JP2001282488A - Printing control device, network printer and method for controlling printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten printing time and to suppress the increase of traffic volume of a network channel by simultaneously performing printing processing by plural network printers connected to a network environment. SOLUTION: At least, one of plural network printers is allowed to participate in a prescribed multicast address, printing data are transmitted to the multicast address as a packet by multicast and the packet transmitting/receiving state of the network printer participating in the multicast address is monitored to control the transmission/stand-by, retransmission, etc., of the packet to the multicast address.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a print control apparatus, a print control method, and a network printer used for the same which can perform broadcast transmission and reception in a network environment.

[0002]

2. Description of the Related Art Conventionally, when printing a plurality of copies from a single host computer in a network environment, the following method is employed.

First, as a first method, there is a method of transmitting print data from a host computer to one network printer by designating the number of print copies and printing the data.

Next, as a second method, there is a method in which print data is sequentially transmitted from a host computer to each of a plurality of network printers, and printing is performed in each of the plurality of network printers.

[0005]

However, in the first method, if the printing speed of the network printer is not sufficient, it takes a long time to complete printing of a plurality of copies.

Further, in the second method, it is necessary for the host computer to sequentially send print data to each of the network printers in charge of printing, and there is still a problem that the time required for completing printing is long. Was. Furthermore, in this method, since a plurality of duplicate print data flows on the network path, the traffic volume of the network path increases, and there is a possibility that other processing in the network environment may be hindered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables printing to be performed simultaneously and in parallel by a plurality of network printers connected to a network environment. An object of the present invention is to provide a print control device, a print control method, and a network printer used for the same, which can suppress an increase in traffic volume.

[0008]

According to a first aspect of the present invention, there is provided a print control apparatus, wherein at least one of the network printers participates in a predetermined multicast address, and print data is transmitted to the multicast address. Means for transmitting a packet to the multicast address, and controlling the transmission, standby, retransmission, etc. of the packet to the multicast address by monitoring the state of transmission and reception of the packet in the network printer participating in the multicast address. Means.

Thus, it is only necessary to perform data transmission by multicast to the network printer participating in the multicast address, and it is possible to reduce the printing time and suppress the increase in traffic volume. In addition, since transmission and reception of print data packets are monitored and transmission and the like are controlled, reliable data transmission can be performed.

According to a second aspect of the present invention, there is provided a print control apparatus including a search unit for searching for a network printer that can participate in the predetermined multicast address.

[0011] Thus, by searching for a printer that can participate in the multicast address, a network printer capable of reliably printing print data can be found, and subsequent printing of print data and the like can be reliably performed. Can be processed.

According to a third aspect of the present invention, there is provided a print control apparatus.
There is provided a network printer selecting means for selecting a network printer actually used for printing from the network printers obtained by the searching means.

Thus, a network printer to be used can be selected from the network printers detected by the search means. In the case where this selection can be made by the user, printing can be performed by an appropriate network printer in consideration of the location of the network printer and the like.

[0014] According to a fourth aspect of the present invention, there is provided a print control apparatus.
There is provided a print copy setting means for setting the number of copies to be printed by the network printer selected by the network printer selection means.

Thus, the number of print copies can be appropriately allocated according to the printing speed of the selected network printer, and the printing speed can be optimized.

According to a fifth aspect of the present invention, there is provided a print control apparatus comprising:
Operation defining means for preliminarily defining the operation of transmitting, waiting, retransmitting, etc. the packet to the multicast address in the control means in accordance with the state of transmission and reception of the packet in the network printer participating in the predetermined multicast address. With.

Thus, it is possible to define in advance how to control transmission and reception of packets when a failure or the like occurs in transmission and reception in the network printer.

According to a sixth aspect of the present invention, there is provided a print control apparatus.
When the control unit does not receive, within a predetermined time, an acknowledgment that the packet transmitted by the transmission unit has been received from all of the network printers participating in the multicast address, the control unit transmits the packet to the network printer. Means are provided for retransmitting to a multicast address by multicast.

Accordingly, when a failure occurs in at least one of the network printers and a positive response indicating that the packet has been received cannot be made,
The packet can be retransmitted to ensure the printing process.

According to a seventh aspect of the present invention, there is provided a print control apparatus.
If the control means does not receive, within a predetermined time, an acknowledgment that the packet transmitted by the transmitting means has been received from any of the network printers participating in the multicast address, Means for transmitting the next packet to the multicast address by multicast without retransmitting the packet.

In this way, when a failure that cannot be immediately recovered in at least one of the network printers occurs, the next packet is transmitted without retransmission so that the print processing in another network printer is not interrupted. it can.

A print control device according to a eighth aspect of the present invention comprises:
The control means receives, within a predetermined time, an acknowledgment that the packet transmitted by the transmission means has been received from all the network printers participating in the multicast address due to a communication failure in the network. If the packet has not been transmitted, means for retransmitting the packet to the multicast address by multicast is provided.

