JPH06296188A - Modem - Google Patents

Abstract

PURPOSE:To connect terminal equipments whose code form differs from each other while suppressing cost increase in the hardware by matching codes both of a signal outputted from the terminal equipment and of the terminal equipment being a communication destination depending on the code form of the signals. CONSTITUTION:The MODEM is provided with a communication line 1 comprising a public line or the like, a conventional MODEM 2, a terminal equipment 3 making communication with an NRZI code form, and a communication cable 4 adopting the RS232C form connecting them, and also a MODEM 5 with a code conversion function connecting to the communication line 1, a terminal equipment 6 making communication in the NRZ code system, and a communication cable 7 adopting the RS232C form interconnecting the terminal equipment 6 to the MODEM 5 with a code conversion function. Then the codes are matched in response to a code form of the signals, outputted from the terminal equipments 3,6 and a code form of the terminal equipments 3, 6 being communication destinations via the communication line 1 by a function converting the code system of the signals inputted/outputted to/from the terminal equipments 3, 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem device having a function of converting codes of different formats from each other.

[0002]

2. Description of the Related Art Conventionally, when communicating between terminal devices having different code formats, one of the terminal devices has often been modified to match the code format.

For example, one terminal device communicates with an external device by the NRZI code system, and the other terminal device communicates with the N device.
When communicating with an external device using the RZ code system,
Either one of these terminal devices, for example, a terminal device that communicates with an external device by the NRZI coding system converts the signal coding format from the NRZI coding system to the NRZ coding system or from the NRZ coding system to the NRZI coding system. An interface circuit for conversion is provided, and the format of the signal input to and output from this terminal device is the NRZ code system, which enables communication between the terminal devices.

[0004]

However, in such a method, when the modified terminal device is connected to another terminal device, the modified contents must be restored or further modified. In order to eliminate such inconvenience, in recent years, it has been considered to insert a code converter between each of these terminal devices and enable communication between each terminal device by matching the code format by this code converter. .

FIG. 7 is a block diagram showing an example of a communication system using such a code converter.

The communication system shown in this drawing is of a terminal device 101 which communicates by the NRZI code system, a terminal device 102 which communicates by the NRZ code system, and an RS232C format which connects these terminal devices 101, 102. The communication cable 103 and the code converter 104 that is inserted in the middle of the communication cable 103 and converts the code formats of the signals output from the terminal devices 101 and 102 to each other are provided. When a signal is output from the terminal device 102, the code converter 104 converts the code format of the signal from the NRZI code system to the NRZ code system and transmits the signal to the other terminal device 102, and the other terminal device 102 outputs the signal. At this time, the code converter 104 converts the code format of this signal from the NRZ code system to the NRZI code system. Transmitted to the terminal device 101, to support communication between each of these terminals 101 and 102.

In this case, the code converter 104 is loaded by the two RS232C interface circuits 105 and 106 to which the connector of the RS232C format communication cable 103 is connected as shown in FIG. 8 and the RS232C interface circuits 105 and 106. And a processor circuit 107 having a code conversion function for mutually converting the formats of the generated signals.

Then, the NRZ from one terminal device 101
A signal of the I code system is output, and this is one RS232
When input via the C format communication cable 103,
One RS2 connected to this communication cable 103
This is taken in by the 32C interface circuit 105, and the RS232 is taken by the processor circuit 107.
After converting the code format of the signal taken in by the C interface circuit 105 from the NRZI code system to the NRZ code system, the other RS232C interface circuit 10
This is taken in by 6 and the other RS232
The other terminal device 1 via the C-type communication cable 103
Output to 02.

A signal of the NRZ code system is output from the other terminal device 102, and this is the other communication cable 1
This communication cable 103 when input via 03
This is taken in by the other RS232C interface circuit 106 connected to the RS232C interface circuit 106, and the RS232C interface circuit 1 is taken in by the processor circuit 107.
After converting the code format of the signal taken in by 06 from the NRZ code system to the NRZI code system, one of the RS2
The 32C interface circuit 105 captures this and outputs it to one terminal device 101 via one communication cable 103.

By the way, when the terminal devices 101 and 102 having different code formats are connected to each other via the communication cable 103 as described above, the communication system described above can be sufficiently dealt with, but in recent years, they are mutually coded. There is a demand to configure a communication system by connecting terminal devices 101 and 102 having different formats via a public line.

FIG. 9 is a block diagram showing an example of a communication system capable of satisfying such a demand by using the code converter 104 shown in FIG.

