JP2004187117A - Serial data communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the magnetic saturation of pulse transformers at a low cost by simple processing in serial data communication using the pulse transformers. <P>SOLUTION: In serial data communication method for transmitting or receiving transmission object data as serial data through a communication line CL provided with the pulse transformers 13 and 23, bit inverted data of the transmission object data is calculated, and the transmission object data and the bit inverted data are alternately transmitted or received by one piece of data at a time. Otherwise, each bit of the transmission object data is divided into a plurality of groups, real transmission data is generated by alternately arranging data of each group and bit inverted auxiliary data composed at negative values of each bit of the group in a line of digits, and the real transmission data is transmitted to the communication line. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a serial data communication method for transmitting or receiving transmission target data as serial data via a communication line provided with a pulse transformer.
[0002]
[Prior art]
Such a serial data communication method uses a serial communication via a communication line provided with a pulse transformer in order to electrically insulate the data transmitting side and the data receiving side so that the ground level is independent. It performs data communication in a format.
In such data communication, there is a problem that if a DC signal is continuously applied to the pulse transformer, so-called magnetic saturation occurs, and the signal is not transmitted correctly.
For this reason, conventionally, as described in Patent Literature 1 and Patent Literature 2, an encoder IC that encodes transmission target data so as to shorten a time interval in which bits having the same value continues is generally provided. Was.
[0003]
[Patent Document 1]
JP-A-7-107121 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2001-156682
[Problems to be solved by the invention]
However, in the above-described conventional configuration, a dedicated encoder IC is required to execute a complicated encoding process, and there is a problem that a circuit configuration is complicated.
The present invention has been made in view of such circumstances, and has as its object to prevent magnetic saturation of a pulse transformer at low cost by simple processing.
[0005]
[Means for Solving the Problems]
By providing the configuration according to claim 1, in a serial data communication method for transmitting or receiving transmission target data as serial data via a communication line provided with a pulse transformer, bit inverted data of the transmission target data is obtained. The data to be transmitted and the bit-reversed data are alternately transmitted or received for each data.
[0006]
From the viewpoint of magnetic saturation, the worst condition for the pulse transformer is that if the bit length of the data to be transmitted is 8 bits, the bit value of each digit is the same, such as "11111111" or "00000000". This is the case of data that is a value.
In order to transmit and receive data properly even under such conditions, it is necessary to select a pulse transformer that does not cause magnetic saturation at a time interval at which data of at least 8 bits is transmitted.
[0007]
However, even if magnetic saturation does not occur during the time interval, and if data of strict conditions such as "11111111" or "00000000" continues after that, the magnetization by the preceding data is changed by the pulse transformer. , Magnetic saturation occurs in a time shorter than the time interval.
Therefore, by alternately transmitting or receiving the transmission target data and the bit-inverted data generated by bit-inverting the bit value of each digit of the transmission target data, under the worst condition, “11111111” or “00000000” This ensures that the data to be transmitted is followed by a bit-reversed value of the data to be transmitted, "00000000" or "11111111", thereby preventing magnetic saturation of the pulse transformer.
Since the bit-inverted data of the transmission target data as described above can be easily generated by software processing by an operation for calculating a negative value of the data, magnetic saturation of the pulse transformer can be prevented at low cost by simple processing. Can be.
Moreover, on the receiving side of the serial data communication, the data to be transmitted is compared with the bit-reversed data, and if the corresponding digits are not bit-reversed values, the data is not properly transmitted / received, and It is possible to detect that a communication abnormality has occurred, and to contribute to improving the quality of data communication.
[0008]
The data length of "1 data" of the transmission target data may be a data length handled as "1 data" in an arithmetic processing process in a processing device such as a microprocessor that executes the processing of claim 1. Alternatively, the data length may be “1 data” after being converted into serial data.