Thus, even when at least one of the network printers is a communication failure,
Packets can be retransmitted to ensure the printing process.

According to a ninth aspect of the present invention, there is provided a network printer including a network interface connected to a network, and a function of participating in a specific multicast address according to an instruction of a print control device connected to the network or independently. With.

Thus, a specific network printer can participate in a predetermined multicast address.

The network printer according to the tenth aspect of the present invention rejects the participation request from the print control device when the network printer has already participated in another multicast address in response to the participation request from the print control device. With.

Thus, when the network printer uses a predetermined multicast address, it is possible to prevent the network printer from being rejected from joining and becoming a duplicate state.

[0028] In the network printer according to the present invention, an acknowledgment that the packet of the print data transmitted by the print control device has been received, a negative acknowledgment that the packet cannot be received, and a prompt to resend the packet. A means is provided for notifying any of the retransmission responses to the print control device.

Thus, the network printer that has received the packet can notify the print control device of the situation by giving one of a negative response, an acknowledgment, and a retransmission response. Can be accurately performed.

A network printer according to a twelfth aspect of the present invention has a function of leaving a specific multicast address in response to an instruction from a print control device.

Thus, when a network printer participating in a predetermined multicast address has a failure or when the printing process is completed, the network printer can leave the multicast address.

A print control method according to a thirteenth aspect of the present invention provides a print control method in which at least one of the network printers participates in a predetermined multicast address, and transmits print data to the multicast address as a packet by multicast. The network printer participating in the multicast address monitors the state of transmission and reception of the packet, and controls transmission, standby, retransmission, and the like of the packet to the multicast address.

Thus, the data may be transmitted by multicasting to the network printer participating in the multicast address, and the printing time can be reduced and the traffic volume can be suppressed. Moreover, since transmission and reception of print data packets are monitored and transmission and the like are controlled, reliable data transmission can be performed.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the printing system according to the present embodiment has a host computer 1 as a printing control device.
And printers A to H as network printers are connected on a network.

In this embodiment, the communication protocol is TCP / IP (Transmission Control Protocol / In).
Internet Protocol). However, another protocol capable of multicasting may be used.

In the TCP / IP implementation, UDP (User
IP (Internet Protocol) multicast by Datagram Protocol is used. Supplementally use unicast or broadcast.

An application program is installed in the host computer 1 so as to transmit print data to the network printers by multicast and to cause each printer to print the data. 1 functions as each unit described below.

First, the host computer 1 sends print data generated by the host computer 1 or obtained by the host computer 1 from another device to a network (LAN) using a broadcast address or a specific multicast address as a destination address. It functions as a transmitting means for transmitting.

Next, the host computer 1 functions as a search means for searching a network for a network printer having the ability to print the print data to be printed without any problem.

In the system of this embodiment, since the same print data is transmitted to a plurality of network printers simultaneously, it is necessary to find a plurality of network printers capable of reliably printing the print data. For example, the same print data cannot be transmitted to a network printer having only PostScript and a network printer having only PCL (Printer Control Language). Also, even a network printer that has all the capabilities may not be able to be used immediately due to offline status, etc.
You also need to check the status of the network printer.

There are the following search condition items in this search means. (A) Whether or not the printing function of the printing system of the present embodiment is supported (b) Corresponding size of paper (for example, LETTER) (c) Number of printed pages (for example, 50) (d) Orientation portrait (so-called (E) resolution (e.g., 600 dpi) (f) presence / absence and version of PDL (Page Description Language) (e.g., PCL5) (g) color / monochrome compatible (e.g., color printing) (f) printer status (e.g., immediately Or not)

The combination of these search conditions is SNMP
(Simple Network Management Protocol) or broadcasting of a unique implementation protocol may be used to directly inquire a network printer on the network. X.50, which is configured by a network printer voluntarily or by an administrator inputting information.
0 (International Recommendation) and SLP (Service Location Protocol)
l) and LDAP (Lightweight Directory Access Protocol)
ol) or the like, the capability of the network printer is registered in a directory service, and the host computer 1 uses this directory service to search for a network printer that satisfies the conditions.
The host computer 1 obtains, as a result of the search, the IP address of the network printer, the name of the network printer, the location information of the network printer, and the like.

Further, the host computer 1 functions as a printer selecting means for selecting a network printer actually used for printing from the network printers searched by the searching means.

In this embodiment, instead of sending print data to network printers on all networks having the ability to print desired print data, the number of copies to be printed and the location where the user is physically located are determined. The user can select whether to select a network printer close to or to select only a high-speed network printer. The host computer 1 displays a display list listing the network printer names, IP addresses, installation locations, and the like of the network printers found by the search means, and from this display list, the network actually used for printing. The user can select a printer.

Further, the host computer 1 functions as a print copy number setting unit that sets an independent print copy number for each of the network printers selected by the printer selection unit.