The communication system shown in this figure includes a communication line 110 composed of a public line and the like, and a communication line 1
Two modem devices 111, 112 connected to
Terminal device 113 that communicates by the NRZI code system
And a communication cable 114 of RS232C format for connecting the terminal device 113 and the modem device 111 on one side,
A terminal device 115 that communicates using the RZ code system, and an RS that connects the terminal device 115 and the other modem device 112.
A communication cable 116 of 232C format and a code converter 104 for mutually converting the code format of a signal inserted in the communication cable 116 and input / output to / from the other terminal device 115.
It has and.

Then, from one of the terminal devices 113, the NRZ
When a signal of the I code system is output, it is taken in by one of the modem devices 111, and a transmission signal is generated by being packetized or modulated, and this is transmitted via the communication line 110 to the other modem device 112. Is supplied to the modem device 112 and then demodulated by the modem device 112, and the code format of the signal is N by the code converter 104.
The RZI code system is converted to the NRZ code system, and this is supplied to the other terminal device 115.

When a signal of the NRZ code system is output from the other terminal device 115, the code format of this signal is changed from the NRZ code system to NRZI by the code converter 104.
It is converted into a code system and the other modem device 11
2 is packetized or modulated to generate a transmission signal, which is supplied to one modem device 111 via the communication line 110, and then this modem device 11
It is demodulated by 1 and supplied to one terminal device 113.

In this case, the modem device 112 is connected to the communication line 110 as shown in FIG.
Modem circuit 120 for modulating / demodulating a signal input / output to / from 0
And an RS232C interface circuit 121 that is connected to the RS232C format communication cable 116 and that inputs and outputs signals to and from this communication cable 116, and this RS
The signal output from the 232C interface circuit 121 is subjected to error correction processing, data compression processing, packetization processing, etc., and supplied to the modem circuit 120, and data error correction processing of the signal output from the modem circuit 120 is performed. RS232 by performing processing such as data decompression processing
And a processor circuit 122 for supplying the C interface circuit 121.

When a signal is output from the code converter 104, the RS232C interface circuit 121 captures the signal and converts it into data, and the processor circuit 122 captures the data and performs error correction processing and data compression processing. After being subjected to processing such as packetization processing, the data is serialized by the modem circuit 120, modulated and converted into a transmission signal, which is transmitted to the other modem device 111 via the communication line 110. It

When a transmission signal is output from the other modem device 111 and input through the communication line 110, the modem circuit 120 captures and demodulates the transmission signal, and then the processor circuit 122 expands the data. While being processed, the RS232C interface circuit 121 captures this and supplies it to the code converter 104.

By the way, since such a code converter 104 has not been developed yet, when the communication system shown in FIG. 7 is constructed, the development of the code converter 104 requires a large amount of development cost.

Further, when constructing the communication system shown in FIG. 9, since two modem devices 111 and 112 are required together with such a code converter 104, the number of parts becomes too large, and the number of hardware components is increased. There was a problem that the cost became too high.

In view of the above circumstances, the present invention provides a terminal device having a code format different from each other via a communication line such as a public line while suppressing an increase in hardware cost by a development cost similar to that of a code converter. It is an object to provide a modem device that can be connected.

[0021]

In order to achieve the above-mentioned object, the present invention provides a connection between a communication line and a terminal device.
As a result, in the modem device that supports the communication between the communication line and the terminal device, the modem device has a function of converting the coding method of the signal input / output to / from the terminal device, and the code of the signal output from the terminal device. It is characterized in that these codes are matched according to the format and the code format of the terminal device which is a communication destination via the communication line.

[0022]

In the above structure, the function of converting the coding system of the signal input / output to / from the terminal device allows the terminal to be a communication destination via the communication line and the code format of the signal output from the terminal device. By matching these codes according to the code format of the device, while suppressing the hardware cost increase by the development cost equivalent to the development of the code converter, the code formats are mutually transmitted via the communication line such as the public line. Connect different terminal devices.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, prior to a detailed description of the present invention, the basic principle of a modem device according to the present invention will be described.

First of all, a modem device in recent years is called an intelligent modem device, and a microprocessor is installed inside the modem device so that a communication speed with a terminal device can be obtained regardless of error correction processing, data compression processing, and communication speed between lines. It is common to have advanced processing functions such as the function to keep the constant.

Therefore, in the modem device according to the present invention, as shown in FIG. 6, a portion where the modem device 112 and the code converter 104 used in a communication system and the like overlap (a part surrounded by a dotted line), that is, the modem device 112 side is provided. RS232
The C interface circuit 121 and the RS232C interface circuit 105 and the processor circuit 107 on the side of the code converter 104 are eliminated, and the processor circuit 122 on the side of the modem device 112 is provided with a code conversion function. Without developing
Terminal devices 11 having different code formats from each other via a public line
3,115 can be connected.

