JPH07193614A - Data transmission method - Google Patents

Abstract

PURPOSE:To efficiently attain data transmission without deterioration in the accuracy by presetting a frame length to a subtraction counter in response to a frame length code in transmission data in a predetermined format and checking a data error after the end of reception. CONSTITUTION:Transmission data from a data carrier of a mobile body 12 are made up of command data including a code representing a frame length in succession to a header, data, and a frame check code or the like at the end of the transmission data. The transmission data are received by an antenna 13, the frame length is preset to a counter based on the frame length code, and the counter is decremented by each reception of 1-byte data. When the count reaches 0, an error is checked based on the frame check code and an and response is sent. the succeeding data are sent with a high efficiency by the system using the format above without deterioration in accuracy because no timer is required.

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 when data is updated between a transmission side and a reception side, and particularly, data transmission is performed in a non-contact manner, and one side does not have a built-in battery and the other side does not. The present invention relates to a data transmission method, which is preferably applied to a non-contact data communication device that charges a received signal of a signal transmitted from a device to supply power to a circuit.

[0002]

2. Description of the Related Art Generally, when transmitting data from a transmitting side to a receiving side, a checksum code or a CRC check code is added to the end of a transmission data frame. The receiving side checks the transmission data frame based on this code.

Further, recently, a device which is arranged on a conveyor line or the like in a factory and performs data communication between a tag attached to an article passing on the conveyor and an antenna portion arranged so as to face the tag. However, in such a device, since the tag and the antenna are very close to each other, a battery is not built in the tag side, and the tag is charged by charging the capacitor with the transmission power from the antenna side. There is one that supplies power to the circuit (Japanese Patent Laid-Open No. 62-39927). Further, in the non-contact type data communication device disclosed in the publication, in addition to securing the power source on the tag side by charging the capacitor with electromagnetic waves transmitted from the antenna side, transmission / reception timing on the antenna side and tag side A timer is used to control the. That is, the antenna side (first antenna coil)
Simultaneously with the start of the data transmission from (1), the tag side (reception side) starts counting the timer, and after counting a certain period of time, it returns. Further, the time allotted to the reply (transmission from the second antenna coil) is fixed by the counting time of the timer. That is, the communication time of transmission and reception is controlled by the timer regardless of the transmission frame length.

[0004]

As described above, since the frame check code set at the last position of the transmission data frame is checked by the receiving side, the receiving side receives the frame check code from the received data. Need to be extracted. In this case, if the transmission data frame is continuously sent to the end without interruption, the data of the last part of the reception data string can be judged as the frame check code, so this data part is extracted and checked. However, if the transmission data frame may be transmitted intermittently, the receiving side cannot judge the data of the last part of the reception data string of the group once received as the frame check code.
In such a case, for example, when the reception of a group of transmission data has been completed and no reception has been made for a certain period of time, it is determined that all the data has been received, and the last portion of the reception data sequence at that time is framed. It is necessary to devise a method to extract it as a check code.

Further, as shown in the above-mentioned Japanese Patent Laid-Open No. 62-39927, the battery is not built in the tag side,
While securing the power supply to the circuit inside the tag by using the transmission power from the antenna side, in the method of controlling the transmission and reception timing of the antenna side and the tag side by the timer, the transmission data frame transmitted from the antenna side, or Even when the length of the transmission data frame transmitted from the tag side is not constant, that is, even when the length of the transmission data frame is short, the non-transmission time zone is always formed for the transmission / reception timing control by the timer. Therefore, that time becomes a wasteful standby time, and particularly when the antenna side and the tag side repeatedly perform transmission / reception, this wasteful standby time is accumulated, and the communication efficiency becomes extremely low. there were.

Further, when the accuracy of the timer is low, the transmission timings of both sides may be deviated. In such a case, the antenna side and the tag side simultaneously transmit, resulting in a communication failure. There was also a problem that occurred.

An object of the present invention is to provide a data transmission method in which a new transmission data frame such as a response signal can be transmitted to the transmitting side immediately after the reception of the transmission data frame, and the communication efficiency is improved. To do.