Assume that the printing speeds of the network printers selected by the printer selecting means are, for example, 10 ppm and 20 ppm. A 20 ppm network printer can print at twice the printing speed as a 10 ppm network printer. If each network printer prints a part uniformly, the network printer of 20 ppm is 10 ppm
A waiting time is generated as the printing process proceeds. Therefore, if the network printer of 20 ppm is set to print twice as many copies as the network printer of 10 ppm, it is possible to print efficiently in time. Alternatively, the printing speed may be checked when the capability of the network printer is checked by the search means, and the system may automatically set an optimized number of copies. For example, when the user wants to print five copies in total, assuming that the user selects three 10 ppm network printers and a 20 ppm network printer by the printer selection means, the system automatically sets the number of print copies in the 20 ppm network printer to 2, 10 ppm. It is also possible to set the number of copies of each of the network printers to one. The setting of the number of print copies to each network printer is instructed by unicast to each network printer prior to multicast transmission of print data.

Further, the host computer 1 functions as a behavior selecting means for selecting a behavior of the host computer when a failure occurs in the network printer during printing and printing data cannot be received.

In the printing system according to the present embodiment, the same print data is simultaneously transmitted to network printers in a specific multicast address group. Print data is divided into packets and transmitted to each network printer. Each network printer informs the host computer 1 that each packet has been normally received. For example, it is assumed that printing is performed simultaneously on three network printers A, B, and C, and the print data is divided into a total of 20 packets. It is assumed that a failure such as running out of paper occurs in the network printer B when the tenth packet is received, and data cannot be received any more. The network printer A and the network printer C return an acknowledgment to the host computer 1 indicating that the tenth packet has been normally received, but the network printer B explicitly has a negative acknowledgment that the tenth packet could not be received. Or return no acknowledgment until the fault is corrected. In this case, the host computer 1 cannot transmit the data of the next packet, and the network printer A and the network printer C
Will be stopped until the failure of the network printer B is recovered. When such a state occurs, the user can provide a choice of what to do with the computer 1. For example, the following two modes can be considered.

(A) Wait forever until all network printers are ready to receive. Select this mode if you want to print all copies with a single print command. The user needs to take immediate action when a failure occurs in the network printer. However, a catastrophic failure that cannot be recovered immediately is network printer B.
Therefore, even if this mode is selected, it is possible to give up printing by the network printer B and switch to continue printing by the other network printers A and C on the way. Preferably.

(B) Wait for a set time until all network printers recover. This mode is selected when the faulty network printer is to be discarded and printing is to be continued only with the network printer that continues to operate normally. In this mode, when a failure occurs in a certain network printer and an acknowledgment of a packet is not returned, the time set by the user or set in advance as a default in the system (T
In this mode, the network printer waits for 1), and if no acknowledgment is returned even after the elapse of the standby time (T1), printing by the network printer is abandoned and the next packet is transmitted. The network printer that has received the next packet without returning an acknowledgment determines that it has been truncated by the host computer, discards subsequent packets, and does not print. In this case, the host computer 1 functions as a retransmitting unit that retransmits the print data every standby time (T1).

Next, the host computer 1 functions as a joining unit for joining all the network printers selected by the printer selecting unit in accordance with an instruction from the host computer 1 to a specific multicast address.

Only when necessary, the network printer
It is desirable to be able to receive multicast data. For example, if the network printer in the printing system according to the present embodiment receives multicast data for printing in advance, the network printer should print or discard it according to a command in the print data. Assume that it is configured to determine

In this case, when the network printer does not print the print data from the host computer 1,
Receives unnecessary print data, determines that it is unnecessary, and
The discarding process becomes an overhead, which may hinder execution of normal printing from another host computer to the printing apparatus.

Therefore, in order to make all network printers selected by the user by the printer selecting means ready for multicast reception, a group of multicast addresses used for printing from the host computer 1 to each network printer is used. Is sent by unicast.

Further, if the host computer 1 does not receive an acknowledgment from the network printer even after the elapse of a predetermined standby time (T2), the host computer 1
Functions as resending means for automatically resending print data.

The host computer divides the print data into packets and transmits the multicast data as the destination address. The transmitted packet is received by all the network printers on the network that have joined the multicast group by the joining means.

Each packet has a sequence number. Basically, when a packet having a certain sequence number is transmitted, the packet has the next sequence number unless an acknowledgment for the sequence number is received from all printing apparatuses. Packets cannot be transmitted.

A packet may be lost due to some trouble in network communication. In this case, the print data transmitted from the host computer 1 is not normally received by all or some of the network printers, and the acknowledgment transmitted from the network printer is completely or partially correct.
Are not received.

In this case, the two cases can be recovered by the host computer 1 retransmitting the print data of the same sequence number. The number of retransmissions to be performed or the retransmission after the elapse of the standby time (T2) is a system specified value,
The setting may be performed by a user using a setting unit.