FIG. 1 is a block diagram showing an example of a communication system to which an embodiment of the modem device according to the present invention based on the above-mentioned basic principle is applied.

The communication system shown in this figure includes a communication line 1 formed of a public line, a normal modem device 2 connected to the communication line 1, a terminal device 3 for communicating by the NRZI code system, A communication cable 4 of RS232C format for connecting the terminal device 3 and one of the modem devices 2, a modem device 5 with a code conversion function connected to the communication line 1, and a terminal device 6 for communicating in the NRZ code system.
And an RS232C type communication cable 7 for connecting the terminal device 6 and the modem device 5 with a code conversion function.

In this communication system, when a signal of the NRZI coding system is output from one terminal device 3, the modem device 2 captures the signal and packetizes or modulates the transmitted signal. It is generated and supplied to the modem device 5 with a code conversion function through the communication line 1 and then demodulated by the modem device 5 with a code conversion function, and the code format of the signal is NRZ.
The I code system is converted to the NRZ code system, and this is supplied to the other terminal device 6.

Further, in this communication system, when a signal of the NRZ code system is output from the other terminal device 6, the code format of this signal is converted from the NRZ code system to the NRZI code system by the modem device 5 with a code conversion function. At the same time, the transmission signal is generated by packetizing or modulating it, and this is transmitted via the communication line 1 to one modem device 2
To the terminal device 3 on the one hand.

The modem device 5 with a code conversion function is connected to the communication line 1 as shown in FIG. 2, and the modem circuit 8 for modulating / demodulating the signal input / output to / from the communication line 1 and the RS 23.
An RS232C interface circuit 9 connected to the 2C format communication cable 7 for inputting / outputting a signal to / from the communication cable 7, a code conversion process, an error correction process, a data compression process of a signal output from the RS232C interface circuit 9, The modem circuit 8 is subjected to processing such as packetization processing and supplied to the modem circuit 8.
The RS232C performs processing such as code conversion processing, data error correction processing, and data decompression processing of the signal output from the RS232C.
The processor circuit 10 is supplied to the interface circuit 9.

When the signal is output from the other terminal device 6, this modem device 5 with a code conversion function is R
The S232C interface circuit 9 fetches the data and converts it into data, and the processor circuit 10 fetches the data to change the NRZ coding method to NR.
After performing code conversion into the ZI code system and further performing error correction processing, data compression processing, packetization processing, etc.,
The data is serialized by the modem circuit 8, modulated and converted into a transmission signal, which is transmitted to the normal modem device 2 via the communication line 1.

Further, this modem device 5 with a code conversion function
When a transmission signal is output from the modem device 2 and is input via the communication line 1, the modem circuit 8 of the modem device 5 with a code conversion function captures the signal and demodulates it, and then the processor circuit 10 decodes the NRZI code. The code is converted from the system to the NRZ code system, data decompression processing is further performed, and the RS232C interface circuit 9 captures the data and supplies it to the other terminal device 6.

In this case, the modem device 5 with a code conversion function
The following algorithm is used as the code conversion algorithm of.

First, as shown in FIG. 3, the binary number is "1".
When expressing 001101 ", in the NRZ coding system,
Since the logic "1" is represented by the code "1" and the logic "0" is represented by the code "0", the binary number "100110"
If "1" is expressed by the NRZ code system, "100110"
In the NRZI code system, the code is inverted every logical "0", so that the binary number "100110" is used.
If "1" is expressed by the NRZI code system, "101110"
It becomes 0 ".

When converting the NRZI code to the NRZ code, "11" .fwdarw. "1", "10" .fwdarw. "0", "0" depending on the relationship between the bit to be converted and the previous bit.
Codes are assigned as 0 ”→“ 1 ”and“ 01 ”→“ 0 ”.

As a result, when the logic of the NRZI code to be converted is "1011100", it is assumed that the bit before the first bit is logic "1", and as shown in FIG. NRZ code “10” after processing
01101 ″ is generated.

When converting an NRZ code to an NRZI code, an inverted code is assigned each time the bit to be converted becomes a logical "0".

With this, when the logic of the NRZ code to be converted is "1001101", the NRZI code "1011100" is generated by sequentially processing from the first bit.

As described above, in this embodiment, the function of converting the NRZI code into the NRZ code by the processor circuit 10 provided inside the modem device 5 with the code conversion function and the function of converting the NRZ code into the NRZI code are provided. Since the cost of the hardware is suppressed by the development cost equivalent to the development of the code converter 104, the terminal devices 3 having different code formats from each other through the communication line 1 such as a public line, 6 can be connected.

