JP3646594B2 - Communications system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication system, and more specifically to a system that realizes multi-baud rate communication in a wired communication system that is insulated on a transmission side and a reception side.
[0002]
[Prior art]
For example, in the case of FA communication, wired multi-baud rate communication is often used. That is, in the case of the multi-baud rate, the transmission speed can be changed, so that an efficient system can be obtained by selecting the transmission distance, the number of connected nodes, the response performance, etc. according to the application.
[0003]
It is necessary to insulate the communication line and the internal circuit in a DC manner in order to prevent damage caused by a loop current due to a ground potential difference or a surge voltage on the line. For this reason, normally, the transceiver and the communication control logic are insulated by using a photocoupler and an isolated DC-DC converter (or a communication dedicated power source).
[0004]
[Problems to be solved by the invention]
However, the above-described conventional insulation method has a problem of high cost. In other words, the isolated DC / DC converter itself is expensive, and a plurality of control lines are wired between the transceiver and the communication control logic, one for each of the control lines. This is because a photocoupler must be attached. Furthermore, attaching a photocoupler to each individual control line has a problem that the attached portion becomes large.
[0005]
An object of this invention is to provide the communication system which can implement | achieve wired multi-baud rate communication with a simple and cheap structure.
[0006]
[Means for Solving the Problems]
In the communication system according to the present invention, the transmission unit and the reception unit are connected to the transmission line via pulse transformers, respectively, and the transmission unit inserts an inverted code when the same data continues N times with respect to the baseband code. A first transmission function transmission processing unit for transmitting encoded data to be transmitted, and a second transmission function transmission processing unit for transmitting data obtained by SS encoding the baseband code. One of the transmission processing unit and the transmission processing unit of the second transmission function, and the reception unit encodes data from the transmission processing unit of the first transmission function of the transmission unit. Reception processing unit of the first transmission function that performs reception processing when receiving data, and reception of the second transmission function that performs reception processing when receiving encoded data from the transmission processing unit of the second transmission function of the transmission unit And a processing unit The first transmission function reception processing unit and the second transmission function reception processing unit are selectively selected. In the transmission unit and the reception unit, any one of the first transmission function and the second transmission function is selected. And performing data communication between the transmitting unit and the receiving unit using the same selected transmission function, and further, the respective transmission frequency bands of the first and second transmission functions are It was set to be approximately equal and within a range that can be handled by the pulse transformer.
[0007]
The baseband code is a code that is not subjected to modulation by converting an analog amount or code representing information into an electric signal as it is. For example, there are NRZI, mBIC, Manchester and the like. The encoding for realizing the first transmission function is 4B1C encoding in the embodiment, which inserts 1 inverted bit when 4 bits of continuous data follow. Of course, other encoding methods may be used.
[0008]
By using a pulse transformer, data can be transmitted and received in a state where the transmitter and the receiver are insulated. This pulse transformer also has the advantage of being inexpensive. By the way, in the case of an insulation method using a pulse transformer, it is difficult to widen the frequency band of the transformer, so that the transmission frequency cannot be changed greatly in order to realize multi-baud rate communication.
[0009]
Therefore, by performing SS encoding on the baseband code, the same effect as multi-baud rate communication can be achieved without greatly changing the actual transmission frequency. That is, in SS encoding, baseband code data “1” is expressed by a code consisting of an n-digit chip sequence, and the inverted chip sequence expresses data “0”. In this way, since it takes n digits, it takes time to send one piece of data, but it is resistant to disturbance noise and has communication distance, number of connected nodes, branches, etc., compared to those that transmit baseband codes. The spec is expanded. In the embodiment, SS11 chip coding is used. However, the present invention is not limited to this, and other SS coding may be used.