Still another object of the present invention is to make it possible to check the transmission frame immediately after receiving the transmission data frame from the transmitting side, facilitating the check of the transmission frame data and reliability of the transmission frame data. Another object of the present invention is to provide a data transmission method that improves the quality.

Still another object of the present invention is to secure the operating power source on the receiving side by the transmission power from the transmitting side, and to perform data communication without monitoring the transmission / reception timing with a timer. It is to provide a transmission method.

[0010]

A data transmission method according to the present invention is characterized in that frame length data indicating a frame length is set at a first position of a transmission data frame. Then, when the frame length data is received on the receiving side, the corresponding value of the frame length data is preset in the counter, the counter is decremented as the data is received thereafter, and the count value counts the preset value. When the transmission is completed, it is determined that all the transmission data frames have been received, and the process proceeds to the next data processing after receiving the transmission data frames. The next data processing after receiving the transmission data frame is the transmission processing of a new transmission data frame such as a response to the transmission side and the transmission data frame check based on the frame check code set at the last position of the transmission data frame. It includes processing (error detection processing).

Further, the power of the reception signal of the transmission data frame sent from the transmission side is charged in the capacitor, and this charging power is supplied to the circuit as a power source, thereby eliminating the need for a battery on the reception side. .

[0012]

By setting the frame length data indicating the frame length at the beginning of the transmission data frame transmitted from the transmitting side, the frame length data can be received first when the receiving side starts receiving. By receiving this frame length data first, it is possible to know at that stage the final position of the transmission data frame, that is, the time when all the reception data have been received. That is, when the frame length data is received, the corresponding value of the frame length data is preset in the counter, and thereafter, the preset value is subtracted as the received data is received, whereby all the received data have been received. It can be determined whether or not the value preset to the count value has finished counting. Therefore, when the transmission data frame is interrupted in the middle, the receiving side can know whether or not the time point is the end of the transmission data frame, and when all the data has been received, the next data processing is surely performed. Will be able to. Then, as the data processing performed immediately after receiving all the transmission data frames, there are processing for transmitting a new transmission data frame such as a response (response signal) to the transmission data frame, and setting at the final position of the transmission data frame. The transmission frame check process (error detection process) based on the established frame check code is included.

Further, by rectifying the received signal of the transmission data frame sent from the transmission side and charging it in the capacitor, the charging power of the capacitor from the time when all the transmission data frames have been received, It is possible to secure power for the control unit that generates a new transmission data frame such as a response to the transmission side and that performs a transmission data check (error detection) process based on the frame check code by the charging power of this capacitor. In this case, the capacitor only needs to have a capacity capable of accumulating the amount of energy required to transmit the maximum length frame of the new transmission data frame including the response to be transmitted to the transmitting side. Further, the length of the transmission data frame transmitted from the transmission side may be at least a time longer than the rising time of the charging waveform of the capacitor (time required until completion of charging). The transmission data check process based on the frame check code can be performed during data reception. By doing so, the capacitor becomes a smoothing capacitor that smoothes and stabilizes the rectified voltage.

[0014]

1 is a block diagram of an apparatus in which a data transmission method according to the present invention is implemented. This device is a conveyor 10
A data carrier (tag) 12 attached to a side surface of a moving body (article) 11 moving above, an antenna 13 arranged in a position closely facing the data carrier 12, and the antenna 13 and the outside of the drawing. And a transmission line 14 for connecting to a host controller (which is composed of a programmable controller or the like).

The antenna 13 has a communication area 15 shown in the figure. When the data carrier 12 moves into the communication area 15, its presence is detected and the data carrier 12 is detected.
Communicate with. Data carrier 12 and antenna 1
The configurations of 3 are as shown in FIG. That is, the data carrier 12 stores the data to be transmitted on the side of the antenna 13 and the memory 12a to which the area for storing the data received from the antenna 13 is allocated and the data to be transmitted to the transmission / reception circuit 12c. A control circuit 12b for controlling sending and receiving data received by the transmission / reception circuit 12c and storing it in the memory 12a, a transmission / reception circuit 12c for communicating with the transmission / reception circuit on the antenna side by electromagnetic coupling, and these elements Power supply 12d for supplying power. As will be described later, the power supply 12d includes a capacitor that stores the transmission data frame sent from the antenna side as electric power, and each element is driven by the charging power of this capacitor.

