JP2001103093A - Method and device for transmitting data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve problems that free time in which data do not flow on a transmission medium is generated at switching between transmission and reception, and the free time lowers transmission efficiency in a ping-pong transmission system. SOLUTION: By providing information relating to the length of a packet in a header part of a packet and deciding the end time of the packet not at the last of the packet but at the head of the packet, unoccupied time of the transmission medium is reduced and the transmission efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission method and apparatus for performing ping-pong transmission on a single transmission medium.

[0002]

2. Description of the Related Art (One-way bidirectional technology) As a method for realizing bidirectional transmission on one transmission medium, a time-division multiplexing system in which the direction of transmission is switched by time division, a frequency which varies depending on the direction of transmission, and the like. There is a method such as a frequency multiplexing method for switching the signal.

(Time-Division Multiplexing) A main method of bidirectional transmission using the time-division multiplexing method is a ping-pong transmission method (official name: time-division directional control transmission method) used for ISDN and the like. In this method, bidirectional communication is realized by repeating transmission and reception of a data amount determined at a fixed ping-pong cycle. At this time, a signal sequence transmitted at one time is called one burst.

(Variable Burst Length) In general data transmission, normal data is transmitted in packets each having a length of several tens of characters or more in a character unit, which is a set of a fixed number of bits. A control code for controlling a bus or the like often requires only a few characters (one character in some cases).

However, in the above ping-pong system, the time of one burst is half fixed, so that all packets have a fixed length, which is inefficient. Therefore, a half-duplex system in which packets of different lengths are transmitted for each burst has been considered.

(Switching between transmission and reception) In the ping-pong method, since one transmission medium is used for both transmission and reception, it is necessary for the transmission / reception device to switch between transmission and reception.

(Conventional example) An example of a conventional method / apparatus for performing transmission / reception of a ping-pong transmission system will be described with reference to FIGS.

In this example, a code having a certain number of bits is collectively processed into one character, and two types of transmission codes, a control code and a data code, are transmitted. The control code is transmitted as a fixed-length packet having a code part of three characters, the data code is transmitted as a variable-length packet, and a data end code is added with a data end code at the end. The control code is a three-character code, but as long as it has a fixed length,
Any number of one or more characters may be used.

FIG. 11 shows the structure of a packet in this case. FIG. 11A shows a control code packet, and FIG. 11B shows a data code packet. All packets have a configuration of [header] + [code].

The control code packet has a configuration of [header] + [control code], and is a control code 51 for controlling the ping-pong transmitting / receiving apparatus and the network, and for notifying the state of the apparatus to the network and the partner device.
e is a packet for transmitting e.

Reference numeral 50e denotes a header portion of the packet, which is used for synchronizing characters on the receiving side. Here, the length of the header is one character, but any length may be used. 51e is a control code. The code must be such that the end of the packet can be determined by reading the last character of the control code. For example, if the control code has a plurality of character lengths, the last character may be a data end code.

A data code packet is a packet for transmitting a data code, and has a configuration of [header] + [data code] + [data end code].

Reference numeral 52 denotes a data code. The length is variable and may be appropriately coded. 53
Is a data end code indicating the end of data.

FIG. 9 is a block diagram of an apparatus for transmitting data by the method of this embodiment. 1e and 1f are data transmission devices. The internal configuration is the same for both, and details of the interior will be described later. Reference numeral 2 denotes a transmission path for performing data transmission. The transmission path may be a transmission medium such as an electric wire, an optical fiber, a radio, and an infrared ray.

Reference numeral 10 denotes a transmission / reception unit, which transmits a transmission packet 28 output from the transmission packet generation unit 15e to the partner device via the transmission line 2, and receives a reception packet 21 sent from the partner device via the transmission line 2. Output to the bit synchronization unit 11.

The transmitting / receiving unit 10 has a function of converting the transmission packet 28 and the reception packet according to the transmission path 2. That is, for example, when the transmission path is an optical fiber, it includes a function of performing conversion between an electric signal and an optical signal, and performing modulation / demodulation. The same applies when the transmission path 2 is another transmission medium.