[0010]
In the chip sequence of the SS code, about 1 to several (M) identical chips may be continuous, so the actual transmission frequency band falls within the range of 1 to M times. Here, M is less than n and is usually about 3 to 4. On the other hand, the transmission frequency band in the first transmission function is in the range of 1 to N times. Therefore, if N = M, the transmission frequency bands of the first and second transmission functions are equal. Of course, in the present invention, since it is not necessary to match completely, a value that approximates N and M may be taken. Furthermore, if the transmission frequency band is about 1 to 4 times, it is within a range that can be sufficiently handled by a pulse transformer.
[0011]
That is, while the transmission frequency bands are substantially equal, high-speed transmission can be performed by communicating with the first transmission function, and long-distance transmission or the like can be performed by communicating with the second transmission function.
[0012]
Each function constituting the communication system according to the present invention can be realized by a dedicated hardware circuit, or can be realized by a programmed computer.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a preferred embodiment of a communication system according to the present invention. In the figure, for the sake of simplicity, an example is shown in which the transmission unit 10 and the reception unit 20 are connected one by one, but there are a plurality of one side or both sides of the transmission unit 10 and the reception unit 20. Of course, such a system is also acceptable.
[0014]
In this embodiment, for the NRZ data as the baseband code, as an encoding process for realizing a first transmission function for transmitting and receiving encoded data for inserting an inverted code when the same data continues N times, 4B1C encoding was used, and SS11 chip was encoded as SS encoding.
[0015]
In other words, the 4B1C encoder 11 and the SS11 chip encoder 12 are incorporated in the transmission unit 10, and one is selected via the switch S1. In addition, the receiving unit 20 includes a 4B1C decoder 21 and an SS11 chip decoder 22 corresponding to the transmitting unit 10, and selects one by switching the switch S2.
[0016]
The encoded data output from the transmission unit 10 is given to the primary side of the pulse transformer 32 via the communication transceiver 31 and sent out via the transmission path 35 connected to the secondary side of the pulse transformer 32. The
[0017]
On the other hand, a receiving-side pulse transformer 33 is connected to the other end of the transmission path 35, receives encoded data transmitted from the transmission unit 10 via the transmission path (wired) 35, and passes through the communication transceiver 34. The data is taken into the receiving unit 20.
[0018]
Thus, by connecting both the switches S1 and S2 to the contact a, when transmitting certain data, the data encoded using the 4B1C encoder circuit 11 is transmitted, via the pulse transformers 32 and 33 and the transmission path 35. Then, the data received by the receiving unit 20 is decoded by the 4B1C decoder circuit 21. When the switches S1 and S2 are set to b contact, SS11 chip-encoded data is transmitted. Therefore, the communication lines (transmission path 35 and the like) and the internal circuits (transceivers 31 and 34, the communication unit 10 and the reception unit 20 and the like) are insulated from each other by the pulse transformers 32 and 33, and wired (transmission path 35) ) Communication.
[0019]
Note that switching of the switches S1 and S2 is usually performed when each device is installed, which encoding transmission is determined according to the installation status, communication environment and specifications, and is set at one of the contacts. I have to. That is, after installation, the switches S1 and S2 are not switched, but the switches S1 and S2 may be switched at an arbitrary timing by transmitting and receiving a switching control signal or the like.
[0020]
The specific internal structure of the communication unit 10 is as shown in FIG. 2, and the internal structure of the reception unit 20 is as shown in FIG. First, as shown in FIG. 2, it has a transmission timing generation circuit 14 that temporarily receives NRZ data (SNDDATA) to be transmitted and outputs it at a predetermined timing.
[0021]
The transmission timing generation circuit 14 synchronizes with the transmission clock (SNDCLK) generated by the CLK generation circuit 13 in a state where SNDEN is ON, and receives the NRZ data (SDLTD) to be transmitted once received by the 4B1C encoder circuit 11. Alternatively, the signal is supplied to the SS11 chip encoder circuit 12. Further, an ENCEN signal for permitting execution of the encoding process is sent to the encoder circuits 11 and 12.