When the data length of “1 data” is the data length of “1 data” on the processing device side, simple software processing is of course possible, and when the data length of “1 data” is serial data, In general, one data of serial data has a data length for which arithmetic processing is easy even in a microprocessor or the like, and simple software processing can be performed.
[0009]
Also, by providing the configuration according to claim 2, in a serial data communication method for transmitting or receiving transmission target data as serial data via a communication line provided with a pulse transformer, each bit of the transmission target data is Divided into a plurality of groups, the data of each group and the bit-reversed auxiliary data composed of the negative value of each bit of the group, the actual transmission data is generated by alternately arranging in the arrangement of digits, The actual transmission data is transmitted to the communication line.
[0010]
That is, one transmission target data is divided into a plurality of groups (including a case where the number of bits belonging to one group is 1 bit), and the data of the group and the negative value of each bit of the group are considered. The actual transmission data is reconstructed from the transmission target data so that the constituted data (bit inversion auxiliary data) are alternately arranged.
Therefore, the original data and the bit inversion auxiliary data change in a short period, which makes it difficult for the pulse transformer to cause magnetic saturation, and alleviates the condition for the magnetic saturation of the pulse transformer. In this case, the smaller the number of bits in each group, the shorter the period of change between the original data and the bit-reversed auxiliary data, making the pulse transformer less likely to cause magnetic saturation.
Thus, magnetic saturation of the pulse transformer can be prevented at low cost by simple processing.
In addition, on the receiving side of the serial data communication, the original data (part of the transmission target data) and the bit-reversed auxiliary data are compared, and if the corresponding digits are not bit-reversed values, In addition, it is possible to detect that data is not properly transmitted / received and some communication abnormality has occurred, which can contribute to improvement of data communication quality.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a serial data communication method according to the present invention will be described with reference to the drawings.
<First embodiment>
In the first embodiment, as shown in FIG. 1, a case where data communication is performed between two control devices A and B provided for managing and controlling various devices (not shown) is illustrated. The invention will be described.
Communication interfaces 1 and 2 are attached to the control devices A and B, respectively, and the control devices A and B exchange data via the communication interfaces 1 and 2.
[0012]
[Configuration of Communication Interfaces 1 and 2]
The configurations of the communication interfaces 1 and 2 are completely common, and UART circuits 11 and 21 for converting 8-bit parallel data received from the control devices A and B into a general-purpose serial communication data format, and receivers 12a and 22a and a driver 12b. , 22b, pulse transformers 13 and 23, and other components such as resistors and capacitors. Therefore, the control device A and the control device B transmit or receive the transmission target data as serial data via the communication line CL provided with the pulse transformers 13 and 23.
As the UART circuits 11 and 21 and the line transceivers 12 and 22, a general-purpose serial data communication IC such as RS-422 or RS-485 can be used as it is.
[0013]
[Data transmission / reception processing]
When performing data communication via the communication interfaces 1 and 2 configured as described above, the control devices A and B, for example, when continuously transmitting 8-bit length data “11111111”, the communication interface 1 , 2 cause the pulse transformers 13 and 23 to be magnetically saturated, so the transmission data is processed on a program.
[0014]
Specifically, when receiving a data transmission request from a device under management, the control devices A and B start the processing shown in FIG. The processing of FIG. 3 is stored in the control devices A and B as a program.
Hereinafter, a case where the signal is transmitted from the control device A to the control device B will be described as an example.
First, the control device A fetches data to be transmitted (hereinafter referred to as “transmission target data”) in byte (8-bit) units from a device under management (step # 1).
When the data has been completely fetched from the device (step # 2), an operation for calculating a negative value is performed for each byte data, so that the value of each bit becomes the negative value of the corresponding digit of the transmission target data. Is obtained (step # 3). That is, when the transmission target data is, for example, “11001101”, the bit-inverted data of the transmission target data is “00110010”.
[0015]
Next, a transmission data sequence is organized so that the transmission target data and the bit-inverted data obtained from the data are alternately arranged for each data (step # 4). The data is sequentially written into the buffer of the UART circuit 11 of the communication interface 1 via the bus line as parallel data (step # 5).