Further, in this embodiment, an algorithm for converting an NRZI code into an NRZ code and the NR
Since the algorithm for converting the Z code to the NRZI code is simplified, it is possible to reduce the load on the microprocessor constituting the processor circuit 10 and reduce the overhead due to the code conversion.

FIG. 5 is a block diagram showing another embodiment of the modem device according to the present invention.

A modem device 5b with a code conversion function shown in this figure is connected to a communication line 1 and a modem circuit 8b for modulating / demodulating a signal input / output to / from the communication line 1 and an RS2.
An RS232C interface circuit 9b having a code switching function, which is connected to the 32C format communication cable 7 and inputs / outputs signals to / from the communication cable 7, and the RS23
It controls the 2C interface circuit 9b and the modem circuit 8b, performs processing such as processing of signals output from the RS232C interface circuit 9b, error correction processing, data compression processing, and packetization processing, and supplies them to the modem circuit 8b. And a processor circuit 10b which performs processing such as data error correction processing and data decompression processing of the signal output from the modem circuit 8b and supplies it to the RS232C interface circuit 9b.

Prior to the communication process, the RS232C interface circuit 9b has the RS232C interface circuit 9b which controls the processor circuit 10b according to the code format of another terminal device 6 to which the modem device 5b with a code conversion function is connected. Either the NRZ function 15 or the NRZI function 16 is selected.

When a signal is output from the other terminal device 6, RS2 of the modem device 5b with a code conversion function is output.
This is taken in by the 32C interface circuit 9b, code conversion is performed, and data is generated. At the same time, after the data is taken in by the processor circuit 10b and subjected to processing such as error correction processing, data compression processing, and packetization processing, the data is serialized and modulated by the modem circuit 8b, and is transmitted. Is converted into the normal modem device 2 via the communication line 1.

When a transmission signal is output from the modem device 2 and is input via the communication line 1, the modem circuit 8b of the modem device 5b with a code conversion function captures and demodulates it, and then the processor Circuit 1
0b performs data decompression processing and the like, and after the RS232C interface circuit 9b fetches the data, code conversion is performed and the other terminal device 6
Is supplied to.

As described above, in this embodiment, the RS232C interface circuit 9b is constructed by using the elements having the NRZ function 15 and the NRZI function 16 which have already been developed, and the RS232C interface circuit 9b is formed by the processor circuit 10b.
Since either the NRZ function 15 or the NRZI function 16 of the 232C interface circuit 9b is selected and used, the code converter 104 is developed in the same manner as the above-described embodiment without burdening the processor circuit 10b. It is possible to connect the terminal devices 3 and 6 having different code formats to each other via the communication line 1 such as a public line while suppressing the increase of the hardware cost by the development cost of the same level.

[0047]

As described above, according to the present invention, the code format is mutually changed via the communication line such as the public line while suppressing the increase of the hardware cost due to the development cost equivalent to the development of the code converter. Different terminal devices can be connected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a communication system using an embodiment of a modem device according to the present invention.

FIG. 2 is a block diagram showing a detailed circuit configuration example of the modem device shown in FIG.

3 is a schematic diagram showing an example of a relationship between an NRZ code and an NRZI code converted by the modem device shown in FIG.

4 is a schematic diagram showing an example of a conversion operation of the modem device shown in FIG.

FIG. 5 is a block diagram showing another embodiment of the modem device according to the present invention.

FIG. 6 is a block diagram for explaining the basic principle of the modem device according to the present invention.

FIG. 7 is a block diagram showing an example of a communication system that can be considered when connecting terminal devices having different code formats from each other.

8 is a block diagram showing an example of a circuit considered as a specific circuit configuration example of the code converter shown in FIG.

FIG. 9 is a block diagram showing an example of a communication system that can be considered when connecting terminal devices having different code formats from each other via a public line.

10 is a block diagram showing a detailed circuit configuration example of the modem device shown in FIG. 9. FIG.

[Explanation of symbols]

 1 Communication Line 2 Normal Modem Device 3 Terminal Device 4 RS232C Type Communication Cable 5 Modem Device 6 Terminal Device 7 RS232C Type Communication Cable 8 Modem Circuit 9 RS232C Interface Circuit 10 Processor Circuit

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Claims (1)

[Claims] 1. A connection between a communication line and a terminal device,
In a modem device that supports communication between a communication line and a terminal device, the modem device has a function of converting a code system of a signal input to and output from the terminal device, and a code format of a signal output from the terminal device. A modem device characterized by matching these codes according to a code format of a terminal device which is a communication destination via a communication line.