JPH1117661A - Data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve throughput by allowing the transmitter to recognize erroneous data without processing by a CPU of a higher level, so as to relieve the load on the CPU. SOLUTION: Transmission data 51, sent from the transmitter are given to a transmitter side data control section 11, a transmitter side frame check sequence FCS calculation section 12 and a selection section 13. The transmitter side FCS calculation section 12 calculates as FCS 53, based on the transmission data 51. In the case that the transmitter side data control section 11 discriminates it that transmission data have an error, the control section 11 uses an inverted control signal 61 to control an inverter section 14 for providing an output of the inverted FCS. The selection section 13 selects the transmission data 51 or an inverter section output 62 (inverted or noninverted FCS) and transmits the selected data to network 3 as output data 52. On the other hand, a receiver side FCS calculation section 22 extracts the FCS from received data 58 and outputs FCS confirmation data 56 to a receiver side data control section 21. The receiver side data control section 21 outputs an error signal 57 of the received data according to the confirmation data 56.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus and, more particularly, to a data transmission apparatus for transmitting data in a frame format having a check code for checking data errors.

[0002]

2. Description of the Related Art Generally, in a network system for data transmission, the data length is not constant and
A device using a frame format having a check code for checking a data error is known. For example, in Ethernet or the like, a frame check sequence (Frame Check Sequence, FCS) is included in a frame format in order to check for a data error. In the following description, a frame for checking a data error is generally referred to as “FCS” or “error detection code”.

On the transmitting side, such an FCS is:
Cyclic Redundancy Check,
This is obtained by performing a CRC) calculation and the like, and is transmitted as a part of transmission data. On the other hand, on the receiving side, the FCS of the received data is calculated, and by confirming whether the FCS of the received data matches the calculated FCS, it is determined whether or not there is an error in the received data. to decide. If these FCSs do not match, the receiving side determines that the data has a transmission error (transmission error) and discards the data.

[0004] An example of a transmission error will be described below. -Long data (when the size of the data to be transmitted exceeds the value specified by the standard during transmission)-Incomplete data (the transmission device or router cannot keep up with the transmission during transmission (Incomplete data) ・ Error due to control unit failure, processing system failure ・ Bit error ・ Transmission error due to noise, surge, line failure, etc.

FIG. 10 shows a configuration diagram of a main part of a conventional data transmission apparatus.

[0006] The data transmission apparatus includes a transmission side transmission apparatus 1 and a reception side transmission apparatus 2, which are connected to a network 3. A transmission device and a reception device can be connected to the transmission device 1 and the reception device 2, respectively.

[0007] The transmitting-side transmission device 1 includes a transmitting-side data control unit 11, a transmitting-side FCS calculating unit 12, and a selecting unit 13. The transmission data 51 is input to the transmission-side data control unit 11, the transmission-side FCS calculation unit 12, and the selection unit 13. The transmission-side data control unit 11 outputs the selection signal 54 to control the selection unit 13. The transmission-side FCS calculation unit 12 calculates the FCS 53 based on the transmission data 51. Selector 13
Selects the transmission data 51 or the FCS 53 and transmits the output data 52 to the network 3.

On the other hand, the receiving-side transmission device 2 includes a receiving-side data control unit 21 and a receiving-side FCS calculating unit 22. The input data 55 transmitted via the network 3
The data is input to the S control unit 22 and received as reception data 58. The reception-side FCS calculation unit 22 extracts the FCS from the reception data 58 and outputs confirmation data 56 to the reception-side data control unit 21 based on the FCS. The receiving-side data control unit 21 outputs a correct / wrong signal 57 of the received data according to the confirmation data 56.

The network 3 is an Ethernet, LA
N, WAN, ISDN line, B-ISDN line, and the like can be appropriately selected.

Next, FIG. 11 shows a flowchart for explaining a conventional transmitting / receiving operation.

When the program is started, in the transmitting side transmitting apparatus 1, in step S101, the transmitting side data control section 11 monitors whether or not the transmitting data 51 has the transmission error as described above. In parallel with this, the FCS of the transmission data 51 is transmitted to the transmission-side FCS calculation unit 1.
Calculate with 2. Next, in step S102, by controlling the selection unit 13 with the selection signal 54 from the data control unit 11, the transmission data 51 is output as the output data 52, and thereafter, it is determined whether or not there is no problem with the transmission data 51. I do. If it is determined that there is no problem with the transmission data 51, the transmission data 51 is transmitted as the output data 52 in step S103, and then the transmission-side data control unit 11
By controlling the selection unit 13 with the selection signal 54 from the CPU, the transmission-side FCS calculation unit 12 calculates the FC
S53 is output as output data 52. On the other hand, if there is a problem with the transmission data 51, the transmission-side data control unit 11 controls the selection unit 13 with the selection signal 54 so as not to transmit the FCS 53 in step S104.