[0022]
Each of the encoder circuits 11 and 12 receives the original signal data (SDLTD) to be transmitted and the ENCEN signal from the transmission timing generation circuit 14 and is also given a transmission clock (SNDCLK) generated by the CLK generation circuit 13. Thereby, when ENCEN is ON, the received original signal data is encoded in synchronization with the transmission clock, and the obtained encoded data (SND) is transmitted.
[0023]
For selection of which encoder circuit 11 or 12 is used, for example, an analog switch or the like is provided between the transmission timing generation circuit 14 and both encoder circuits 11 and 12, and the original signal data to be transmitted is sent to one of the encoder circuits 11 and 12. The encoder signal may be sent only to the encoder circuit, or the original signal data is sent to both the encoder circuits 11 and 12, and ENCEN is sent to only one encoder circuit to selectively select the encoder circuit that actually performs the encoding operation. Various other methods can be adopted.
[0024]
The above processing units 11, 13, and 14 constitute a first transmission function (transmission side) for transmitting and receiving 4B1C encoded data, and the processing units 12, 13, and 14 are SS11 chip encoded. A second transmission function (transmission side) for transmitting and receiving data. In addition, since each function of each process part 11-14 is well-known separately, concrete description is abbreviate | omitted.
[0025]
Next, each encoding method will be described. First, the 4B1C code used by this embodiment in the clock extraction method is an edge for clock synchronization at least once every 4 bits by inserting 1 inversion bit when 4 consecutive bits of data follow. Is to occur. Therefore, the 4B1C encoding circuit 11 monitors the given original signal data (NRZ), and normally outputs the received data as it is. When the same data (0 or 1) is received four times in succession, the inverted data A process of inserting (1 or 0) is performed.
[0026]
An example is shown in FIG. As shown in the figure, since the code (data) of NRZ is “1” five times consecutively, the 4B1C code outputs “1” four times consecutively, and then inserts one bit of the code to be inverted. To do. The inverted data is also inserted when the subsequent “0” continues four times.
[0027]
As is clear from the figure, the minimum pulse width is one chip (1 bit) and the maximum pulse width is four chips (4 bits). Therefore, the transmission frequency band is in the range of 1 to 4 times.
[0028]
On the other hand, as shown in FIG. 4B, the code of the SS11 chip (Barker series 11 chip) represents the NRZ data “1” as “11100010010” and the data “0” as its inverted “00011101101”. ing. As is clear from the figure, the minimum pulse width is 1 chip and the maximum pulse width is 4 chips.
[0029]
Therefore, when this SS encoding is performed, it is understood that the transmission frequency band is in the range of 1 to 4 times, which is the same range as that of 4B1C described above. Thus, for example, if the transmission rate at the time of 4B1C coding is 11 Mbps while the transmission frequency band is the same, the transmission rate at the time of SS coding is 1/11 and becomes 1 Mbps.
[0030]
Therefore, 4B1C code is used for high-speed transmission, and when long distance and multiple nodes are desired, the transmission frequency band can be made the same range by using the SS code system, and low-cost pulse transformer insulation is used. Thus, the same effect as the multi-baud rate can be obtained.
[0031]
On the other hand, as shown in FIG. 3, the receiving unit 20 receives the encoded data RCV received via the pulse transformer 33 and the communication transceiver 34 in the receiving unit 20, and the RCV is 4B1C encoded data. In this case, the signal is supplied to the edge detection circuit 23 and the 4B1C decoder circuit 21.
[0032]
The edge detection circuit 23 detects the edge of the encoded data (rising / falling edge of the pulse), and outputs a synchronization signal (SYNF) in bit units when the edge is detected. Also, a synchronization confirmation signal (LOCK) and a synchronization flag count value (SYNCCNT) are output. These three signals are supplied to the 4B1C decoder circuit 21, and the synchronization position signal (SYNF signal) is also supplied to the DPLL circuit 24.
