has not reached the time limit, so that the printer utility does not generate a time-out event. Simultaneously with the reception of the completed SB, as shown in step S29, the print data transmission request in the D_Ch transmission suspension queue is taken out from the transmission suspension queue and executed. As a result, the same D_Ch_ORB as the previous D_Ch_ORB is read into the printer again (step S3
0), and then the printer reads the print data requested by the D_Ch_ORB (step
S31). At this time, the printer remembers the size of the data that has already been read and the size of the remaining data that has not been read at the time of the previous print data read, and uses it to read the already read data from the data buffer. Skip and read only the remaining data that has not been read yet. (Although not shown, when reading this data, the time count is performed in the same manner as in step S16 described above.) When the reading of all the print data is completed, the printer displays the print data as shown in step S32. The SB indicating that the reading is completed is returned to the host device. In the host device, the printer driver is notified that the printer has responded that the print data has been read.

When the printer reads the print data smoothly without any problem, the print data reading is completed in a time much shorter than the time-out limit described above. The printer utility never triggers a timeout event.

FIG. 6 is a specific example of the procedure of data communication before and after bus reset when the configuration of the IEEE 1934 communication network in which the host device and the printer are connected is changed under the communication control according to the principle of the present invention. Show.

As shown in FIG. 6, the printer has a step
When a certain ORB (which may be D_Ch or C_Ch, but is D_Ch_ORB in this example) is read from the host device in S41, the ORB is immediately stored in step S42 (in this stored content,
Of course, the ORB's signature is also included). Then, in step S43, the printer executes the data read from the requested host device by the ORB. While reading data, the printer counts and stores the number of processed (read) data (or data size) and the number of unprocessed (not read) remaining data (or data size). To do.

Here, while the printer is reading data, the IE connected to the host device and the printer
EE1934 It is assumed that the configuration of the communication network has changed (for example, the communication cable is unplugged somewhere in the communication network, or the communication cable is plugged in again). Then, immediately after the network configuration changed,
A bus reset event occurs in the host device and the printer in step S45, and the IEEE1934 communication network topology is reconstructed in the host device and the printer as shown in steps S46 and S47. Immediately after the reconstruction of the network topology, as shown in step S48, the ORB having the same contents as the ORB transmitted immediately before the bus reset is sent again from the host device to the printer. The printer reads the ORB in step S48, and in step S49, the signature of the current ORB and step S42.
Compare with the previous ORB signature before bus reset stored in. As a result, if the signatures match, the printer recognizes that this ORB is the same as the previous ORB. Then, in step S50, the printer checks whether the number of remaining data stored in step S43 is zero (or the number of processed data stored in the previous time and the number of processed data stored in this time).
You may check the number of remaining data by calculating it from the data size described in the ORB). If the number of remaining data is not zero, the printer recognizes that the reading of the data requested by the previous ORB has not been completed, and in step S51, the start address of the data buffer specified by the ORB. Skip the number of processed (read) data from and read only the remaining data that has not been read yet. In this way, the printer manages the position in the data buffer where the data reading is interrupted, using the number of data (data size), not the address on the data buffer. Therefore, even if the network topology is changed by the bus reset, the remaining data can be accurately found in the data buffer and selectively read. When the reading of all the requested data is completed, the printer returns the completed SB to the host device in step S52.

7 to 13 show detailed procedures of communication control between the host device and the printer for realizing the above-described specific operation.

FIG. 7 shows a control flow of the host device when a data transmission request such as print data and control data is generated.

As shown in FIG. 7, when a data transmission request is generated, first, whether it is a data transmission request to D_Ch (for example, print data transmission request), or a data transmission request to C_Ch (for example, control data). (S61, S62). As a result, if it is a data transmission request to D_Ch, D_Ch_ORB for requesting the printer to read the data is constructed (S63), and the D_Ch_OR
The data transmission request associated with B is put in the D_Ch transmission hold queue (S64). If it is a data transmission request to C_Ch, C_Ch_ORB for requesting the printer to read the data is constructed (S65), and the C_Ch_ORB
The data transmission request associated with is put into the C_Ch transmission hold queue (S66).

FIG. 8 shows the control procedure of the host device when transmitting the ORB.