The UART circuit 11 converts the 1-byte data written in the buffer into an 8-bit bit string, and adds a start bit ("0") for start-stop synchronization and a stop bit ("1") before and after the bit string. ) Is added, and a signal bit ("1") indicating a standby state is added before and after to generate serial transmission data, which is sequentially sent to the driver 12b of the line transceiver 12. Thus, the transmission target data and the bit-reversed data are transmitted alternately for each data.
When the control device A writes all data into the buffer of the UART circuit 11, the process ends (step # 6).
[0016]
As a result of this data transmission, a signal as shown in FIG.
FIG. 2A shows a case where 8-bit data “01010101” is sequentially transmitted from the LSB, and FIG. 2B shows a case where the pulse transformers 13 and 23 are in a state where magnetic saturation is most likely to occur. The case where “11111111” is transmitted is shown.
In the case of FIG. 2A as well as in the case of FIG. 2B, which is the strictest condition, the data “11111111” is followed by the bit-inverted data “00000000” of the data. Can be reliably prevented.
[0017]
The data input to the communication interface 2 of the control device B via the pulse transformers 13 and 23 is taken into the control device B as 8-bit parallel data.
Since the communication interface 2 alternately receives the transmission target data and the bit-reversed data for each data, the control device B removes the bit-reversed data from the received data and converts the original transmission target data. Extract. At this time, since the transmission target data and the bit-reversed data are in a bit-reversed relationship, it is also possible to check whether or not the communication has been normally completed by executing an operation such as XOR or AND between the bits. It is possible.
The case where data is transmitted from the control device A to the control device B has been described above. However, when data is transmitted from the control device B to the control device A, exactly the same processing as described above is executed.
[0018]
<Second embodiment>
Next, a second embodiment of the present invention will be described.
In the second embodiment, the configuration of the communication interfaces 1 and 2 shown in FIG. 1 is completely the same as that of the first embodiment, and the data transmission / reception processing executed by the control devices A and B is different from that of the first embodiment. .
Hereinafter, a data transmission / reception process according to the second embodiment will be described.
[0019]
[Data transmission / reception processing]
The data transmission / reception processing of the control devices A and B according to the second embodiment has the same processing purpose as that of the first embodiment, and the control devices A and B transmit data via the communication interfaces 1 and 2 having the above configuration. For example, when the data “11111111” having a length of 8 bits is continuously transmitted when the communication is performed, the pulse transformers 13 and 23 are magnetically saturated if the data is transmitted through the communication interfaces 1 and 2 as it is. Is processed on the program.
[0020]
Specifically, when receiving a data transmission request from a device under management, the control devices A and B start the processing shown in FIG. 3 as in the first embodiment. The processing in FIG. 3 is the same as that in the first embodiment in that the processing is stored in the control devices A and B as a program. As will be described later, the second embodiment differs from the first embodiment in the processing content in the processing of step # 4 in FIG.
Hereinafter, a case where the signal is transmitted from the control device A to the control device B will be described as an example.
[0021]
First, the control device A fetches data to be transmitted (hereinafter referred to as “transmission target data”) in byte (8-bit) units from a device under management (step # 1).
When the data is completely fetched from the device (step # 2), a calculation for obtaining a negative value is performed for each byte data, whereby the value of each bit is constituted by the negative value of the transmission target data. Bit inverted data to be obtained (step # 3). That is, when the transmission target data is, for example, “11001101”, the bit-inverted data of the transmission target data is “00110010”.
[0022]
Next, based on the transmission target data and the bit-reversed data, actual transmission data to be actually transmitted to the control device B is organized (Step # 4).
This actual transmission data divides each bit of the transmission target data into a plurality of groups, and converts the data of each group and the bit-reversal auxiliary data constituted by the negation value of each bit of the group into a digit. They are generated by arranging them alternately in a row.