The antenna 13 is connected to the transmission / reception circuit 13c for performing communication by electromagnetically coupling with the transmission / reception circuit 12c of the data carrier 12, and is connected to the transmission / reception circuit 13c to control data transmission or reception and to communicate with the host side. A control circuit 13b for performing control for exchanging data with each other, an interface 13a connected to the transmission line 14 for performing an interface for exchanging data with the host side, and a power supply for these elements. It is composed of a power supply 13d for supplying a voltage.

FIG. 3 shows a detailed block diagram of the data carrier 12. The transmitter / receiver circuit 12c includes a coil L for electromagnetic coupling.
2 and capacitor C1 and coil L1 on the antenna side
It is possible to perform data communication by resonantly coupling with a transmission / reception circuit including. The power supply 12d includes a diode D1, a capacitor C2 and a constant voltage circuit 12f.
It consists of Diode D1 is capacitor C1
The signal current when receiving transmission data from the antenna is rectified by the transmission / reception circuit of the coil L2 and the capacitor C2.
Charges that current. In addition, the constant voltage circuit 12f converts the charging voltage of the capacitor C2 into a constant voltage to control the control circuit 12f.
b, output to the memory 12a and other circuits as a power supply voltage. The output of the amplifier A that amplifies the received signal is input to the control circuit 12b, and the transmission data is output from the control circuit 12b to the transistor Tr1.
Therefore, the reception data is input to the control circuit 12b from the demodulation circuit A that performs waveform shaping and signal demodulation during reception, and the transmission data is transmitted from the control circuit 12b to the transistor T during transmission.
By being output to r1, the transmission data is modulated by the transistor Tr1 and is output as an electromagnetic wave from the resonant circuit of L2 and C1. The power supply voltage at this time is supplied from the capacitor C2.

FIG. 4 shows a time chart when three data frames having different lengths are transmitted from the antenna 13 to the data carrier 12 of the tag with the above circuit configuration.

As shown in the figure, when a data frame is transmitted from the antenna 13, the received current is transferred to the capacitor C.
When the capacitor C2 is charged to 2, the received data is sent to the control circuit 12b by using the capacitor C2 as a power source, and a response data frame is transmitted to the antenna when all the data frames have been received. In this case, although the lengths of the three data frames are different from each other, the data carrier 12 immediately sends a response when each data frame is completed. In this way, regardless of the length of the data frame, the response can be sent immediately after the reception of the data frame is finished, but the reason is that the frame length data indicating the frame length is set at the beginning position of the data frame. This is because the data carrier 12 side can know the data frame length in advance when receiving the data frame. That is, since the final position of the data frame can be known in advance when the reception of the data frame is started, error detection is immediately performed from the frame check code arranged at the final position of the data frame when the final position is reached. This is because the transmitted data including the response can be immediately transmitted to the antenna 13 side from that time.

FIG. 5 shows the format of the transmission data frame. As shown in the figure, there is a header section first, followed by a command code containing frame length data indicating the length of the data frame, followed by the data body section, and finally the frame check. A code (CRC code or the like) is arranged. The data is sequentially sent from the header part, and the transmission ends when the frame check code is completely transmitted. Therefore, on the data carrier side, the command code, that is, the frame length data, can be acquired immediately after receiving the header, and therefore the last of the frame check code can be obtained regardless of the length of the data body at the stage of receiving the frame length data. You can know the position in advance. That is, on the data carrier side, a response can be sent to the antenna immediately after receiving the frame check code, and error detection by the frame check code can be immediately performed.
The above operation will be described with reference to the flowcharts of FIGS.

FIG. 6 shows the operation of the antenna 13, and FIG. 7 shows the operation of the data carrier 12.