As shown in FIG. 8, first, in order to know whether or not another ORB process is currently being executed,
The ORB processing flag is checked (S71). As a result, OR
If the B processing flag is ON, the ORB is not transmitted because the processing of another ORB is currently being executed. On the other hand, if the ORB processing flag is OFF, no other ORB processing is currently being executed, so first, it is checked whether or not there is a data transmission request in the C_Ch transmission suspension queue (S72). .

As a result, if there is a data transmission request in the C_Ch transmission suspension queue, the transmission request is extracted from the C_Ch transmission suspension queue (S73). Then, the C_Ch_ORB incomplete flag is checked (S74). As a result, if the C_Ch_ORB incompletion flag is ON, it means that the data transmission request fetched from the C_Ch transmission hold queue has been executed in the past but was interrupted because it was incomplete. The signature of C_Ch_ORB associated with the data transmission request that has been
If the Ch_ORB incompletion flag is OFF, it means that the data transmission request fetched from the C_Ch transmission hold queue is a new data transmission request, so the signature of C_Ch_ORB associated with the fetched data transmission request is set Update (S76). Then, the C_Ch_ORB is transmitted to the printer (S76) (that is, a read request for the C_Ch_ORB is transmitted to the printer, and the printer is made to read the C_Ch_ORB). Then, the ORB processing flag is turned ON (S
77).

In this way, the host device preferentially executes the data transmission request if it exists in the C_Ch transmission suspension queue, and if there is no request in the C_Ch transmission suspension queue, then Then, the data transmission request in the D_Ch transmission hold queue is checked (S78).

As a result, if there is a data transmission request in the D_Ch transmission suspension queue, the transmission request is extracted from the D_Ch transmission suspension queue (S79). Then, the D_Ch_ORB incomplete flag is checked (S80). As a result, if the D_Ch_ORB incompletion flag is ON, it means that the data transmission request fetched from the D_Ch transmission hold queue has been executed in the past but was interrupted because it was incomplete. The signature of D_Ch_ORB associated with the data transmission request remains unchanged from the previous time, but
If the Ch_ORB incompletion flag is OFF, it means that the data transmission request fetched from the D_Ch transmission pending queue is a new data transmission request, so the D_Ch_ORB signature associated with the fetched data transmission request is set. Update (S81). Then, the D_Ch_ORB is sent to the printer (S82) (that is, a read request for the D_Ch_ORB is sent to the printer to cause the pudding to read the D_Ch_ORB). Then, the ORB processing flag is turned ON (S
83).

If there is no request in either the C_Ch transmission suspension queue or the D_Ch transmission suspension queue, the ORB processing flag is turned off (S84).

FIG. 9 shows the control procedure of the host device immediately after the bus reset.

As shown in FIG. 9, immediately after the bus reset, the host device transmits the ORB transmitted immediately before the bus reset,
The same signature is sent to the printer again (S91). Then, the ORB processing flag is turned on (S92).

FIG. 10 shows a control procedure of the printer when the printer receives the ORB (that is, reads the ORB from the host device).

As shown in FIG. 10, upon receiving the ORB, the printer stores and saves the ORB (S101). The signature contained in this stored ORB will be used to determine the same / non-identity of this ORB and the ORB received previously or next time, as described above. continue,
The printer determines whether the received ORB belongs to D_Ch or C_Ch (S102, S103). If the result is D_Ch_ORB, then it is checked if the printer is currently in an error or normal state. As a result, if there is an error condition, OR
An SB indicating that the processing requested by B is incomplete due to an error is returned to the host device (S105).

On the other hand, if the result of the check in step S104 is that the printer is in a normal state, the timer for counting up to the above-mentioned upper limit time (for example, 5 seconds) is started (S105),
The ORB signature received this time and the O received last time
The signature of RB is compared (S107). As a result, if the two signatures match, this means that the current ORB is a retransmitted previous ORB. In that case, the printer next checks whether or not the number of remaining data stored at the time of the previous ORB processing execution is zero (S10).
7). (Note that instead of using the number of remaining data that was stored when the previous ORB was executed, the number of processed (read) data that was stored when the previous ORB was executed and the number specified by the current ORB were specified. The number of remaining data may be calculated from the data buffer size that was saved.) As a result, if the number of remaining data is not zero, it means that the previous ORB request processing was incomplete. The printer is
From the start address of the data buffer specified by the ORB,
The address is skipped by the number of processed data (the number of read data) stored in the previous ORB, and the unprocessed remaining data (for example, the remaining print data) starts to be read from the next address ( S110). And
The D_Ch_ORB processing flag is turned ON (S111).