More specifically, each bit of the transmission target data is divided into a plurality of groups having the same number of bits, and a bit constituted by the data of each group and a negative value of the data of each bit of the group. The actual transmission data is generated by alternately arranging the inverted auxiliary data in the arrangement of the digits.
As a result, it is guaranteed that the signal changes within one data, whereby the pulse transformer is less likely to cause magnetic saturation, and the condition for magnetic saturation of the pulse transformer can be relaxed.
Moreover, the groups that are the units for generating the bit-reversed auxiliary data are equally divided so that the number of bits belonging to each group is the same, so that the processing for generating the actual transmission data is more easily performed by software. Can be done.
[0023]
Since the number of bits belonging to each group is the same, the number of bits in each group is a divisor of the bit length of the transmission target data. If the bit length of the transmission target data is 8 bits as described above, “1 bit” , "2 bits" or "4 bits". In the second embodiment, a case where the number of bits of each group is 1 is exemplified.
[0024]
Therefore, when the transmission target data is “Da ₇ Da ₆ Da ₅ Da ₄ Da ₃ Da ₂ Da ₁ Da ₀ ” (Da _{0 to} Da ₇ indicate the bit values of each bit), each element is “ Da ₇ "," Da ₆ "," Da ₅ "," Da ₄ "," Da ₃ "," Da ₂ ", divided into eight groups is" Da ₁ "and" Da ₀ ", corresponding to those The bit inversion auxiliary data “/ Da ₇ ”, “/ Da ₆ ”, “/ Da ₅ ”, “/ Da ₄ ”, “/ Da ₃ ”, “/ Da ₂ ”, “/ Da ₁ ” and “/ "Da ₀ " (where "/" means a negative value of each bit) and "Da ₃ " for the lower 4 bits of the transmission target data by alternately arranging the digits. _{/ Da 3 Da 2 / Da 2} Da 1 / Da 1 Da 0 / Da 0 " 8-bit data, with respect to the upper 4 bits to generate two real transmission data of 8-bit data _{"Da 7 / Da 7 Da 6 /} Da 6 Da 5 / Da 5 Da 4 / Da 4 ". That is, when the transmission target data is, for example, “11001101”, the actual transmission data is “10100110” for the lower 4 bits of the transmission target data and “10100101” for the upper 4 bits. The process of generating the actual transmission data includes, for example, a masking process and a bit shift process based on a logical product of the transmission target data and the bit-inverted data with data in which only bits to be extracted are set to “1”, This is performed by executing a process for calculating the logical sum of the processing results.
[0025]
Next, the actual transmission data is sequentially written into the buffer of the UART circuit 11 of the communication interface 1 via the bus line for each byte (step # 5).
The UART circuit 11 converts the 1-byte data written in the buffer into an 8-bit bit string, and adds a start bit ("0") for start-stop synchronization and a stop bit ("1") before and after the bit string. ) Is added, and a signal bit ("1") indicating a standby state is added before and after to generate serial transmission data, which is sequentially sent to the driver 12b of the line transceiver 12.
When the control device A writes all data into the buffer of the UART circuit 11, the process ends (step # 6).
[0026]
By this data transmission, a signal as shown in FIG. 4 is applied to the pulse transformer 13. FIG. 4 shows a case where 8-bit data “11111111” is transmitted.
As described above, even if the "stop bit" and the "standby state" bit are inserted, the same value bit does not continue more than 4 bits, so that the so-called pulse transformer having a small ET product and easily magnetically saturated can be surely used. In addition, magnetic saturation can be prevented.
[0027]
The data input to the communication interface 2 of the control device B via the pulse transformers 13 and 23 is taken into the control device B as 8-bit parallel data.
The control device B extracts the bit value of the element of the data to be transmitted from the received data and reconstructs it into one data.
The case where data is transmitted from the control device A to the control device B has been described above. However, when data is transmitted from the control device B to the control device A, exactly the same processing as described above is executed.