However, in the case where a predetermined waiting time (T1) has elapsed according to the mode set by the above-described behavior selecting means, and the network printer that did not return an acknowledgment gives up printing and proceeds to the transmission of the next packet. There is also.

Next, a control program capable of responding to a transmission request from the host computer 1 is installed in the network printers A to E in the printing system of the present embodiment so as to be executable, and the control program is started. Thus, the network printers A to E
It functions as the following means.

First, the network printers A to E function as receiving means for receiving print data transmitted on the broadcast address or addressed to a specific multicast address.

The network printers A to E
Indicates that if the network printer is already participating in a specific multicast address, a new host computer 1
Functions as a rejection unit that rejects a request for participation in a specific multicast address from.

Among the network printers A to E that have received the instruction from the participation means, the printers that can respond are ready to receive the data of the requested multicast address, and inform the host that the reception is possible. A response is sent to the computer 1. But,
If the multicast address requested by the host computer 1 has already been used, the host computer 1 sends a response to the effect that the participation request is rejected.

Each of the network printers A to E
Means for notifying the host computer 1 that the packet of the print data has been normally received, or means for notifying the host computer that the packet cannot be received any more.
Alternatively, it functions as means for requesting the host computer to retransmit data.

Each of the network printers A to E returns an acknowledgment when the print data of the sequence number is normally received. However, if the receiving buffer is in a state of being full or out of paper and cannot accept print data any more, no acknowledgment is returned.
In such a state, a negative acknowledgment indicating that it cannot be explicitly received can be returned. At this time, when returning a negative response, a reason for giving a negative response can be added.
For this reason, the host computer can notify the operating user of the reason why printing is interrupted. It is assumed that the network printers A, D, and E can recognize that a bad packet has been received for some reason. In this case, by actively sending a resend request to the host computer 1 from the network printers A to E, the packet resend process can be promptly performed without waiting for the above-described waiting time (T2).

Further, the network printers A to E function as means for canceling the participation of a specific multicast address set by an instruction from the host computer 1 as the participation means.

The host computer 1 makes a unicast request individually to the network printer to release from the multicast group in which the network printer participates. The network printer receiving this request leaves the multicast group.

Next, how the print data processing of the present embodiment is performed by the host computer 1 and the network printer functioning as the respective units described above will be specifically described below.

First, the host computer 1 searches the network for a network printer capable of printing the print data to be printed without any problem.

That is, the host computer 1
(A) a printer that supports the printing function of the printing system of the present embodiment, and (b) LETTE
R size, (c) 50 printable pages, (d) portrait orientation portrait, (e) 600 dpi resolution support, (f) PDL PCL5 , (G) printers that support color printing, (f) printers whose status is ready, and network printers that satisfy all of the following conditions to request the host computer to return a response. Is broadcast on the network (FIG. 8: step S1). Then, it waits for a reply (FIG. 8: step S2).

On the other hand, the printer in the reception waiting state (FIG. 11: step S30) receives a request by broadcasting the search condition (FIG. 11: step S31;
If the search condition is met, information about its own printing capability, such as its own IP address, printer name, and location information printing speed, is transmitted to the host computer (FIG. 11: step S32). FIG. 2 shows an example in which five printers A, B, C, D, and E respond.

Next, when there is a reply from the printer and the returned packet is valid (FIG. 8: step S3; YES), the host computer 1 uses the information transmitted from the printer as an information list. It is stored and displayed in a list (FIG. 8: step S5). However, when there is no valid packet (FIG. 8: step S3; NO), a predetermined error process is performed (step S4).

FIG. 3A shows an example in which information transmitted from the printers A, B, C, D and E is displayed as an information list 10.

Next, the host computer 1 waits for the user to input the number of copies (FIG. 8: step S6). The setting of the number of copies is performed in the following procedure.

First, the user looks at the list display of the information list 10 and confirms location information, printing speed, and the like.
A printer used for actual printing is selected from the searched printers A, B, C, D and E. FIG. 3B shows an example in which the printer A, the printer D, and the printer E are selected. The selected printer is displayed as distinguished from non-selected printers as shown in FIG. FIG. 3B shows a printer whose hatched printer is selected.

Next, the user sets and inputs the number of copies to be printed on the selected printer. Here, since the printing speed of the printer E is twice that of the other printers A and D, the number of print copies is set and input to twice that of the other printers (FIG. 3).
(B)). When the setting is completed, the user clicks the [OK] button 11 of the information list 10 shown in FIG. 3B or presses the ENTER key on the keyboard.

Next, when the host computer 1 detects the input such as the click of the [OK] button as described above (FIG. 8: step S7; YES), the host computer 1 displays a process selection screen at the time of a printing failure (FIG. 8). : Step S8), and waits for an input of a process selection by the user (FIG. 9: Step S9).
FIG. 4 shows a display example of the selection screen 20.