On the other hand, if the number of remaining data is zero as a result of the check in step S109, it means that the request processing of the previous ORB has already been completed, and therefore the printer outputs an SB indicating that the request processing has been completed. To the host device (S11
2).

If the result of the signature comparison in step S107 described above is that the previous and current signatures are different, this means that this ORB is a new ORB different from the previous one, so the printer Data (for example, print data) from the start address of the data buffer specified by
Starts reading (S108). Then, the D_Ch_ORB processing flag is turned ON (S111).

Further, the OR received in the above step S103
If B was for C_Ch, then the printer
Reading of data (for example, control data) is started from the start address of the data buffer designated by h_ORB (S113). Then, the C_Ch_ORB processing flag is turned ON (S114).

Now, step S108 of FIG. 10 described above or
In the process of reading data (for example, print data) by D_Ch started in S11, the data is divided into a large number of data blocks (or packets) as described above, and the printer determines that a large number of data blocks. Are sequentially read one block at a time.

FIG. 11 shows a control procedure performed by the printer each time reading of one data block by D_Ch is completed.

As shown in FIG. 11, when the reading of one data block is completed, the printer increases the number of processed data (the number of read data) by one data block and decreases the remaining data number by one data block ( S12
1). Then, from the updated number of processed data or the number of remaining data, the printer checks whether or not reading of all data blocks specified in the ORB is completed (S122). As a result, if the reading of all the data blocks is not completed yet, the reading of the next data block is started (S123). On the other hand, when all the data blocks have been read, the completed SB is returned to the host device (S1
24), and the D_Ch_ORB processing flag is turned off (S12
Five).

Referring again to FIG. 10, the printer uses D_Ch
When the data reading is started in step S106, a timer is started in step S106 to count the time required for reading. Then, as already explained, if the count value of the timer reaches a predetermined upper limit time (for example, 5 seconds) before the reading of all the data requested by the ORB is completed, a timeout event occurs. Become.

FIG. 12 shows the control procedure of the printer when a timeout-out event occurs during data reception by D_Ch.

As shown in FIG. 12, when a time-out event occurs (Yes in S131), the printer uses D_Ch_ORB.
The processing flag is checked (S132). As a result, D_Ch
If the _ORB processing flag is ON, it means that the reading of all the data requested by D_Ch_ORB has not been completed yet, so the printer hosts the SB that the requested processing has not completed due to timeout. Return to device (S1
33) Then, the D_Ch_ORB processing flag is turned off, and the data reading at that D_Ch is temporarily interrupted (S13).
Four).

FIG. 13 shows the control procedure of the host device when the SB is received from the printer.

As shown in FIG. 13, when the SB is received from the printer, the host device interprets the received SB,
It is checked whether the processing requested by the ORB has been completed normally (S141). As a result, if completed, the resource related to the completed ORB is released (S142). If the completed ORB belongs to D_Ch (D in S143,
_Ch), the D_Ch_ORB incompletion flag is turned off (S144), and if the completed ORB is C_Ch (C_C in S143).
h), C_Ch_ORB incomplete flag is turned off (S145). Then, the communication control of the host device proceeds to the processing for ORB transmission shown in FIG.

As a result of the completion check in step S141,
If the ORB request processing is incomplete, the host device determines that the incomplete ORB is of D_Ch (D_C in S146).
h), put the request associated with the uncompleted ORB in the D_Ch transmission hold queue (S147), and set the D_Ch_ORB incomplete flag to ON
(S148). On the other hand, if the uncompleted ORB belongs to C_Ch (C_Ch in S146), the request associated with the uncompleted ORB is placed in the C_Ch transmission hold queue (S149), and C_Ch
Turns on the _ORB incomplete flag (S150). Then, the communication control of the host device proceeds to the processing for ORB transmission shown in FIG.

Although the embodiment of the present invention has been described above, this is merely an example for explaining the present invention, and the scope of the present invention is not limited to this embodiment. Therefore, the present invention can be implemented in various other modes without departing from the gist thereof. For example, the present invention is applicable not only to data communication between the host device and the electronic printer, but also to data communication between various other devices. Also,
The present invention is applicable not only to data communication by IEEE1394, but also to data communication using various other communication interfaces.