[0028]
<Other embodiments>
Hereinafter, other embodiments of the present invention will be listed.
(1) In the second embodiment, when the actual transmission data is obtained, the case where the transmission target data is divided into eight groups in which the number of bits in each group is 1 bit is exemplified. The number of bits may be divided into four groups of two bits, or each group may be divided into two groups of four bits.
(2) In the first embodiment and the second embodiment, the case where the bit length of one data is 8 bits is exemplified. However, data having a bit length longer than 8 bits or data having a shorter bit length is used. The present invention can be applied to serial communication.
[0029]
(3) In the second embodiment, the case where the data to be transmitted has 8 bits is shown. However, even in the case of data having an odd number of bits, dummy bits (fixed to 1 or 0) are set to the MSB of the data to be transmitted, The present invention can be applied to a case where the number of bits is set to an even number by processing such as providing the LSB or a position before or after the center bit. In this case, normally, the 7-bit data becomes 16-bit or 15-bit transmission data. However, when the reception of the data is completed, if the dummy bit and the inverted data of the dummy bit are removed, the original 7-bit data is removed. Can be restored as data.
[0030]
(4) In the second embodiment, the case where the transmission target data is 8 bits and has a divisor other than “1” and the data length value (“8”) is shown. If an agreement is set between the receiving side and the receiving side, the data is an odd number of bits having no divisor other than the value of "1" and the data length, or the transmission target data is divided into a plurality of bits having the same number of bits. The present invention can be applied to the case of dividing into groups.
For example, the transmission target data having a length of 7 bits is transmitted as 7 bits by adding the lower 3 bits and its inverted data 3 bits, and the upper 4 bits to 1 bit, and then transmitting the upper 4 bits. Transmission, reception, and restoration to actual data can be realized by setting such that the remaining bits of the previously transmitted bits and the inverted data of the upper 4 bits are transmitted. Therefore, the present invention can be implemented regardless of the transmission target data length. In this case, there may be a case where about 2 bits cannot be arranged alternately in the arrangement of digits, but this can be performed when there is a sufficient margin for magnetic saturation of the pulse transformer.
[0031]
(5) In the second embodiment, the transmission target data and the bit-reversed data are subjected to a masking process and a bit shift process by a logical product of data in which only bits to be extracted are set to “1”, and the processes thereof. Although the case where the actual transmission data is generated by executing a process of taking a logical sum of the results is illustrated, various methods can be used as a method of generating the actual transmission data. It may be as follows.
That is, when the transmission target data is _{"Da 7 Da 6 Da 5 Da 4} Da 3 Da 2 Da 1 Da 0 ", the as actual transmission data, 8-bit data "Da produced by odd bits of transmitted data _{7 / Da 7 Da 5 / Da} 5 Da 3 / Da 3 Da 1 / Da 1 and "8-bit data" _{Da 6 / Da 6 Da 4 /} Da 4 Da 2 / Da produced by the even bits of the transmission target data ₂ Da ₀ / Da ₀ .
[0032]
Hereinafter, the processing procedure is listed.
{Circle around (1)} From the transmission target data “Da ₇ Da ₆ Da ₅ Da ₄ Da ₃ Da ₂ Da ₁ Da ₀ ”, the bit inversion data “/ Da ₇ / Da ₆ / Da ₅ / Da ₄ / Da ₃ / Da ₂ / Da” ₁ / Da ₀ "to create.
▲ 2 ▼ bit inverted data by one bit shifted to a lower digit side _{"* / Da 7 / Da 6 /} Da 5 / Da 4 / Da 3 / Da 2 / Da 1 " (the "*" is an arbitrary value) create.
▲ 3 ▼ by masking the data created by the transmitted data and the ▲ 2 ▼, _{"Da 7 0 Da 5 0 Da 3} 0 Da 1 0 " and _{"0 / Da 7 0 / Da 5} 0 / Da 3 0 / Da ₁ ".