The user selects this screen 20
When a failure occurs in the printer that is performing printing and the transmitted print data cannot be received, the host computer 1 sets and inputs how to perform processing. The user checks either the button 21 for selecting “Wait for recovery from failure.” Or the button for selecting “Continue printing without waiting for recovery from failure if the set time is exceeded.” Insert When the latter is checked, the waiting time is entered in the text box 23 displayed below. In the example of FIG. 4, 10 seconds is input.

When the host computer 1 detects that the above input has been made (FIG. 9: Step S10;
YES), a join request (joinGrou) to join the printer selected by the user to a specific multicast address.
p) by unicast (FIG. 9: Step S1)
1) Wait for a reply from the printer for a predetermined time (for example, 2 seconds) (FIG. 9: step S12).

In the example shown in FIG. 5, a join request (joinGrou) is issued to the printers A, D, and E to join the multicast address (239.245.22.22).
p) is transmitted by unicast.

On the other hand, the printer that has received the above request (FIG. 11: step S35; YES) determines whether or not it has already joined the designated multicast address (FIG. 1).
1: Step S36), when not participating in the designated multicast address (FIG. 11: Step S3)
6; NO), participates in the multicast address (FIG. 11: step S37), and returns an OK signal to the effect that the participation has been completed to the host computer 1 (FIG. 11: step S39). Also, the sequence number 1 is entered in the sequence number register seqP managed by the printer (FIG. 1).
1: Step S40).

In the example shown in FIG. 5, the printers A, D, and E return an OK signal to the host computer 1, and the printers A, D, and E send packets transmitted to the multicast address. Can be received.

However, if it is already participating in the specified multicast address (FIG. 11: Step S3
6; YES), the printer now rejects participation N
The G signal is transmitted to the host computer 1 (FIG. 11: step S38).

Upon receiving the reply from the printer, the host computer 1 determines whether or not an OK packet has been received (FIG. 9: step S13).
G packet is received (FIG. 9: Step S1).
3; NO), a dialog indicating this fact is displayed to the user (FIG. 9: step S14), and the user waits for the click or press of the OK button (FIG. 9: step S1).
5).

However, when OK packets are received from all the printers (FIG. 9: step S13; YE
S), a command for specifying the number of print copies is transmitted to each printer by unicast (FIG. 9: step S16).

On the other hand, each printer confirms reception of the copy number setting command (FIG. 11: step S3).
3; YES), the number of copies is set according to the command (FIG. 11: step S34).

Next, the host computer 1 divides the print data into packets, and puts a sequence number 0 in the packet sequence number register seqh managed by the host computer (FIG. 10: step S17). Then, it is determined whether or not the transmission of all the print data packets is completed (FIG. 10: step S18). If the transmission of all the packets is not completed (FIG. 10: step S1).
8; NO), the value of the sequence number register seqh is incremented (FIG. 10: step S20), and the packet of the print data with the sequence number 1 is transmitted by multicast (FIG. 10: step S21). Further, the host computer 1 transmits the standby time T
Start counting 1 and T2. Then, a reply packet from the printer is received (FIG. 10: Step S2).
2).

FIG. 6A shows a sequence number register se.
An example is shown in which a value of qh, that is, a packet of print data with a sequence number of 1 is transmitted to the multicast address (239.245.22.22) by multicast.

On the other hand, when the printer confirms the reception of the multicast print packet (FIG. 12: step S41; YES), it determines whether or not the received packet is normal (FIG. 12: step S42). (FIG. 12: Step S42; YES), it is determined whether the sequence number of the packet is smaller than the value of the register seqp (FIG. 12: Step S44). If it is small (Fig. 1
2: Step S44; YES), the received packet is ignored because it is not a packet to be processed at present. However, the packet sequence number is in the register seqp
(FIG. 12: Step S44;
NO), it is determined whether the sequence number of the packet is larger than the value of the register seqp (FIG. 12: step S45).
If not large (FIG. 12: Step S45; N
O), the received packet is processed (FIG. 12: step S47). More specifically, print data is stored and expanded in a memory provided in the printer, and a printing process is executed based on the expanded data. When the packet processing is completed, an acknowledgment (ACK) is returned to the host computer 1, and the value of the register seqp is incremented (FIG. 12: step S48).

FIG. 6A shows an example in which each of the printer A, the printer D, and the printer E returns an acknowledgment (ACK) to the host computer 1 in this manner. In the case of FIG. 6A, all printers are AC
K is returned within 5 seconds.

Next, the host computer 1 that has received the reply from the printer checks whether the reply is a retransmission request (FIG. 10: step S23), and if it is not a retransmission request (FIG. 10: step S23). (S23; NO), and after confirming whether or not there is an affirmative response from all printers (FIG. 10: step S24; YES), the transmission process is continued.

That is, it is confirmed that transmission of all packets has not been completed yet (FIG. 10: step S18; N).
O), the value of the register seqh is incremented (FIG. 1)
0: Step S20), and transmits the packet of the next sequence number (FIG. 10: Step S21).