On the other hand, the receiving-side transmission device 2 receives the input data 55 in step S 105, and concurrently transmits the F
Calculate CS. Here, in step S106,
The transmitting-side FCS calculating unit 12 confirms whether the transmitted FCS data and the calculated FCS match, and notifies the transmitting-side data control unit 11 by a confirmation signal 56. FCS
If they match, it is determined in step S107 that the received data 58 contains correct data, and the reception of the data is notified to the receiving device or the like by the correct / incorrect signal 57. Here, the correct / incorrect signal 57 includes information on the transmission error as described above, for example, a long frame, a short frame,
Correctness information such as an alignment error (when there is no 1 or 2 bits) and FCS mismatch are included. On the other hand, F
If the CSs do not match, it is determined in step S108 that the received data has an error, and the fact that the data will not be received is transmitted to the receiving apparatus using a true / false signal 57.

[0013]

However, when erroneous data transmitted and received by the receiving side is received as in the prior art, in step S106, the part corresponding to the FCS of the received data becomes the same value as the FCS calculated by accident. Sometimes. The reason is explained as follows.

For example, if the transmission data is incorrect in step S102, the FC
It will be transmitted without adding S. At this time, on the receiving side, the last N bits (in the case of IEEE 802.3, N = 3
Since 2) is recognized as FCS, input data 5
This is because the FCS of No. 5 may coincide with the calculated FCS by chance. Here, even if it is coincidence, since the amount of data to be transmitted can be enormous, the probability of coincidence cannot be ignored.

As a result, the FCS calculation unit 12 cannot recognize that the data is erroneous in the receiving-side transmission device 2 and treats the data as correct data.

In this case, conventionally, for example, the content of the received data is analyzed by a CPU at a higher level or the like, and as a result, it can be determined that erroneous data has been received. However, there is a problem that a load is imposed on the CPU.

In view of the above problems, the present invention has
In a data transmission apparatus of a frame format having an FCS such as SDN or LAPD, it is possible to recognize erroneous data without processing by a CPU at an upper level or the like, thereby reducing a load on the CPU and improving a processing capability. With the goal.

[0018]

According to a first aspect of the present invention, there is provided a calculation unit for obtaining an error detection code based on transmission data, and the calculation unit obtained by the calculation unit in accordance with an input inversion control signal. An inverting unit that outputs the error detection code as it is or inverted, a selecting unit that selects and outputs either the transmission data or the output of the inversion unit according to the input selection signal, and an error in the transmission data. By monitoring whether or not there is an error, if it is determined that there is an error, the inversion control signal controls the inversion unit to invert the error detection code, and the selection signal controls the selection unit to invert. And a data control unit for outputting the error detection code.

According to a second solution of the present invention,
A calculating unit for obtaining an N-bit error detection code based on the transmission data, an inverting unit for outputting the error detection code obtained by the calculation unit as it is or by inverting the error detection code according to the input inversion control signal; A selection unit for selecting and outputting either the transmission data or the output of the inversion unit according to the selected selection signal;
A buffer for accumulating bits, a shift register for outputting data transmitted by N bits of the transmission data, a second calculator for obtaining a second error detection code from an output from the shift register, A comparing unit that compares the last N bits stored in the unit with the second error detection code obtained by the second calculating unit;
It monitors whether there is an error in the transmission data, and when it is determined that there is an error, if the last N bits and the second error detection code match in the comparing section, the inversion control signal A data control unit for controlling the inversion unit to invert the error detection code, and controlling the selection unit by the selection signal to output the inverted error detection code. .

Further, according to a third solution of the present invention, the apparatus further comprises a generation unit which is selected by the selection unit and generates a stop frame or a false error detection code. Monitoring whether there is an error, if it is determined that there is an error, by controlling the selection unit by the selection signal, to select the stop frame or the false error detection code from the generation unit The data transmission device according to any one of claims 1 to 4, wherein the data transmission device outputs the data.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

1. 1. Outline of the Present Invention FIG. 1 is a flowchart illustrating an outline of a transmitting / receiving operation according to the present invention. Here, the main point of the present invention is to transmit an FCS different from the FCS calculation result when there is a problem with the transmission data when transmitting the transmission data.