▲ 4 ▼ the ▲ 3 ▼ at by combining the two data obtained, one of the two real transmission data _{"Da 7 / Da 7 Da 5 /} Da 5 Da 3 / Da 3 Da 1 / Da 1 " Create
{Circle around (5)} The data to be transmitted is shifted by one bit to the upper digit side to create “Da ₆ Da ₅ Da ₄ Da ₃ Da ₂ Da ₁ Da ₀ *” (“*” is an arbitrary value).
▲ 6 ▼ the ▲ 5 ▼ masked processed data and the bit inverted data created in _{"Da 6 0 Da 4 0 Da 2} 0 Da 0 0 " and _{"0 / Da 6 0 / Da 4} 0 / Da 2 ₀ / Da 0 "to create.
{Circle around (7)} The two data obtained in the above [6] are combined, and the remaining one of the two actual transmission data, “Da ₆ / Da ₆ Da ₄ / Da ₄ Da ₂ / Da ₂ Da ₀ / Da” ₀ ".
[0033]
【The invention's effect】
According to the configuration of the first aspect, by transmitting or receiving the transmission target data and the bit-reversed data alternately, the transmission target data is transmitted after "11111111" or "00000000" in the worst condition. It is ensured that “00000000” or “11111111”, which is the bit inversion value of the target data, continues to prevent magnetic saturation of the pulse transformer.
Since the bit-inverted data of the transmission target data as described above can be easily generated by software processing by an operation for calculating a negative value of the data, magnetic saturation of the pulse transformer can be prevented at low cost by simple processing. Can be.
Moreover, on the receiving side of the serial data communication, the data to be transmitted is compared with the bit-reversed data, and if the corresponding digits are not bit-reversed values, the data is not properly transmitted / received, and It is possible to detect that a communication abnormality has occurred, and to contribute to improving the quality of data communication.
[0034]
According to the configuration of claim 2, one transmission target data is divided into a plurality of groups (including a case where the number of bits belonging to one group is 1 bit), and data of the group is considered. The actual transmission data is reconstructed from the transmission target data such that the data (bit inversion auxiliary data) constituted by the negative values of the bits of the group are alternately arranged.
Therefore, the original data and the bit inversion auxiliary data change in a short period, which makes it difficult for the pulse transformer to cause magnetic saturation, and alleviates the condition for the magnetic saturation of the pulse transformer. In this case, the smaller the number of bits in each group, the shorter the period of change between the original data and the bit-reversed auxiliary data, making the pulse transformer less likely to cause magnetic saturation.
Thus, magnetic saturation of the pulse transformer can be prevented at low cost by simple processing.
In addition, on the receiving side of the serial data communication, the original data (part of the transmission target data) and the bit-reversed auxiliary data are compared, and if the corresponding digits are not bit-reversed values, In addition, it is possible to detect that data is not properly transmitted / received and some communication abnormality has occurred, which can contribute to improvement of data communication quality.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a communication circuit according to a first embodiment and a second embodiment of the present invention. FIG. 2 is a signal explanatory diagram according to the first embodiment of the present invention. FIG. 3 is a first embodiment of the present invention. FIG. 4 is a signal explanatory diagram according to a second embodiment of the present invention.
CL communication line 13,23 pulse transformer

Claims (2)

A serial data communication method for transmitting or receiving transmission target data as serial data via a communication line provided with a pulse transformer,
Find bit-inverted data of the transmission target data,
A serial data communication method for alternately transmitting or receiving the transmission target data and the bit-reversed data for each data. A serial data communication method for transmitting or receiving transmission target data as serial data via a communication line provided with a pulse transformer,
Each bit of the transmission target data is divided into a plurality of groups, and the data of each group and the bit-reversed auxiliary data constituted by the negative value of each bit of the group are alternately arranged in a digit arrangement. To generate actual transmission data,
A serial data communication method for transmitting the actual transmission data to the communication line.

Images