FIG. 6B shows an example in which a packet having a sequence number of 2 is transmitted from the host computer 1 to a multicast address, and the printers A and D promptly return an ACK in response to the packet. However, the printer E received the packet (FIG. 12:
(Step S41; YES) Since it is detected that the received packet is bad for any reason (FIG. 12: Step S42; NO), a resend request (RESEND) for the packet is returned to the host computer (FIG. 12). 1
2: Step S43).

On the other hand, the retransmission request (RESEN)
The host computer 1 that has received D) (FIG. 10: step S23; YES) transmits the packet of the current sequence number again (FIG. 10: step S21) and receives a reply packet from the printer (FIG. 10: Step S
22).

The printer that has received the retransmitted packet determines whether the packet is normal (step S42 in FIG. 12).
Step S42; YES), the packet is processed according to the procedure described above (FIG. 12: steps S44 to S4).
8).

In the example shown in FIG. 6C, a packet having a sequence number of 2 is retransmitted by multicast from the host computer 1 and the printer E receiving the packet transmits an ACK.
Shows an example in which is returned. In this case, since the value of the sequence register seqp is 3 in the printers A and D which have already returned ACK, as shown in step S44 of FIG. Sequence number is sequence register seqp
(FIG. 12: Step S4)
4; YES), ignore the retransmitted packet.

As described above, in this embodiment, when a packet received by the printer is defective,
Since the resend request is configured to be returned to the host computer, communication with correct data can be reliably performed between the host computer and the printer.

Further, in the printer, even if the received packet is normal, it may take a long time to process the packet due to circumstances such as an empty buffer or a paper jam. In this case, a wait request (WAIT) requesting that the user wait for transmission of the next packet can be issued.

Further, when some trouble occurs in the communication of the network, there is a possibility that the packet is lost. As a result, the case where the print data transmitted from the host computer 1 is not normally received by all or some of the printers, and the case where all or a part of the acknowledgment transmitted from the printer are normally transmitted to the host computer 1 Two phenomena can occur: the case of no reception.
Thus, in the present embodiment, not only when there is a retransmission request (RESEND) as described above, but also when no acknowledgment is returned from all the printers even after a certain time (T1) elapses, the predetermined number of times is returned. It is configured to perform retransmission processing.

More specifically, when a packet having a predetermined sequence number is transmitted from the host computer 1 to the multicast address (FIG. 10: step S21), and there is at least one printer that does not return an acknowledgment (FIG. 1).
0: Step S22 to Step S23; NO to Step S24; NO), until a certain time (T1) elapses (FIG. 10: Step S25; NO to Step S26; N).
O), wait for an acknowledgment to be returned (FIG. 10: step S22 to step S23; NO to step S24; N)
O to step S25; NO to step S26; NO).
However, when a certain time (T1) has elapsed (see FIG. 1).
0: Step S26; YES), the packet having the predetermined sequence number is retransmitted to the multicast address (FIG. 10: Step S21).

In the example shown in FIG. 6D, as a result of transmitting a packet having a sequence number of 3 to the multicast address from the host computer 1, ACKs are returned from the printers D and E. No reply has been made.

Therefore, the host computer 1 waits for a reply from the printer A for 5 seconds as a fixed time (T1). Then, as shown in FIG.
The packet whose sequence number is 3 is retransmitted to the multicast address. Therefore, if the failure in the network communication is resolved during the above five seconds, the printer A
From ACK. In the printers D and E that have already returned ACK, the value of the sequence register seqp is 4, so that the sequence number of the retransmitted packet is set in the sequence register as shown in step S44 in FIG. It is determined that it is smaller than the value of seqp (FIG. 12: step S44; YES), and the retransmitted packet of sequence number 3 is ignored.

Even when the retransmission processing is performed at regular intervals (T1) as described above, the behavior in the case where the failure in the communication of the network is not solved is selected on the selection screen 20 for selecting the behavior as described above. I do.

When the mode of waiting for the recovery from the failure is selected, the resending process is repeated every fixed time (T1) until ACKs are returned from all the printers.

However, in this embodiment, if no ACK is returned from all the printers even after the set time (T2) has elapsed, it is assumed that the mode in which printing is continued is selected. When this mode is selected,
Simultaneously with the transmission of the packet, a timer for counting the fixed time (T1) and a timer for counting the set time (T2) are started. Then, the predetermined time (T
1) While repeating the retransmission processing for each (FIG. 10: Step S21 to Step S22 to Step S23; NO to Step S24; NO to Step S25; NO to Step S)
26; NO / YES), if the set time (T2) has elapsed without an ACK being returned from all printers (FIG. 10: step S25; YES), a packet of the next sequence number is transmitted (FIG. 10: step S25; YES). FIG. 10: Step S20 to Step S21).

In the examples shown in FIGS. 7A, 7B and 7C, first, the sequence number 4
To the multicast address. On the other hand, ACK is returned from the printers D and E, but ACK is not returned from the printer A.