When the antenna 13 side prepares the transmission data for the data carrier side, the data frame shown in FIG. 5 is edited and the transmission processing as command data is performed at n1. It should be noted that the antenna 13 does not transmit the command after detecting whether the data carrier 12 has moved into the communication area 15;
On the other hand, command transmission processing is always performed at regular intervals. It is also possible to dispose a photoelectric sensor on the upstream side of the antenna 13 and start the command transmission process after the arrival of the data carrier is detected by this sensor. Then, if there is a response, that is, if the data carrier 12 moves into the communication area 15 and communication becomes possible, data communication is immediately performed, and a transmission data frame of the response transmitted from the data carrier 12 side is received, At n3, the reception of the response is started.

On the other hand, when the data carrier (tag) 12 side receives the command transmitted from the antenna 13 side, the reception is detected at n20 and the command reception is started. As shown in FIG. 5, the data frame has a header part first, and a command code including frame length data is arranged after that, so that the command code has been received before the data body part is received. The frame length of the transmission data frame currently transmitted can be confirmed at (n22). Then, when this frame length is confirmed, the frame length is preset in the counter provided in the control circuit 12b, and then 1
The counter value is decremented by 1 byte each time the byte data is received (n23). Then, it is determined in n24 whether the counter has reached zero. That is, it is determined here whether all the transmitted data frames have been received. When it is determined that all data frames have been received, it is determined whether or not there is a communication error. This determination is based on error detection by a frame check code such as a CRC code arranged at the last position of the data frame.
If there is a communication error, the process proceeds to n27 and error processing is performed. In this case, the NACK signal may be transmitted to the antenna 13 side so as to perform the retry. If there is no communication error, memory read / write processing corresponding to the command code is performed. That is, if the command code is a write command, the data sent after the command code is written in the memory, and then only the response is sent to the antenna 13 side. If the command is a read command, the response data and the memory are sent. The data read from 12a is transmitted to the antenna 13 side as a response.

By the above operation, the data carrier 12
The (tag) received this frame check code because the reception position of the frame check code was immediately known when the command code located at the beginning of the transmission data frame sent from the antenna 13 was received. Immediately after that, error detection can be performed immediately, and a new transmission data frame of the response can be created and returned.

As shown in FIG. 3, the data carrier 12 (tag) does not include a battery, and the circuit is driven by using the capacitor C2 charged with the power of the reception signal of the transmission data frame transmitted from the antenna 13 as a power source. In addition, this capacitor is used as a power source to supply the transmission power of the response to the antenna 13a, but this capacitor C2 supplies the energy required for the maximum response frame length transmitted by the data carrier to the antenna side. It is sufficient that at least the charge that can be supplied is charged (the power supplied to the control circuit 12b, the memory 12a, etc. is extremely smaller than the transmission power). In FIG. 8, the longest frame length command sent from the antenna 13 is C1, the shortest frame length command is C2, and the longest data frame of the response from the data carrier (tag) 12 is R2. Then, the charging potential of the capacitor C2 changes as shown in the figure. Here, the response R having the longest data frame length in the data carrier 12
_Assuming that the charging potential required to transmit 2 is V _min , the charging potential of the capacitor C2 exceeds V _min when the response R2 having the longest data frame length has been transmitted, as shown in the figure. Any size is fine. If the transmission data frame length from the antenna 13 fluctuates according to the command and the response length also fluctuates according to the command, the data frame length increases because the write data is attached in the case of the write command. In the case of a read command, in order to respond by attaching the read data,
The data frame length of the response at that time becomes long. In such a case, if the command C2 of FIG. 8 is used as the read command, the data frame length of the response R2 for it is considered to be the longest, and therefore the capacitance of the capacitor C2 is changed from the data carrier 12 to the antenna
It may be determined based on the longest read data to be transmitted to No. 3.

Flowchart showing the operation of the antenna 13 Returning to FIG. 6, when a response is returned from the data carrier (tag) 12, the antenna 13 starts receiving the response at n3. Hereinafter, similar to the operation of n22 and below of the data carrier (tag) 12, the data frame length is confirmed at n4, and further processing is performed on the counter to confirm whether or not all the data frames have been received, by the count value of the counter, Immediately after that, error detection is immediately performed, and necessary data is transmitted to the host side.
Then, when the command is further continued, the operation from n1 is performed again.