Reference numeral 21 denotes a received packet.
And is input to the bit synchronization unit 11. Reference numeral 11 denotes a bit synchronization unit which synchronizes the signal 21 output from the transmission / reception unit 10 with an internal clock on a bit-by-bit basis.
2 to the character synchronizing unit 12. Reference numeral 22 denotes a signal after bit synchronization, which is output from the bit synchronization unit 11 and input to the character synchronization unit 12.

Reference numeral 12 denotes a character synchronizing unit which outputs the post-bit synchronizing signal 22 to the reception data buffer 13 and the transmission / reception control unit 14e through a clock 24 in synchronization with an internal character clock. Reference numeral 24 denotes a signal after character synchronization, which is output from the character synchronization unit 12 and is input to the reception data buffer 13, the code determination unit 17 and the reception end determination unit 18e in the transmission / reception control unit 14e.

Reference numeral 13 denotes a reception data buffer, which stores the received signal 24 output from the character synchronization section 12. An output from the reception data buffer 13 is input to a location (not shown) (not shown) using data exchanged by ping-pong transmission.

The transmission / reception control unit 14e includes a code determination unit 17
And a reception end determination unit 18e. 17 is a code determination unit. The control code to be transmitted is determined according to the state of the transmitting / receiving device or the location where data is used, and the code is
To the transmission packet generation unit 15e through. Also,
It determines whether to transmit data or a control code, and notifies the transmission packet generation unit 15e of the result.

Reference numeral 18e denotes a reception termination determining unit. Signal 24
, The reception start signal 25 is output to the transmission packet generation unit 15e. When the received signal is the data end code or the last character of the control code, it is determined that the reception is completed.

Reference numeral 25 denotes a transmission start signal, which is output from the reception end determination section 18e and input to the transmission packet generation section 15e. Reference numeral 26 denotes a control code to be transmitted, which is generated by the code determination unit 17 based on the state of a device such as a transceiver, and is input to the transmission packet generation unit 15e.

Reference numeral 15e denotes a transmission packet generation unit. When a transmission start signal 25 output from the reception end determination unit 18e is input, when transmitting a control code, a header is added to the control code 26 to be transmitted. A transmission packet 28 is generated and output to the transmission / reception unit 10. When transmitting a data code, a transmission packet 28 in which a header is added before the transmission data 27 and a data end code is added later to the transmission / reception unit 10
Output to

A transmission data buffer 16 outputs data 27 to be transmitted to the transmission packet generator 15e. The transmission data buffer 16 is input from a location (not shown) (such as an upper layer) using data exchanged by ping-pong transmission. Reference numeral 27 denotes data to be transmitted, which is output from the transmission data buffer 16 and input to the transmission packet generator 15e.

Reference numeral 28 denotes a transmission packet, which is output from the transmission packet generation unit 15 e and input to the transmission / reception unit 10.

FIG. 10 shows the timing at which each signal is output at this time. Reference numeral 30 denotes a timing at which the transmission / reception unit 10 outputs the reception packet 21. 31
Is the timing at which the bit synchronization unit 11 outputs the post-bit synchronization signal 22. 33 is a character synchronization unit 1
2 is the timing at which the post-character synchronization signal 24 is output. Reference numeral 37 denotes a timing at which the transmission start signal 25 is output from the reception end determination unit 18e. Reference numeral 34 denotes a timing at which the data 27 transmitted from the transmission data buffer 16 or the control code 26 transmitted from the code determination unit 17 is read. Reference numeral 35 denotes a timing at which the transmission packet 28 to which the header is added is output from the transmission packet generation unit 15e.

Reference numeral 40e denotes a period during which no signal is input to the transmission / reception unit 10, that is, a period during which the transmission line 2 is not used for transmission or reception.

[0028]

In the ping-pong transmission method, since one transmission medium is used for both transmission and reception, each transmission device transmits the transmission medium to the transmission path and the reception path at a certain timing. Transmission is performed by switching, but during this switching between transmission and reception, idle time occurs in the transmission medium.

An object of the present invention is to reduce the time required for switching between transmission and reception, thereby reducing idle time during which data does not flow on a transmission medium, and improving transmission efficiency.

[0030]

According to the present invention, in order to solve the above-mentioned problems, information on the length of the packet is provided in the header of the packet so that the end of the packet is not at the end of the packet but at the beginning of the packet. By judging,
Quickly switch from reception to transmission to shorten the ping-pong response time. Specifically, based on the data transmission method described below, the above-described problem is solved by using the data transmission device described below.