The difference from the conventional flowchart shown in FIG. 11 is that, in particular, step S104 in FIG. 11 is replaced with that shown in step S201 in FIG. Other steps S201 to S203 and S20 in the present invention
Steps 5 to S208 are steps S10 in the conventional example, respectively.
Processing corresponding to 101 to S103 and S105 to S108 is executed. As described above, according to the conventional method of terminating the data in step S104, in the receiving-side transmission device 2, the received erroneous data and the calculated FCS may coincide. Therefore, in the present invention, by transmitting the fake FCS in step S201, the FCS does not match in the processing in the receiving side transmission device 2.

2. First Embodiment FIG. 2 shows a configuration diagram of a main part of a data transmission device according to a first embodiment of the present invention. The data transmission device includes a transmitting device 1 and a receiving device 2, which are connected to a network 3. A transmission device and a reception device can be connected to the transmission device 1 and the reception device 2, respectively.

The transmitting-side transmission device 1 includes a transmitting-side data control unit 11, a transmitting-side FCS calculating unit 12, a selecting unit 13, and an inverting unit 14. Transmission data 51 transmitted from the transmission device
Are the transmission-side data control unit 11 and the transmission-side FCS calculation unit 12
And the selection unit 13. Transmission side data control unit 11
Outputs the selection signal 54 and the inversion control signal 61 to control the selection unit 13 and the inversion unit 14, respectively. Sending side F
The CS calculator 12 calculates FCS data 53 based on the transmission data 51. For example, in the case of IEEE 802.3, CRC is calculated for transmission data, and as a result, 32-bit FCS data is generated.

The inverting section 14 receives the FCS data 53 output from the transmitting-side FCS calculating section 12 and outputs the FCS data 53 as it is or in reverse according to an inversion control signal 61. The selection unit 13 selects either the transmission data 51 or the inversion unit output 62 (inverted or non-inverted FCS) according to the selection signal 54 and transmits the output data 52 to the network 3 as output data 52.

On the other hand, the receiving side transmission device 2 is, as in the prior art,
A receiving-side data control unit 21 and a receiving-side FCS calculating unit 22 are provided. The input data 55 transmitted via the network 3 is input to the FCS control unit 22 and received as received data 58. Receiving-side FCS calculator 22
Extracts the FCS from the received data 58 and outputs confirmation data 56 to the receiving-side data control unit 21 based on the FCS. The receiving-side data control unit 21 outputs a correct / wrong signal 57 of the received data according to the confirmation data 56.

The network 3 includes LAN, WAN, IS
A DN line, a B-ISDN line, or the like can be appropriately selected.

Next, FIG. 3 shows a flowchart for explaining the transmission / reception operation of the first embodiment of the present invention.

When the program is started, in the transmitting side transmitting apparatus 1, the transmitting side data control unit 11 determines in step S301 whether or not the transmitting data 51 has caused the transmission error as described above in step S301. To monitor. In parallel with this, the FCS of the transmission data 51 is calculated by the transmission-side FCS calculation unit 12. Next, step S3
02, the selection signal 54 from the transmission-side data control unit 11
The transmission data 51 is output as output data 52 by controlling the selection unit 13 to determine whether the transmission data 51 has no problem such as a transmission error. If it is determined that there is no problem in the transmission data 51, step S301
Then, after transmitting the transmission data 51 as the output data 52, the selection unit 13 receives the selection signal 54 from the data control unit 11.
Is controlled, the FCS 53 which is the calculation result by the FCS calculation unit 12 is output as the output data 52.
On the other hand, if there is a problem such as a transmission error in the transmission data 51, in step S303, the transmission-side data control unit 11 of the transmission-side transmission device 1 determines that the transmission-side F
The FCS calculated by the CRC in the CS calculation unit 12 is converted into an inversion unit 14
Is controlled by an inversion control signal 61 so that N bits (N = 1, 2,..., 32, etc.) are inverted and transmitted. As the timing, for example, a point when it is found that erroneous data is being transmitted (conventionally, a state in which transmission data is terminated) can be appropriately determined.

Here, the bit inversion can be appropriately performed such as all bit inversion, last or first one bit or four bit inversion, or the like. Also, the FCS is not limited to 32 bits, and the number of bits can be set as appropriate.

