1. A data processing apparatus able to communicate with an information processing apparatus via a network, comprising:
an acquisition unit configured to acquire packets flowing through the network;
a retransmission unit configured to perform data retransmission in a case where data transmission to the information processing apparatus via the network has failed;
a control unit configured to cause said acquisition unit to start acquiring packets; and
a setting unit configured to set a number of times the data retransmission can be performed by said retransmission unit,
wherein the data retransmission is performed a number of times not more than the number of times set by said setting unit, and said acquisition unit acquires packets at least when any of data retransmissions is performed.
2. The data processing apparatus according to claim 1, wherein before said retransmission unit starts performing the data retransmission, said control unit gives said acquisition unit an instruction to start acquiring packets, and
after said retransmission unit completes performing the data retransmission, said control unit gives said acquisition unit an instruction to terminate acquiring packets.
3. The data processing apparatus according to claim 2, further including:
an instruction unit configured to accept a manual instruction according to which said instruction unit gives said acquisition unit an instruction to start or terminate acquiring packets,
wherein the instructions given by said control unit to start and terminate acquiring packets are each processed preferentially to the instructions given by said instruction unit to start and terminate acquiring packets.
4. The data processing apparatus according to claim 1, further including:
a selection unit configured to select packet acquisition with filter setting in which filtering is applied during the packet acquisition or packet acquisition without filter setting in which the filtering is not applied during the packet acquisition,
wherein said selection unit selects the packet acquisition with filter setting in a case where the data retransmission to be performed by said retransmission unit is any of a first to a predetermined N-th data retransmission, and
said selection unit selects the packet acquisition without filter setting in a case where the data retransmission to be performed by said retransmission unit is any of (N+1)-th and subsequent data retransmissions.
5. A control method for a data processing apparatus able to communicate with an information processing apparatus via a network, comprising:
an acquisition step of acquiring packets flowing through the network;
a retransmission step of performing data retransmission in a case where data transmission to the information processing apparatus via the network has failed;
a control step of starting packet acquisition in said acquisition step; and
a setting step of setting a number of times the data retransmission can be performed in said retransmission step,
wherein the data retransmission is performed a number of times not more than the number of times set in said setting step, and packets are acquired in said acquisition step at least when any of data retransmissions is performed.
6. A non-transitory computer-readable storage medium storing a program for causing a computer to execute the control method as set forth in claim 5.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A coordinate input apparatus for making an input by bringing a pointing device into contact with an input area of an apparatus main body,
said pointing device comprising:
a timer configured to generate a transmission cycle by timekeeping;
a detection unit configured to detect the presenceabsence of an input instruction according to the presenceabsence of contact of said pointing device with the input area; and
a transmission unit configured to transmit information including the input instruction to the apparatus main body via an optical communication in accordance with the transmission cycle generated by said timer when said detection unit detects the presence of the input instruction, and to skip transmission to the apparatus main body when said detection unit detects the absence of the input instruction,
wherein when said detection unit detects the presence of the input instruction, and then detects the absence of the input instruction, said timer continues timekeeping of the transmission cycle during a predetermined holding period, and
when said detection unit detects the absence of the input instruction, and then detects the presence of the input instruction within the holding period, said transmission unit performs transmission according to the transmission cycle generated based on timekeeping continued by said timer.
2. The apparatus according to claim 1, wherein said detection unit is further configured to detect the presenceabsence of an input instruction generated upon pressing of a switch arranged on a side surface of said pointing device.
3. The apparatus according to claim 1, wherein said transmission unit is further configured to transmit at least information indicating the presenceabsence of the input instruction and device identification information of said pointing device as the information including the input instruction.
4. The apparatus according to claim 3, further comprising a plurality of said pointing devices which respectively allow to make inputs to the input area, said plurality of pointing devices having different transmission cycles generated by the respective timers.
5. The apparatus according to claim 1, wherein said transmission unit performs transmission to the apparatus main body as the optical communication by emitting light according to the information including the input instruction.
6. The apparatus according to claim 5, further comprising:
a light projecting unit configured to perform a light projection to the input area;
a light receiving unit configured to detect a light amount distribution of reflected light as a result of the light projection to the input area;
a coordinate calculation unit configured to calculate a coordinate position where the reflected light is interrupted by said pointing device on the input area, based on a difference between the light amount distribution detected by said light receiving unit and a light amount distribution detected without any light projection; and
a light projection control unit configured to control a light projection cycle so as to avoid the light projection by said light projecting unit from being superposed with a light emission of said transmission unit based on the information including the input instruction transmitted by said transmission unit from said pointing device.
7. The apparatus according to claim 6, wherein said light projecting unit and said light receiving unit are respectively arranged at each of two corners of the input area, and
said light receiving unit detects a light amount distribution of reflected light obtained by retro-reflecting light projected from said light projecting unit by a peripheral portion of the input area.
8. A method for controlling a pointing device wherein an input is made by bringing the pointing device into contact with an input area of a main body of a coordinate input apparatus,
wherein said pointing device comprising a timer configured to generate a transmission cycle by timekeeping,
said method comprises the steps of:
detecting the presenceabsence of an input instruction according to the presenceabsence of contact of said pointing device with the input area;
transmitting information including the input instruction to the apparatus main body via an optical communication in accordance with the transmission cycle generated by said timer when the presence of the input instruction is detected, and skipping transmission to the apparatus main body when the absence of the input instruction is detected;
making the timer continue timekeeping of the transmission cycle during a predetermined holding period, when the presence of the input instruction is detected and then the absence of the input instruction is detected; and
transmitting according to the transmission cycle generated based on timekeeping continued by said timer, when the absence of the input instruction is detected and then the presence of the input instruction is detected within the holding period.
9. A storage medium storing a program for controlling a computer to function as respective units of a coordinate input apparatus according to claim 1 when said program is executed by the computer.