A data transmission method according to the present invention is a data transmission method for transmitting a packet including at least a header and a code body in a bidirectional manner in a time-division manner. Contains information on whether the packet has a specific length (fixed length) or other length (variable length). Upon reception, the header is analyzed to determine whether the packet length is the specific length. It is characterized in that transmission is started after elapse of a predetermined time set corresponding to the length of a fixed-length packet if the length is determined to be a length other than the specified length. .

On the transmitting side, different headers are added to the fixed length packet and the variable length packet, and on the receiving side, the header is analyzed to determine whether the packet is fixed length or variable length. , The time from the reception of the header is counted by a timer, and transmission is started when a predetermined time determined by the length of the fixed-length packet has elapsed.

Thus, when a packet containing information indicating that the header has a fixed length is received, the reception end time can be known without waiting for the end of the packet. Switching from reception to transmission can be performed faster than when switching from transmission to transmission.

A data transmission method according to the present invention is a data transmission method for transmitting a packet including at least a header and a code body bidirectionally in a time-division manner. At the time of reception, the header is analyzed to detect information indicating the length of the packet. Based on the information of the detected length, the time required until the end of reception is calculated. The transmission is started after a lapse of time.

On the transmitting side, a header containing the length of the packet as information is added, and on the receiving side, the length of the packet is detected from the header of the packet, and a timer is set to a waiting time determined by the length. Then, the time from the reception of the header is counted by a timer, and the transmission is started when the above waiting time has elapsed.

Thus, when a packet containing the packet length information in the header is received, the reception end time can be known without waiting for the end of the packet. Switching from reception to transmission can be performed faster than in the case of switching to.

The data transmission method according to the present invention is a data transmission method for transmitting a fixed-length packet bidirectionally in a time-division manner. The transmission is started after a lapse of a predetermined time.

More specifically, the receiving side counts the time from when the head of the packet is received by a timer, and starts transmission when a predetermined time determined by the length of the packet has elapsed.

[0039] Thereby, the reception end time can be known without waiting for the end of the packet, so that the switching from reception to transmission can be performed earlier than in the case where the reception is switched to transmission after receiving until the end of the packet. .

A data transmission device according to the present invention is a data transmission device for performing data transmission based on the data transmission method of the present invention, and analyzes a header of a received packet,
A function to determine whether the packet length is a certain length (fixed length) or another length (variable length), and if it is determined to be the above specific length, it corresponds to the packet length And a function of starting transmission after a predetermined time elapses.

The data transmission apparatus according to the present invention is the above data transmission apparatus, and has a function of adding different headers when a transmission packet has a specific length and when the transmission packet has a length other than the specific length. It is characterized by having.

A data transmission device according to the present invention is a data transmission device for performing data transmission based on the data transmission method of the present invention, and analyzes a header of a received packet,
At least a function of detecting information indicating the length of a packet, and a function of calculating a time required to complete reception based on the information of the detected length and a function of starting transmission after the required time has elapsed. It is characterized by having.

[0043]

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS.

In this example, it is assumed that a control code is transmitted as a fixed-length packet having a code length of 3 characters and a data code is transmitted as a variable-length packet, and a data end code is added at the end of the variable-length packet. .

In this example, the control code is a three-character code, but any number of one or more characters may be used as long as it has a fixed length.

FIG. 3 shows the configuration of the packet in this case. FIG. 3A shows a control code packet, and FIG. 3B shows a data code packet.

The control code packet has a structure of [header for fixed-length packet] + [control code], and is a control code for controlling the ping-pong transmitting / receiving apparatus and the network and for notifying the state of the apparatus to the network. This is a packet for transmitting 51a. 50a1 is a header for a fixed-length packet, which is used for synchronizing characters and determining that the packet has a fixed length.

The data packet is a packet for transmitting data itself, and has a configuration of [variable length packet header] + [data code] + [data end code]. 50a2 is a header for a variable length packet. 5
2 is a data code. The length is variable and may be appropriately coded. 53 is a data end code.