On the other hand, the processing operation in the receiving side transmission device 2 is the same as the conventional one. That is, steps S305 to S308 in the present invention respectively execute processes corresponding to steps S105 to S108 in the conventional example.

By such processing, the received FCS
Does not match the FCS calculated on the receiving side, so that the receiving-side transmission device 2 cannot erroneously recognize that the data is correct as in the related art.

According to the present invention, according to the above-described method, it is unlikely that the FCS matches in any data.

3. Second Embodiment FIG. 4 shows a configuration diagram of a main part of a data transmission device according to a second embodiment of the present invention. The data transmission device includes a transmitting device 1 and a receiving device 2, which are connected to a network 3. A transmission device and a reception device can be connected to the transmission device 1 and the reception device 2, respectively.

The transmitting-side transmission device 1 includes a transmitting-side data control unit 11, a transmitting-side FCS calculating unit 12, a selecting unit 13, and an inverting unit 1.
4, a shift register unit 15, a second FCS calculation unit 16, a buffer unit 17, and a comparison unit 18. The shift register unit 15 and the buffer unit 17 can have, for example, 32 bits, the same bit number as the FCS bit number. In the following description, it is assumed that these bits are 32 bits, but these bits can be appropriately set as needed.

Transmission data 51 transmitted from the transmission device
Are a transmission-side data control unit 11, a selection unit 13, a buffer unit 17, a transmission-side FCS calculation unit 12, and a shift register unit 15.
Is input to The transmission-side data control unit 11 selects the selection signal 5
4 and the inversion control signal 61 to output
3 and the reversing unit 14 are controlled. Transmission side FCS calculation unit 12
Calculates the FCS 53 based on the transmission data 51.
For example, in the case of IEEE802.3, CRC calculation is performed on the transmission data 51, and as a result, a 32-bit FCS is generated. The selection unit 13 selects either the transmission data 51 or the output of the inversion unit (inversion or non-inversion of FCS) according to the selection signal 54 and transmits the output data 52 to the network 3 as output data 52. The inverting unit 14 is configured to transmit the FCS calculating unit 12 on the transmission side.
The FCS 53 output from is input and the inversion control signal 61
And outputs the FCS 53 as it is or after inverting it.

Further, in this embodiment, the buffer unit 17 temporarily stores transmission data. On the other hand, the delayed transmission data 51 is transferred to the second F
The second FCS 63 is calculated by the second FCS calculator 16 and input to the CS calculator 16. The comparing unit 18 compares the FCS stored in the buffer unit 17 with the second FCS calculating unit 1
By comparing the second FCS 63 calculated in step 6 with the second FCS 63, a match or mismatch signal is transmitted to the data control unit 11.

On the other hand, the reception-side transmission device 2 is a conventional or first transmission device.
As in the first embodiment, a reception-side data control unit 21 and a reception-side FCS calculation unit 22 are provided. The input data 55 transmitted via the network 3 is input to the FCS control unit 22 and received as received data 58.
The receiving-side FCS calculator 22 calculates the FCS
And outputs confirmation data 56 to the reception-side data control unit 21 based on the FCS. The receiving-side data control unit 21
In accordance with the confirmation data 56, a correct / incorrect signal 57 of the received data is output.

Next, FIG. 5 is a flowchart for explaining the transmission / reception operation according to the second embodiment of the present invention. When the program is started, the transmission-side data control unit 1 of the transmission-side transmission device 1 is set in step S401.
1 controls the selection unit 13 to output the transmission data 51 as output data 52, and also controls the transmission-side FCS calculation unit 1
2 performs FCS calculation based on the transmission data 51. In parallel with this, the buffer unit 17 stores, for example, the last 32 bits in the transmission data. At the same time, the transmission data is serially input to the shift register unit 15, and data that is delayed by, for example, 32 bits from the actually transmitted data is output. The second FCS calculator 16 calculates a second FCS 63 of the data delayed from the shift register 15 by 32 bits.

Next, in step S402, it is determined whether or not the transmission data 51 has a problem such as a transmission error. Here, if there is no problem, in step S403, the transmission-side data control unit 11 appends the FCS calculated by the transmission-side FCS calculation unit 12 that has controlled the selection unit 13 by the selection signal 54 to the end of the transmission data 51 and outputs the output data. The transmission is performed as 52, and the transmission is completed.