Therefore, the host computer 1 waits for a reply for the fixed time (T1 = 5 seconds), and retransmits the packet of sequence number 4 to the multicast address after the fixed time (T1 = 5 seconds). However, also in this case, since the ACK is not returned from the printer A, the printer A again waits for the above-mentioned fixed time (T1 = 5 seconds). However, the next fixed time (T1 = 5 seconds)
After the elapse of the set time (T2 = 10 seconds), the host computer 1 stops waiting for a reply from the printer A and transmits the packet of the next sequence number 5. As a result, in the following, when ACKs are returned from the printers D and E, it is determined that ACKs have been returned from all the printers.
The packet transmission processing described above will be continued.

Even if the failure is recovered at the subsequent timing and the printer A receives the packet transmitted to the multicast address, the printer A sets the sequence number of the packet to the sequence number at the time of occurrence of the failure. (FIG. 12: Step S45; YE)
S), printing is interrupted, and participation in the multicast group is interrupted (FIG. 12: step S46).

When the above packet transmission processing is performed and transmission of all print packets is completed (FIG. 10: step S18; YES), the host computer 1 releases the packet for canceling the multicast participation. Is transmitted to the multicast address (FIG. 10: step S19).

On the other hand, the printer that has received the packet for canceling the multicast participation (FIG. 12: Step S
41; NO to step S49; YES), the participation in the multicast group is interrupted, and the host computer 1
Returns OK indicating that the packet for canceling participation has been received (FIG. 12: step S50).

On the other hand, the host computer 1 determines whether or not OK has been returned from all the printers after transmitting the packet for canceling the participation in the multicast (FIG. 10: step S27). OK
Is returned (FIG. 10: Step S27; YE
S), the print data broadcast process ends (FIG. 10:
Step S28). However, if OK is not returned from all the printers (FIG. 10: step S27; N
O), the packet for canceling the participation in the multicast is retransmitted (FIG. 10: step S19). This retransmission may be limited by time or by the number of times as in the retransmission processing described above. Also,
If OK is not returned even after exceeding the predetermined limit, the processing may be temporarily stopped, and the retransmission processing may be restarted after a predetermined long time has elapsed.

In the example shown in FIG. 7D, the host computer 1 unicasts a release request (LeaveGroup) to the printer which has transmitted the request for joining (joinGroup) to the multicast address so as to release the participation. Send by The printer that has received the release request performs a release process. As a result, it is possible to prevent the occurrence of a functional failure of the network due to the continued participation, and to flexibly respond to the participation request from the host computer thereafter.

As described above, according to the present embodiment, since print data is broadcast by multicasting, printing of a plurality of copies can be performed quickly without imposing a load on other printers connected to the network. be able to.

[0116]

As described above, according to the first aspect of the present invention,
The print control device described above may perform multicasting to network printers participating in the multicast address, thereby reducing printing time and suppressing an increase in traffic volume, and monitoring transmission and reception of print data packets. Since transmission and the like are controlled, reliable data transmission can be performed.

According to the second aspect of the present invention, by searching for a printer that can participate in a multicast address, a network printer capable of reliably printing print data can be searched for. Thus, the subsequent printing of the print data and the like can be surely processed.

In the printing control apparatus according to the third aspect of the present invention, a network printer to be used can be selected from the network printers detected by the search means. In the case where this selection can be made by the user, printing can be performed by an appropriate network printer in consideration of the location of the network printer and the like.

In the printing control apparatus according to the fourth aspect of the present invention, the number of print copies can be appropriately allocated according to the printing speed of the selected network printer, and the printing speed can be optimized.

In the print control apparatus according to the fifth aspect of the present invention, it is possible to specify in advance how to control transmission and reception of packets when a failure occurs in transmission and reception in the network printer.

In the printing control apparatus according to the sixth aspect of the present invention, when a failure occurs in at least one of the network printers and a positive response indicating that the packet has been received cannot be made, the packet is transmitted to the network. Resend
The printing process can be assured.

According to the printing control apparatus of the present invention, when a failure that cannot be immediately recovered in at least one of the network printers occurs, the next packet is transmitted without retransmission and another network printer is transmitted. Can be prevented from being delayed.

In the print control apparatus according to the eighth aspect of the present invention, the printing place can be secured by retransmitting the packet.

In the network printer according to the ninth aspect of the present invention, a specific network printer can participate in a predetermined multicast address.

In the network printer according to the tenth aspect of the present invention, when the network printer uses a predetermined multicast address, it is possible to prevent the network printer from being rejected from participating and becoming in a duplicate state.

In the network printer according to the eleventh aspect of the present invention, the network printer having received the packet notifies the print control device of the status by responding any one of a negative response, an acknowledgment, and a retransmission response. Therefore, the subsequent processing by the print control device can be properly performed.