The codes 50a1 and 50a2 may be completely different codes, or may have a format in which a part of the header has bits for indicating a fixed length or a variable length. In this example, the length of the header is one character, but may be any length, and the length of the fixed-length packet header 50a1 and the length of the variable-length packet header 50a2 may be different.

Next, FIG. 1 shows a block diagram of an apparatus for performing transmission and reception by this method. Hereinafter, only different points from FIG. 9 will be described. 1a and 1b are data transmission devices.
The internal configuration is the same for both, and details of the interior will be described later.

The bit synchronizer 11 synchronizes the bit of the received signal, and the character synchronizer 12 and the header analyzer 20
The signal 22 after the bit synchronization is output to a.

The character synchronizing section 12 synchronizes the characters of the received signal, and outputs a post-character synchronizing signal 24 to the reception data buffer 13, the code judgment section 17, and the reception end judgment section 18a.

The transmission / reception control unit 14a includes the code determination unit 1
7. It comprises a reception end determining unit 18a, a header analyzing unit 20a and a fixed timer 19a.

The reception end judgment by the reception end judgment section 18a is made based on whether or not a data end code has been received. When the data end code is detected from the post-character synchronization signal 24, the transmission start signal 25 is output.

Since the determination of the end of the reception of the fixed-length packet is performed using the header analysis unit 20a and the fixed-length timer 19a, only the end of the reception of the variable-length packet is determined here. Therefore, when the received packet has a fixed length, the transmission start signal 25 is not output. if,
If it is difficult or not desirable not to output the transmission start signal 25 when a fixed length packet is received, the transmission packet generation unit 15a receiving this signal receives the fixed length packet. The transmission start signal 25 at this time may be ignored.

Reference numeral 20a denotes a header analysis unit which reads a header from the input signal 22 and judges whether the packet is of fixed length or variable length. If the packet is of fixed length, a timer start signal 29a is output to the fixed length timer. 19a.

The fixed-length timer 19a starts the timer when the timer start signal 29a is input, and outputs the transmission start signal 23 to the transmission packet generator 15a when the timer value reaches a predetermined fixed value.

When the transmission start signal is input from 25 or 23, the transmission packet generation unit 15a uses a header for a fixed length packet when transmitting a control code, and a header for a variable length packet when transmitting data. Is added before the control code or the data code, and when transmitting data, a data end code is added at the end of the data code to generate and output the transmission packet 28.

FIG. 4 shows a flowchart of the processing on the receiving side from when the packet is received until the transmission start signal is output. The description of each step is shown below.

In step S11, information on whether the packet has a fixed length or a variable length is read from the header of the received packet. In S12, it is determined from the information read in S11 whether the received packet is fixed length or variable length, and accordingly, the process proceeds to S13 if fixed length or S15 if variable length.

S13 is a waiting time for outputting the transmission start signal 23 at a timing such that a transmission packet can be sent to the transmission / reception unit 10 immediately after the fixed-length reception packet has passed through the transmission / reception unit 10. Is the time during which the fixed-length timer 19a is operating. The waiting time remaining in S13 is determined by the length of the fixed-length packet and the time required for processing of each unit of the transmission / reception device. In S14, a transmission start signal 23 is output.

Steps S15, S16 and S17 are processing when the received packet is a variable length packet. In this case, since the length of the packet is not known, the process waits for the data end code as in the conventional case. S15 is a step of reading the signal after character synchronization one character at a time. S16 is S
It is determined whether or not the code read in step 15 is a data end code.
The process proceeds to S17, and otherwise returns to S15 to read another character. S17 is a step of outputting the transmission start signal 25.

FIG. 2 shows the timing at which each signal is output when a control code packet is received in this embodiment. The timing when a data packet is received is exactly the same as the conventional example shown in FIG.

Reference numeral 30 denotes the received packet 2
This is the timing at which 1 is output. Reference numeral 31 denotes a timing at which the bit synchronization unit 11 outputs the post-bit synchronization signal 22. Reference numeral 38 denotes a timing at which the timer start signal 29a is output from the header analysis unit 20a. 32
Is the timing at which the transmission start signal 23 is output from the fixed length timer 19a. 33 is a character synchronization unit 12
Is the timing at which the post-character synchronization signal 24 is output from the. Reference numeral 34 denotes a timing at which the transmission data 27 is read from the transmission data buffer 16. Reference numeral 35 denotes a timing at which the transmission packet 28 to which the header is added is output from the transmission packet generation unit 15a.