[Brief description of drawings]

FIG. 1 shows a configuration of a program or a hardware module in a host device related to data communication in an embodiment of the present invention applied to data communication between a host device and an electronic printer.

FIG. 2 is a diagram showing a schematic procedure of data communication between a host device and a printer in conformity with IEEE1394.

[Figure 3] Operation request block (OR
Diagram showing the configuration of B)

FIG. 4 is a diagram showing a configuration of a status block (SB).

FIG. 5 is a diagram showing a specific example of a procedure for transmitting print data and control data from a host device to a printer under communication control according to the principles of the present invention.

FIG. 6 is a diagram showing a specific example of a data communication procedure before and after a bus reset when the configuration of an IEEE1934 communication network in which a host device and a printer are connected is changed under communication control according to the principle of the present invention.

FIG. 7 is a flowchart showing a control flow of the host device when a transmission request for print data, control data, or the like is generated.

FIG. 8 is a flowchart showing a control procedure of a host device when transmitting an ORB.

FIG. 9 is a flowchart showing a control procedure of the host device immediately after the bus reset.

FIG. 10 is a flowchart showing a printer control procedure when an ORB is received.

FIG. 11 is a flowchart showing a printer control procedure upon completion of reception of one-block data.

FIG. 12 is a flowchart showing a printer control procedure when a timeout-out event occurs during data reception in D_Ch.

FIG. 13 is a flowchart showing a control procedure of the host device when SB is received.

[Explanation of symbols]

10 Printer Driver 20 Printer Utility 50 IEEE1394.3 Controller 100 Operation Request Block (OR
B) 110 data buffer 120 register 200 status block (SB)

Claims (4)

[Claims] 1. A device for controlling data communication between devices on a communication network, comprising: a receiving device, a data receiving means for gradually receiving data of a predetermined data size from a transmitting device; and the receiving device. With the progress of receiving the data,
A received data size storage unit that updates and stores the received data size or the unreceived remaining data size, and immediately after the configuration of the communication network changes, the receiving side device and the transmitting side device perform a bus reset. Topological reconstructing means for reconstructing the topology of the communication network by means of the transmitting device, immediately after the reconstruction of the topology, means for sending a data reception request again to the receiving device, and the receiving device. Immediately after rebuilding the topology, a determination is made to receive the data reception request from the transmission side device and determine whether the data requested by the reception request is the same as the data received immediately before the bus reset. As a result of the judgment in the receiving side device, the requested data is data received immediately before the bus reset. If the same data, using the received data size or the remaining data size stored immediately before the bus reset, of the requested data, skip the data portion of the received data size from the beginning, A control device for inter-device data communication, comprising data re-reception means for selectively receiving a subsequent unreceived data portion. 2. The transmission side device adds a signature for distinguishing each data transmitted to the reception side device from other data, which is provided immediately after reconstruction of the topology. When the data requested by the reception request is the same data as the data immediately before the bus reset, a signature assigning unit that gives the same signature as the data immediately before the bus reset to the requested data is further included. The determining means of the receiving device compares the signature of the data received immediately before the bus reset with the signature of the requested data, so that the requested data is received immediately before the bus reset. The control device for inter-device data communication according to claim 1, wherein it is determined whether or not it is the same as the data. 3. As a result of the judgment in the receiving side device,
2. The method according to claim 1, further comprising means for gradually receiving all of the requested data when the requested data is different from the data received immediately before the bus reset.
A control device for inter-device data communication described. 4. A method for controlling data communication between devices on a communication network, the receiving device gradually receiving data of a predetermined data size from the transmitting device; Then, as the reception of the data progresses,
Updating and storing the received data size or the unreceived remaining data size; and immediately after the configuration of the communication network changes, the receiving side device and the transmitting side device perform a bus reset to perform communication of the communication network. Reconstructing the topology, in the transmission side device, immediately after the reconstruction of the topology, sending a data reception request again to the reception side device, in the reception side device, immediately after the reconstruction of the topology, Receiving the data reception request from the transmission side device, determining whether the data requested by the reception request is the same data received immediately before the bus reset, and the reception side device. If, as a result of the determination, the requested data is the same as the data received immediately before the bus reset, the Using the received data size or the remaining data size stored immediately before the bus reset, of the requested data, skip the data part of the received data size from the beginning, and the subsequent unreceived data part. A method for controlling inter-device data communication, comprising the step of selectively receiving the data.