Data transfer device

A data transfer apparatus that (a) receives from an upper station (i) a first type of data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station and being composed of a plurality of repeat data packets, and (ii) a second type of data stream that includes at least one null data packet that is a dummy data packet that does not include data to be reproduced and displayed, and (b) transfers the received repeat data to a lower station, comprising:

• storage means having a storage area;
• extraction means for extracting the types of the repeat data from the received first data stream;
• writing means for writing the extracted repeat data to the storage area;
• detection means for detecting the null data packet in the received second type of data stream;
• output data selection means for successively selecting one of the types of repeat data to be output;
• and
• output means for,
• (c) when the detection means detects the null data packet, reading from the storage means a repeat data packet that composes the selected type of repeat data, replacing the detected null data packet with the read data packet, and outputting the resulting data stream, and
• (d) when the detection means does not detect a null data packet, outputting the received second data stream.

A data transfer apparatus that receives from an upper station a data stream that includes pieces of repeat data that are repeatedly transmitted by the upper station, and transfers the received repeat data to a lower station, comprising:

• storage means having a storage area for storing one piece of the repeat data;
• extraction means for successively extracting the pieces of repeat data at a time from the received data stream;
• writing means for writing the extracted piece of repeat data to the storage area, and, each time the extraction means newly extracts one of the pieces of repeat data, overwriting the piece of repeat data stored in the storage area with the newly-extracted piece of repeat data;
• and
• output means for reading the piece of repeat data stored in the storage means, and outputting the read piece of repeat data.

A data transfer apparatus that receives from an upper station a data stream that includes pieces of repeat data that are repeatedly transmitted by the upper station, and transfers the received repeat data to a lower station, each piece of repeat data being updated at a predetermined interval and including update information showing that the updated piece of repeat data has been updated, comprising:

• storage means having a storage area for storing one piece of the repeat data;
• extraction means for successively extracting the pieces of repeat data from the received data stream;
• update judgement means for judging, based on the update information, whether the extracted piece of repeat data has been updated;
• writing means for writing a first extracted piece of repeat data to the storage area, and, only when one of the extracted pieces of repeat data is judged to have been updated, replacing the updated piece of repeat data with the piece of repeat data stored in the storage means;
• and
• output means for reading the piece of repeat data stored in the storage means, and outputting the read piece of repeat data.

A data transfer method used in a data transfer apparatus that (a) receives from an upper station a data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station, (b) transfers the repeat data to a lower station, and (c) has a storage area, the method comprising:

• an extraction step for extracting the types of repeat data from the received data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a data structure ratio determination step for determining a ratio between the types of repeat data to be output in a data stream per fixed length of time;
• and
• a data output step for reading the repeat data stored in the writing step, and outputting the read repeat data at the determined ratio.

A recording medium having a program recorded thereon for use in a data transfer apparatus, the data transfer apparatus . (a) receiving from an upper station a data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station, (b) transferring the repeat data to a lower station, and (c) having a storage area, the program comprising:

• an extraction step for extracting the types of repeat data from the received data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a data structure ratio determination step for determining a ratio between the types of repeat data to be output in a data stream per fixed length of time;
• and
• a data output step for reading the repeat data stored in the writing step, and outputting the read repeat data at the determined ratio.

A program for use in a data transfer apparatus that (a) from an upper station a data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station, (b) transfers the repeat data to a lower station, and (c) has a storage area, the program comprising:

• an extraction step for extracting the types of repeat data from the received data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a data structure ratio determination step for determining a ratio between the types of repeat data to be output in a data stream per fixed length of time;
• and
• a data output step for reading the repeat data stored in the writing step, and outputting the read repeat data at the determined ratio.

A data transfer method for use in a data transfer apparatus that (a) receives from an upper station (i) a first type of data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station and being composed of a plurality of repeat data packets, and (ii) a second type of data stream that includes at least one null data packet that is a dummy data packets that does not include data to be reproduced and displayed, (b) transfers the received repeat data to a lower station, and (c) has a storage area, the method comprising:

• an extraction step for extracting the types of the repeat data from the received first data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a detection step for detecting the hull data packet in the received second type of data stream;
• an output data selection step for successively selecting one of the types of repeat data to be output;
• and
• an output step for,
• (d) when the detection step detects the null data packet, reading from the storage area a repeat data packet that composes the selected type of repeat data, replacing the detected null data packet with the read data packet, and outputting the resulting data stream, and
• (e) when the detection step does not detect a null data packet, outputting the received second data stream.

A recording medium having a program recorded thereon for use in a data transfer apparatus that (a) receives from an upper station (i) a first type of data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station and being composed of a plurality of repeat data packets, and (ii) a second type of data stream that includes at least one null data packet that is a dummy data packets that does not include data to be reproduced and displayed, (b) transfers the received repeat data to a lower station, and (c) has a storage area, the program comprising:

• an extraction step for extracting the types of the repeat data from the received first data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a detection step for detecting the null data packet in the received second type of data stream;
• an output data selection step for successively selecting one of the types of repeat data to be output;
• and
• an output step for,
• (d) when the detection step detects the null data packet, reading from the storage area a repeat data packet that composes the selected type of repeat data, replacing the detected null data packet with the read data packet, and outputting the resulting data stream, and
• (e) when the detection step does not detect a null data packet, outputting the received second data stream.

A program for use in a data transfer apparatus that (a) receives from an upper station (i) a first type of data stream that includes a plurality of types of repeat data, each type of repeat data being repeatedly transmitted by the upper station and being composed of a plurality of repeat data packets, and (ii) a second type of data stream that includes at least one null data packet that is a dummy data packet that does not include data to be reproduced and displayed, (b) transfers the received repeat data to a lower station, and (c) has a storage area, the program comprising:

• an extraction step for extracting the types of the repeat data from the received first data stream;
• a writing step for writing the extracted repeat data to the storage area;
• a detection step for detecting the null data packet in the received second type of data stream;
• an output data selection step for successively selecting one of the types of repeat data to be output;
• and
• an output step for,
• (d) when the detection step detects the null data packet, reading from the storage area a repeat data packet that composes the selected type of repeat data, replacing the detected null data packet with the read data packet, and outputting the resulting data stream, and
• (e) when the detection step does not detect a null data packet, outputting the received second data stream.