Reference numeral 40a denotes a period during which no signal is input to the transmission / reception unit 10 when this method is used, that is, a period during which the transmission line 2 is not used for transmission or reception. 4
1a is a time during which the fixed length timer 19a is operating.

The above block diagram and timing diagram are merely examples, and the timing at which the transmission start signal and the timer start signal are output greatly depends on the mounting method and the characteristics of the protocol. For example, when the length of the fixed-length code portion is one character, the idle time of the transmission line 2 cannot be sufficiently reduced unless transmission is performed simultaneously with the detection of the header. It is necessary to make a change such that a transmission start signal is issued as soon as the data is read. Further, the timer function can be provided to other parts (for example, the transmission packet generation unit 15a and the header analysis unit 20a).

In this example, the header is read immediately after the bit synchronization. However, if the timing permits, the header can be read after the character synchronization.

In this example, the transmission data is input to the transmission data buffer 16 from an upper layer or the like, and a header is added to the data by the transmission packet generator 15a. Both may be input to the transmission data buffer 16 in the form of being added.

The above description has been made on the assumption that a header indicating this is added to all fixed-length packets. In other words, the receiving side performs the same processing as a variable-length packet.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIGS. This example is a data transmission in which all packets are of variable length.

The packet format in this case is shown in FIG.
(A). The packet has a configuration of [header] + [code], and there is no difference between the control code and the data code.

Reference numeral 50c denotes a packet header which is used for synchronizing characters on the receiving side and for describing the length of the packet. The header here is one character long, but may be longer if necessary. The header 50c includes a portion 60 for describing packet length information. 52c is a code portion to be transmitted.

Next, FIG. 5 shows a block diagram of an apparatus for transmitting and receiving by this method. Hereinafter, only different points from FIG. 1 will be described. 1c and 1d are data transmission devices.
The internal configuration is the same for both, and details of the interior will be described later.

Reference numeral 14c denotes a transmission / reception control unit for performing communication by this method, which includes a code determination unit 18, a variable length timer 19
c, a header analysis unit 20c.

Reference numeral 20c denotes a header analysis unit which reads length information from the header of the post-bit synchronization signal 22, and outputs length information 29c to the variable length timer 19c.

Reference numeral 19c denotes a variable length timer, and length information 2
When 9c is input, the timer limit is set according to the length information and the timer is started. When the value of the timer reaches the set limit value, the transmission start signal 23 is output to the transmission packet generation unit 15c.

Reference numeral 15c denotes a transmission packet generation unit which, when a transmission start signal is input from 23, reads out transmission data and its code length 27 from the transmission buffer 16 and replaces the data string length with a transmission header. Transmission packet 28
Is output to the transmission / reception unit 10.

FIG. 8 shows a flowchart of the processing on the receiving side from when the packet is received until the transmission start signal is output. The description of each step is shown below.

At S21, length information contained in the header of the received packet is read. In S22, according to the length information read in S21, a waiting time for outputting the transmission start signal 23 at a timing such that the transmission packet can be transmitted to the transmission / reception unit 10 immediately after the reception packet passes through the transmission / reception unit 10. Is set to the timer. The waiting time can be easily calculated from the length of the packet (read in S21) and the time required for processing of each unit of the transmitting / receiving device (unique for each device).

At S23, it is determined whether the timer has reached the specified time set at S22. If not reached, the process proceeds to S24, and if reached, the process proceeds to S25. In S24, the timer is advanced by one for one clock. In S25, since the waiting time has ended, the transmission start signal 23 is output.

FIG. 6 shows the timing at which each signal is output when a control code packet is received in this embodiment.

Reference numeral 30 denotes a received packet 2
This is the timing at which 1 is output. Reference numeral 31 denotes a timing at which the bit synchronization unit 11 outputs the post-bit synchronization signal 22. Reference numeral 36 denotes a timing at which the length information 29 of the received header is output from the header analysis unit 20c. 32
Is the timing at which the transmission start signal 23 is output from the variable length timer 19c. 33 is a character synchronization unit 12
Is the timing at which the post-character synchronization signal 24 is output from the. Reference numeral 34 denotes a timing at which the transmission data 27 is read from the transmission data buffer 16. Reference numeral 35 denotes a timing at which the transmission packet 28 is output from the transmission packet generation unit 15c.