On the other hand, if there is a problem with the transmission data 51, the second FCS 63 calculated by the second FCS calculation unit 16 and the last 32 bits of the transmission data 51 (output of the buffer 14) are compared in step S404. 18
To compare. If the two FCSs do not match in step S404, it means that the FCS has been transmitted as erroneous transmission data in step S405, so that it is possible to determine on the receiving side. Stop sending. On the other hand, if both FCSs match in step S404, the transmission-side data control unit 11 sends the inversion unit 14 based on the inversion control signal 61 in step S406.
Is controlled to calculate the calculated F in the same manner as in the first embodiment.
It inverts CS and outputs an inverting section output 62.

Note that the output of the comparing section 18 is directly applied to the inverting section 1
4 to control the inversion of the inversion unit 14.

FIG. 6 is a block diagram showing a case where the inverting section is directly controlled. As shown in the figure, the comparison result of the comparison unit 18 directly controls the inversion unit 14. That is, in the second embodiment, in step S406, the comparison unit 18
The inversion control signal 64 controls the inversion unit 14 to invert the calculated FCS, and outputs an inversion unit output 62. The direct inversion control signal 64 allows the transmission-side data control unit 1
1 can be reduced.

In the first embodiment, when a transmission error or the like occurs, the inverted FCS is output even when it is not necessary. Therefore, in the second embodiment, the first FCS is output in terms of transfer efficiency. It becomes better than the embodiment. In the second embodiment, the buffer 14, the second FCS calculation unit 16, the comparison unit 1
8 and the shift register unit 15 are required, but in practice, the buffer 14 and the second FCS calculation unit 16
Are not so complicated, since they could be constructed as identical. According to the second embodiment, as described above, it is unlikely that the FCS matches on the receiving side for any data.

4. Third Embodiment FIG. 7 shows a configuration diagram of a main part of a data transmission device according to a third embodiment of the present invention. The data transmission device includes a transmitting device 1 and a receiving device 2, which are connected to a network 3. A transmission device and a reception device can be connected to the transmission device 1 and the reception device 2, respectively. The receiving-side transmission device 2 and the network 3 are the same as in the above-described embodiment.

The transmitting-side transmission device 1 includes a transmitting-side data control unit 11, a transmitting-side FCS calculating unit 12, a selecting unit 31, and a generating unit 32. Transmission data 51 transmitted from the transmission device
Are the transmission-side data control unit 11 and the transmission-side FCS calculation unit 12
And to the selection unit 31. The generating unit 32 generates a stop frame 65. The stop frame 65 has data indicating an error, such as “0111110”, all bits “1”, or all bits “0”. In ISDN, if seven or more consecutive “1” s mean a data error, this can be used. The transmission-side data control unit 11 outputs the selection signal 54 to control the selection unit 31. The transmission-side FCS calculation unit 12 calculates the FCS 53 based on the transmission data 51. For example, IEEE802.
In the case of 3, the CRC of the transmission data 51 is calculated, and as a result,
Generate 32-bit FCS. The selection unit 13 selects one of the transmission data 51, the FCS 53, and the stop data 65, and transmits the selected data as output data 52 to the network 3.

The operation is realized by replacing step S201 in the first embodiment as follows, and the other steps are the same as those in the first embodiment.

That is, the transmission-side FCS calculation unit 12 outputs the transmission data 51 as the output data 52 while
Perform CS calculation. When determining that a problem such as a transmission error has occurred in the transmission data 51, the transmission-side data control unit 11 controls the selection unit 31 with the selection signal 54 and selects the stop frame 61 as an appropriate frame or final data of the FCS. Then, it is output as output data 52.

According to the third embodiment, when the receiving-side transmission device 2 detects the stop frame 65, it
An error in received data can be detected without calculating or checking CS.

As in the third embodiment, the technical concept of providing a stop frame by the generation unit 32 instead of the inversion unit 14 for inverting the FCS is as follows.
It can also be applied in combination with the above-described embodiments as appropriate.
For example, according to the instruction of the host or a manual, the inverted FC
It can be configured to output either S or stop frame.

In place of the stop frame, a fake FCS can be used as appropriate.

5. Fourth Embodiment FIG. 8 shows a configuration diagram for a switching operation of a data control unit. In this embodiment, a switch setting unit 81 and a determination unit 82 are added to the transmission-side data control unit 11 of the transmission-side transmission device 1 in the above-described embodiment.