A constant voltage circuit 12f provided in the power supply 12d of the data carrier (tag) 12 is provided with a capacitor for stabilizing the power supply and the transistor T
By providing the backflow prevention circuit so that the voltage on the primary side of the constant voltage circuit does not drop due to the discharge using r1 as the discharge path, the influence of the voltage fluctuation of the resonant circuit of L2 and C1 affects the secondary side of the constant voltage circuit. Can be prevented.

Further, in the above embodiment, the power supply 12d of the data carrier is constituted by a circuit which does not include a battery, but it may be constituted by a battery depending on the system to which the method of the present invention is applied. When the battery is used, the capacitor C2, the diode D1 and the constant voltage circuit 12f are unnecessary, and the battery is directly connected to this portion. Even if the battery constitutes the power source 12d, there is no waste of time in the transmission / reception timing of the data frame,
It is possible to achieve the effect of the present invention that can realize efficient communication.

[0029]

According to the present invention, since the length of the transmission data frame sent from the transmitting side, that is, the position of the last data portion having the check code, is known at the first reception stage, the transmission data Immediately after receiving all the frames, it is possible to immediately perform response processing such as a response (transmission processing of a new transmission data frame to the transmission side), and error detection can be performed immediately. Therefore, there is no waste of time in transmission / reception timing, and there is an effect that extremely efficient data transmission can be realized. Further, since the conventional timer is not used for the transmission / reception timing, it is possible to prevent the occurrence of a communication failure due to the accuracy of the timer, which has the effect of increasing the reliability of the transmission. . Furthermore, even if the transmission data frame is cut off in the middle and retransmitted after a certain period of time, the position of the frame check code sent last when the first frame is received is known. The error detection is not performed in the frame receiving stage, and the error can be correctly detected in the last frame receiving stage. That is, there is an advantage that the reliability of the transmission data is improved because the error detection by the frame check code is extremely easy and surely performed.

Further, if the method of the present invention is applied to the one in which the charging power of the capacitor charged with the received signal is driven as the power source, it is possible to design the optimization of the charge / discharge energy amount of the capacitor in order to shorten the communication time. It is possible, and there is an advantage that the capacity of the charging capacitor can be reduced.

[Brief description of drawings]

FIG. 1 shows a block diagram of an apparatus to which a data transmission method according to the present invention is applied.

FIG. 2 shows a block diagram of the device shown in FIG.

FIG. 3 shows a more detailed block diagram of a data carrier (tag).

FIG. 4 is a diagram showing a data transmission timing between an antenna and a data carrier (tag) and changes in a charging voltage of a capacitor.

FIG. 5 shows a format of a transmission data frame.

FIG. 6 is a flowchart showing the operation of the antenna.

FIG. 7 is a flowchart showing the operation of the data carrier (tag).

FIG. 8 is a diagram showing changes in the charging voltage of the capacitor C2 with respect to a command having the longest data frame length and a response having the longest data frame length.

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[Procedure amendment]

[Submission date] January 17, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 18, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

Claims (4)

[Claims] 1. A frame length data indicating a frame length is set at a first position of a transmission data frame transmitted from a transmission side, and when the reception side receives the frame length data, a counter value corresponding to the frame length data is counted. When the count value has finished counting the preset value, it is determined that all the transmission data frames have been received, and the transmission data frame is received after the transmission data frame is received. A data transmission method, characterized in that the process proceeds to the next data processing. 2. The data transmission method according to claim 1, wherein the next data processing after the reception of the transmission data frame is a transmission processing of a new transmission data frame to the transmission side. 3. The data transmission method according to claim 1, wherein the next data processing after receiving the transmission data frame is a transmission frame check processing based on a frame check code set at the last position of the transmission data frame. . 4. The data transmission method according to claim 1, wherein a capacitor is charged with electric power of a reception signal of the transmission data frame, and the charging electric power is supplied to a circuit as a power source.