[0033]
The DPLL circuit 24 outputs a synchronized chip sampling clock (DPLLCLK) from the synchronization position signal and supplies it to the 4B1C decoder circuit 21. The 4B1C decoder circuit 21 detects the inserted bit portion shown in FIG. 4A based on the given signal, and removes (decodes) the inserted bit portion to generate original signal data as NRZ received data. Output (RCVDATA). Each of the processing units 21, 23, 24 described above constitutes a first transmission function (receiving side) for transmitting / receiving 4B1C encoded data.
[0034]
On the other hand, when the received encoded data RCV is SS11 chip encoded data, the received data RCV is given to the matched filter circuit 25, where correlation calculation is performed, and the calculation result is expressed as a correlation value ( Output as MATCHVAL). This correlation value is given to the bit synchronization determination circuit 26 and the SS11 chip decoder circuit 22.
[0035]
The bit synchronization determination circuit 26 outputs a bit-by-bit synchronization position signal (SYNF) from the given correlation value. Further, a synchronization confirmation signal (LOCK) and a synchronization flag count value are output, and these three signals are given to the SS11 chip decoder circuit 22.
[0036]
The chip synchronous clock 6-stage DPLL circuit 27 outputs a synchronized chip sampling clock (DPLLCLK) based on the synchronization position signal (SYNF) received from the bit synchronization determination circuit 26, and the SS11 chip decoder circuit 22 To give.
[0037]
Then, the SS11 chip decoder circuit 22 determines the data from the correlation value (“1” or “0”) and outputs the data as NRZ reception data (RCVDATA). Each above-mentioned processing part 22,25-27 comprises the 2nd transmission function (reception side) for transmitting / receiving the data by which SS11 chip encoding was carried out. In addition, since each function of each process part 21-27 is well-known separately, concrete description is abbreviate | omitted.
[0038]
【The invention's effect】
As described above, according to the present invention, since the transmission unit and the reception unit are connected to the transmission line (line) via the pulse transformer, DC insulation can be realized with a simple configuration at low cost. Then, by flowing SS-encoded data on the transmission path, the baseband code is compared with data of an encoding method (first transmission function) in which an inverted code is inserted when the same data continues N times. The band can be made substantially the same, and a pulse transformer having a narrow frequency band can be used. Therefore, the first transmission function is used for high-speed communication, and the second transmission function based on the SS code is used for long-distance transmission or the like (communication speed: the transmission rate is slow). Communication can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a preferred embodiment of a communication system according to the present invention.
FIG. 2 is a diagram illustrating an example of an internal structure of a transmission unit.
FIG. 3 is a diagram illustrating an example of an internal structure of a receiving unit.
FIG. 4 is a diagram for describing encoding used in the present embodiment.
[Explanation of symbols]
10 Transmitter 11 4B1C Encoder Circuit 12 SS11 Chip Encoder Circuit 20 Receiver 21 4B1C Decoder Circuit 22 SS11 Decoder Circuit

Claims (1)

Connect the transmitter and receiver to the transmission line via pulse transformers, respectively.
The transmission unit includes a transmission processing unit of a first transmission function that transmits encoded data that inserts an inverted code when the same data is consecutive N times with respect to the baseband code, and the baseband code is an SS code. A transmission processing unit for the second transmission function that transmits the converted data, and alternatively selects one of the transmission processing unit for the first transmission function and the transmission processing unit for the second transmission function. ,
The reception unit receives a first transmission function when the encoded data is received from the transmission processing unit of the first transmission function of the transmission unit, and the second transmission function of the transmission unit. A second transmission function reception processing unit that performs reception processing when encoded data is received from the transmission processing unit of the first transmission function, and any of the first transmission function reception processing unit and the second transmission function reception processing unit. Or alternatively,
The transmitter and the receiver select either the first or second transmission function, and perform data communication between the transmitter and the receiver using the same selected transmission function.
Further, the communication system is characterized in that the transmission frequency bands of the first and second transmission functions are substantially equal and set within a range that can be handled by the pulse transformer.

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