The switch setting unit 81 is a transmission data control unit 1
In the processing of No. 1, the processing (transmission of the inverted FCS or the stop frame) when the transmission data has an error is performed as in the above-described embodiment, or the F
This is a setting unit for executing switching between sending CS and sending CS. The switching setting unit 81 is switched by the control of the determining unit 82. In the determination unit 82,
The processing speed of the PU is compared with the transmission speed of the FCS, and a control signal is appropriately output so as to switch to a more advantageous one.

For example, in the first and second embodiments, the processing time of the CPU in the upper layer etc. is
If S is faster than traveling over the network,
Or, in the third embodiment, when the conventional technology is more advantageous, such as when the stop frame check time is faster than the time when the FCS is transmitted through the network,
It is possible to switch to the processing of the prior art. On the other hand, if the speed relationship is reversed, it is possible to switch to the processing as in the first to third embodiments.

The switch setting unit 81 can be automatically monitored and monitored by the host computer, and a separate detector such as a processing speed can be provided and controlled by its detection output.
Further, it can be realized by an appropriate means such as a configuration in which a changeover switch such as a dip switch is provided and manually set.

According to the fourth embodiment, the fastest pattern can be selected according to the situation.

6. Application to System FIG. 9 shows an example of a system configuration diagram. In the figure, LAN
(A) to (C) and the system configuration to which the ISDN is connected are shown. A bridge BR is provided between the LAN (A) and the LAN (C), and the LALAN (C) and the LAN (B)
A gateway GW is provided between them, and a router RTR is provided between the LAN (C) and ISDN.

The present invention can be applied to the bridge BR, gateway, router RTR, and the like.

Further, the following configuration is also possible. First, a sufficient buffer capable of storing transmission data is created on the transmission side, and all transmission data is secured once in this buffer. Thus, if a problem occurs in transmission data or transfer data, the data can be discarded before transmission. In this case, at least IEEE802.3
In the case of, a memory having a prescribed maximum data amount (1518 bytes) is required. In this way, all data can be stored in a router or the like.

Note that the respective devices of the transmission side transmission device 1 and the reception side transmission device 2 (for example, a data control unit, an FCS calculation unit, etc.) can be shared as appropriate.

[0061]

According to the present invention, on the data receiving side,
Erroneous data having a problem on the transmission side can be reliably discarded in a lower layer without being processed by a CPU in an upper layer. As in the past, when the upper-layer CPU had determined whether or not there was a problem with the data, it was thought that the burden would be increased and the processing would be increased, but this would result in unnecessary processing. And the processing capability of the CPU can be improved.

Further, according to the present invention, when a stop bit for checking a data error is provided after an FCS, an error such as a transmission error can be found without processing the frame.

According to the present invention (Embodiment 4),
When the speed of the CPU on the receiving side is high, the method can be switched to the conventional method, so that the method with the highest processing speed can be selected according to the situation.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an outline of a transmission / reception operation of the present invention.

FIG. 2 is a configuration diagram of a main part of the data transmission device according to the first embodiment of the present invention.

FIG. 3 is a flowchart for explaining a transmission / reception operation according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part of a data transmission device according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating a transmission / reception operation according to the second embodiment of the present invention.

FIG. 6 is a configuration diagram in a case where an inverting unit is directly controlled.

FIG. 7 is a configuration diagram of a main part of a data transmission device according to a third embodiment of the present invention.

FIG. 8 is a configuration diagram for a switching operation of a data control unit.

FIG. 9 is a system configuration diagram.

FIG. 10 is a configuration diagram of a main part of a conventional data transmission device.

FIG. 11 is a flowchart for explaining a conventional transmission / reception operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission-side transmission device 2 reception-side transmission device 11 transmission-side data control unit 12 transmission-side FCS calculation unit 13 selection unit 14 inversion unit 15 shift register 16 second FCS calculation unit 17 buffer 18 comparison unit

Claims (12)