Reference numeral 40c denotes a period during which no signal is input to the transmission / reception unit 10 when this method is used, that is, a period during which the transmission line 2 is not used for transmission or reception.

Reference numeral 41c denotes a time during which the variable length timer 19c is operating, and varies depending on the length of the received packet.

In this example, for all packets,
Although the length of the data portion is described in the header portion of the packet, even when the length of the data portion is described only for some of the packets, as in the first embodiment, The method of the present invention can be applied in a method of optimizing the transmission timing only when a packet whose length is known is received. In that case, for example,
In the header part, "the length is not known" is described, and in the packet in which the length information is not described, FIG.
As shown in (b), a data end code is added to the end of the data. On the receiving side, similarly to FIG. 1, a reception end determination unit in parallel with the code determination unit is added, and when a “unknown length” packet is received, similar to the variable length packet of the first embodiment (ie, (Similar to the conventional method).

(Embodiment 3) A third embodiment of the present invention will be described. In this example, the lengths of packets to be transmitted are all the same.

In this case, the packet header (or
After receiving the first bit or character)
A transmission start signal may be output after a predetermined time.

The processing is almost the same as that of the first embodiment when a fixed-length packet is received, except that there is no need to analyze the header.

The transmitting / receiving device in this case is the one shown in FIG.
a, the reception end determination unit 18a is removed, and the header analysis unit 20 is replaced by a header detection unit having a function of detecting at least the header of a packet or the beginning of a packet.

[0090]

By comparing the timing charts of FIGS. 2 and 6 with those of FIG. 10, the timing at which the reception ends when the header is read can be understood.
It can be seen that transmission can be started earlier. Because of this,
Times 40a and 40c when nothing is input to the transmission / reception unit (that is, time when nothing flows on the transmission medium) are shorter than those of the conventional 40e.

As described above, even if the packet is not completely received, the start of transmission can be hastened by knowing the length of the received data when the header portion of the packet is received. . As a result, the idle time of the transmission medium can be reduced, and the transmission efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram of a data transmission device according to a first embodiment of the present invention.

FIG. 2 is a timing chart of a data transmission method according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a packet configuration according to the first embodiment of the present invention;

FIG. 4 is a processing flowchart at the time of reception according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a data transmission device according to a second embodiment of the present invention.

FIG. 6 is a timing chart of a data transmission method according to the second embodiment of the present invention.

FIG. 7 is a diagram illustrating a packet configuration according to the second embodiment of the present invention;

FIG. 8 is a processing flowchart at the time of reception according to the second embodiment of the present invention.

FIG. 9 is a block diagram of a data transmission device in ping-pong transmission according to a conventional method.

FIG. 10 is a timing diagram of ping-pong transmission in a conventional method.

FIG. 11 is a diagram illustrating a packet configuration in a conventional ping-pong transmission method.

[Explanation of symbols]