In the network printer according to the twelfth aspect of the present invention, a network printer participating in a predetermined multicast address can leave the multicast address when a failure occurs or after printing is completed.

In the print control method according to the thirteenth aspect of the present invention, it is only necessary to perform multicasting for network printers participating in the multicast address, and it is possible to reduce printing time and suppress an increase in traffic volume. Since transmission and reception of print data packets are monitored to control transmission and the like, reliable data transmission can be performed.

[Brief description of the drawings]

FIG. 1 is a network configuration diagram to which a printing system according to an embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a CRT display in the processing of the printing system according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating a CRT display in the processing of the printing system according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 8 is a flowchart illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 9 is a flowchart illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 10 is a flowchart illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 11 is a flowchart illustrating processing of the printing system according to the embodiment of the present invention.

FIG. 12 is a flowchart illustrating processing of the printing system according to the embodiment of the present invention.

[Explanation of symbols]

1 host computer 10 information list 20 selection screen A, B, C, D, E, F, G, H network printer T1 standby time (retransmission timeout time) T2 standby time (print failure occurrence timeout time) seqh Managed by host computer Sequence number register seqp Sequence number register of the packet managed by the printer

Continuing on the front page (72) Inventor Yasushi Fukasawa 15-1, Naeshiro-cho, Mizuho-ku, Nagoya, Aichi Prefecture Inside the Brother Industries, Ltd. (72) Inventor Masaaki Hibino 15-1, Nashiro-cho, Mizuho-ku, Nagoya, Aichi, Japan Within Industrial Co., Ltd. (72) Inventor Akihiro Furukawa 15-1 Naeshiro-machi, Mizuho-ku, Nagoya-shi, Aichi F-term (reference) 2C061 AP01 HJ06 HJ08 HN16 HQ01 5B021 AA01 CC09 EE02 KK03 NN22 5K030 GA03 GA13 HA08 HC14 JT03 LD02 9A001 BB01 BB03 BB04 CC06 DD13 FF03 HH34 JJ18 JJ35 KK42 LL05 LL09

Claims (13)

[Claims] 1. A joining unit for joining at least one of the network printers to a predetermined multicast address, a sending unit for sending print data to the multicast address as a packet by multicast, and joining the multicast address. Control means for monitoring the transmission / reception state of the packet in the network printer performing the control, and controlling transmission, standby, retransmission and the like of the packet to the multicast address. 2. The print control apparatus according to claim 1, further comprising a search unit that searches for a network printer that can participate in the predetermined multicast address. 3. A printing control apparatus according to claim 2, further comprising a network printer selecting means for selecting a network printer to be actually used for printing from the network printers obtained by said searching means. . 4. The print control apparatus according to claim 3, further comprising print number setting means for setting the number of copies to be printed by the network printer selected by the network printer selection means. 5. In accordance with a state of transmission and reception of the packet by the network printer participating in the predetermined multicast address, an operation of transmitting, waiting, retransmitting a packet to the multicast address by the control means is performed in advance. The print control device according to claim 1, further comprising an operation defining unit that defines the operation. 6. When the control means does not receive, within a predetermined time, an acknowledgment that the packet transmitted by the transmission means has been received from all of the network printers participating in the multicast address. 6. The print control apparatus according to claim 1, further comprising means for retransmitting the packet to the multicast address by multicast. 7. When the control means does not receive, within a predetermined time, an acknowledgment that a packet transmitted by the transmission means has been received from any of the network printers participating in the multicast address. 7. The print control apparatus according to claim 1, further comprising means for transmitting the next packet to the multicast address by multicasting without retransmitting the packet. 8. The control means sends an acknowledgment that the packet transmitted by the transmission means has been received from all of the network printers participating in the multicast address due to a communication failure in the network. 8. The print control apparatus according to claim 1, further comprising means for retransmitting the packet to the multicast address by multicast when the packet is not received within a predetermined time. 9. A network printer comprising a network interface connected to a network, and a function of participating in a specific multicast address in accordance with an instruction of a print control device connected to the network or independently. . 10. A system according to claim 1, further comprising means for rejecting a participation request from said print control apparatus when said print control apparatus has already joined another multicast address in response to a participation request from said print control apparatus. 9. The network printer according to item 9. 11. The print control apparatus according to claim 1, wherein the print control apparatus transmits an acknowledgment that the packet of the print data transmitted by the print control apparatus has been received, a negative acknowledgment that the packet cannot be received, or a retransmission response that prompts the retransmission of the packet. 11. The network printer according to claim 9, further comprising means for notifying the user. 12. The network printer according to claim 9, further comprising a function of leaving a specific multicast address in accordance with an instruction from the print control device. 13. A step of causing at least one of the network printers to participate in a predetermined multicast address, a step of transmitting print data as a packet to the multicast address by multicast, and participating in the multicast address. Monitoring the state of transmission and reception of the packet by the network printer, and controlling transmission, standby, retransmission, and the like of the packet to the multicast address.