[Claims] A calculating section for obtaining an error detection code based on transmission data; and an inverting section for outputting the error detection code obtained by the calculating section as it is or by inverting the error detection code in accordance with an input inversion control signal. A selection unit that selects and outputs either the transmission data or the output of the inversion unit according to the input selection signal; and monitors whether there is an error in the transmission data and determines that there is an error. A data control unit for controlling the inversion unit by the inversion control signal to invert the error detection code and controlling the selection unit by the selection signal to output the inverted error detection code. Data transmission equipment equipped. 2. A calculation unit for obtaining an N-bit error detection code based on transmission data, and outputting the error detection code obtained by the calculation unit as it is or after inverting it according to an input inversion control signal. An inverting unit, a selecting unit that selects and outputs either the transmission data or the output of the inverting unit in accordance with the input selection signal, a buffer unit that accumulates the last N bits of the transmission data, A shift register unit that outputs data delayed by N bits, a second calculation unit that obtains a second error detection code based on an output from the shift register unit, and the last N bits accumulated in the buffer unit. A comparator for comparing the second error detection code obtained by the second calculator with the second error detection code; and monitoring whether or not the transmission data has an error. If it is determined that there is, when the last N bits match the second error detection code in the comparison unit, the inversion unit controls the inversion unit by the inversion control signal to invert the error detection code, and A data control unit for controlling the selection unit by a signal to output the inverted error detection code. 3. A calculation section for obtaining an N-bit error detection code based on transmission data, and outputting the error detection code obtained by the calculation section as it is or after inverting it according to an input inversion control signal. An inverting unit, a selecting unit that selects and outputs either the transmission data or the output of the inverting unit in accordance with the input selection signal, a buffer unit that accumulates the last N bits of the transmission data, A shift register unit that outputs data delayed by N bits, a second calculation unit that obtains a second error detection code based on an output from the shift register unit, and the last N bits accumulated in the buffer unit. The second error detection code obtained by the second calculation unit is compared with the second error detection code, and if they match, the inversion unit is controlled by the inversion control signal. A comparison unit for inverting the error detection code, and monitors whether there is an error in the transmission data, and when it is determined that there is an error, the selection unit controls the selection unit with the selection signal to invert. A data transmission device comprising: a data control unit for outputting the error detection code. 4. The data control unit monitors whether there is an error in the transmission data, and when it determines that there is an error, the comparing unit checks the last N bits and the second error detection code. 4. The data transmission device according to claim 2, wherein, when does not match, the selection signal is used to control the selection unit to stop outputting the transmission data. 5. 5. A data processing apparatus further comprising: a generation unit that is selected by the selection unit and generates a stop frame or a false error detection code, wherein the data control unit monitors whether there is an error in the transmission data, 4. The method according to claim 1, wherein when it is determined that there is an error, the selection unit controls the selection unit to select and output the stop frame or the false error detection code from the generation unit. 5. 5. The data transmission device according to any one of 4. 6. A calculation unit for obtaining an error detection code based on transmission data, a generation unit for generating a stop frame or a false error detection code, and the calculation unit obtained by the calculation unit according to an input inversion control signal. An inverting unit that outputs the error detection code as it is or inverted, a selecting unit that selects and outputs either the transmission data or the output of the inversion unit according to the input selection signal, and an error in the transmission data. Monitoring whether or not there is, if it is determined that there is an error, the data control for outputting the stop frame or the false error detection code from the generation unit by controlling the selection unit by the selection signal Data transmission device comprising: 7. The data control unit monitors whether there is an error in the transmission data, and when it is determined that there is no error, controls the inversion unit by the inversion control signal to control the error detection code. 6. The data transmission device according to claim 1, wherein the data transmission device outputs the error detection code by controlling the selection unit according to the selection signal. 8. The data control unit controls the selection unit according to the selection signal,
The data transmission apparatus according to claim 1, wherein after outputting the transmission data to the line, the error detection code or the inverted error detection code is output to the line. 9. The data control unit controls the selection unit according to the selection signal,
9. The error detecting code according to claim 1, wherein the error detecting code or the inverted error detecting code is output to a frame for checking a data error in a frame format of the transmission data. Data transmission device. 10. A switching setting section for setting whether or not to execute the error check code inversion processing by the inversion section, wherein the switching setting section sets not to execute the inversion processing. 10. The data transmission device according to claim 1, wherein the inverting unit outputs the error detection code as it is, regardless of whether there is an error in the transmission data. 11. A processing time of a processor for judging an error in the transmission data is compared with a transmission time of the error check code or a check time of the stop frame. The data transmission device according to claim 10, further comprising a determination unit for setting. 12. A receiving-side calculator for calculating an error check code based on input data input from the line and outputting confirmation data; the confirmation data calculated by the receiving-side calculator; The data transmission apparatus according to any one of claims 1 to 11, further comprising: a reception-side data control unit that outputs a correct / error signal by comparing with the error check code.