1a, 1b Data transmission device 1c, 1d according to Embodiment 1 of the present invention Data transmission device 1e, 1f according to Embodiment 2 of the present invention Data transmission device according to conventional example 2 Transmission medium for performing ping-pong transmission 10 Transmitter / receiver 11 Bit synchronization unit 12 Character synchronization unit 13 Receive data buffer 14a Transmission / reception control unit 14c of data transmission device according to Embodiment 1 of the present invention 14c Transmission / reception control unit of data transmission device according to Embodiment 2 of the present invention 14e Data transmission device according to conventional example Transmission / reception control unit 15a of transmission packet generation unit of data transmission device according to Embodiment 1 of the present invention 15c Transmission packet generation unit of data transmission device according to Embodiment 2 of the present invention 15e Transmission packet generation unit of data transmission device in conventional example 16 transmission data buffer 17 code judgment unit 18a Receiving end determining unit of data transmission device according to Embodiment 1 of the present invention 18e Receiving end determining unit of data transmitting device in conventional example 19a Fixed length timer unit of data transmitting device according to Embodiment 1 of the present invention 19c Variable length timer section 20a of data transmission apparatus in the second embodiment 20a Header analysis section of data transmission apparatus in the first embodiment of the present invention 20c Header analysis section of data transmission apparatus in the second embodiment of the present invention 21 bits are synchronized No received packet 22 Bit synchronization signal 23 Transmission start signal determined by timer 24 Character synchronization signal 25 Transmission start signal determined by reception end determination unit 26 Control code to be transmitted 27 Read transmission data 28 Transmission packet 29a Timer start signal 29c Packet length detected from header Information 30 Timing at which the received packet before bit synchronization is output 31 Timing at which the signal after bit synchronization is output 32 Timing at which the transmission start signal is output from the timer 33 Timing at which the signal after character synchronization is output 34 Transmission from the transmission buffer The timing at which the data or the transmission control code is read from the transmission / reception control unit 35 The timing at which the transmission packet is output 36 The timing at which the header length information of the reception packet is output 37 The data end code or the last character of the control code is received The timing at which the transmission start signal is output 38 The timing at which the timer start signal is output 40a The idle time of the transmission medium according to Embodiment 1 of the present invention 40c The idle time of the transmission medium according to Embodiment 2 of the present invention 40e Conventional example In The idle time 41a of the fixed-length timer in the first embodiment of the present invention 41a The variable-length timer operating time 50a1 in the second embodiment of the present invention Header 50a2 attached to variable-length packet according to the first embodiment of the present invention 50c Header 50e including packet length information according to the second embodiment of the present invention Header 51a attached to a packet in the conventional example 51a of the present invention Control code 51e in Embodiment 1 Control code 52 in the conventional example 52 Data code to be transmitted 52c Code to be transmitted 53 Data end code 60 Packet length information in header

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masafumi Takahashi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Yuji Ichikawa 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Kazuki Sumimi 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (72) Inventor Toru 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation F Terms (reference) 5K030 GA03 HA08 HB29 JA05 KA03 LD18 MB11 5K034 EE05 EE11 HH01 HH02 HH06 HH21 HH65 MM05

Claims (7)

[Claims] 1. A data transmission method for transmitting a packet including at least a header and a code body bidirectionally in a time-division manner, wherein a header of at least a part of the packet has a packet length having a specific length (fixed length). ) Or other length (variable length), and upon reception, analyze the header to determine whether the packet length is the specific length or other length. A data transmission method for starting transmission after a lapse of a predetermined period of time determined according to the length of the fixed-length packet when the transmission is determined to be the specific length. 2. A data transmission method for bidirectionally transmitting a packet including at least a header and a code body in a time-division manner, wherein at least a part of the packet includes information indicating the length of the packet. Sometimes, the header is analyzed to detect information indicating the length of the packet, and the time required to complete reception is calculated based on the information on the detected length of the packet, and transmitted after the required time has elapsed. A data transmission method, characterized by starting the process. 3. A data transmission method for transmitting a fixed-length packet bidirectionally in a time-division manner, wherein after a head of the packet has been received, a predetermined period of time determined according to the length of the fixed-length packet has elapsed. A data transmission method characterized by starting transmission later. 4. A data transmission apparatus for performing data transmission by the method according to claim 1, wherein a header of a received packet is analyzed to determine whether the packet length is a specific length (fixed length). Other length (variable length)
And a function of starting transmission after a lapse of a predetermined period of time determined in accordance with the length of the fixed-length packet when determined to be the specific length. A data transmission device characterized by the above-mentioned. 5. The data transmission device according to claim 4, wherein the transmission packet has a specific length (fixed length);
A data transmission device having a function of adding a different header when the length is other than that (variable length). 6. A data transmission apparatus for performing data transmission by the method according to claim 2, comprising: a function of analyzing a header of a received packet to detect at least information indicating a length of the packet; A data transmission device, comprising: a function of calculating a required time until the end of reception based on information on a detected packet length; and a function of starting transmission after the required time has elapsed. 7. A data transmission apparatus for performing data transmission by the method according to claim 3, wherein after receiving a head of a received packet, the data transmission apparatus determines a fixed length corresponding to a length of a fixed-length packet. A data transmission device having a function of starting transmission after a lapse of time.