JPS63171039A - Data transmission system - Google Patents

Abstract

PURPOSE:To avoid waiting of command frame transmission due to data frame transmission by transmitting a command frame in a signal to a control line and transmitting a data frame and an information frame in the signal to an information line. CONSTITUTION:In accordance with the command frame which passes a control line 107, a CPU 113 of a host equipment 101 and a CPU 119 of a data terminal 102 determine the information line to be used for data transmission and transmit and receive connection information to and from a terminal of the other party of an external telephone network through a trunk line 103. If the CPU 112 of the terminal 102 has data to be transmitted, the host equipment 101 receives the data frame from the terminal 102 through information lines 104-106, a cross point 111, and an interface unit IFU 112. The CPU 113 transmits the transmission frame from the IFU 112 to the data terminal of the other party from a switch 115 through the trunk line 103. similarly, data from the data terminal of the other party is received by the CPU 113, and data from the CPU 113 is received by the CPU 119 through information lines 104-106 and an IFU 118.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a data transmission system.

(Prior Art) In recent years, advances in information technology have spread to the home, and networking within the home is rapidly progressing.

In the home, electrical appliances such as televisions and air conditioners, communication devices such as telephones and facsimiles, and information devices such as personal computers are in conflict with each other, and a network that organically connects these devices can be considered.

The main device 1 that controls the network in the home (hereinafter referred to as the home), whose configuration diagram is shown in FIG. 2, is connected to an external subscriber telephone network via a central office line 2.3. Two types of cables, an information line 4 and a control line 5, are connected to the inside of the house.

There may be a plurality of information lines 4, and devices in the home use them to perform voice communication and data communication with an external telephone network. The control line 5 is commonly used by devices in the house and communicates control information between each device and between the main device 1 and the devices. Connect various devices in your home to these information lines 4 and control lines 5 to information outlets 6.8.10.12.14.16
It connects and creates a network. There are some household devices that use both the information line 4 and the control line 5, and some that use only the control line 5.

A telephone terminal 7, an information terminal such as a personal computer 9, and a facsimile 10 are connected to the information outlet 6.8.10, and these use the information line 4 and the control 11L5 for information communication. Information outlets 12, 14, and 16 have sensors 13 for detecting disasters, gas, etc., and ON 1 for air conditioners, electric lights, etc.
Control unit 15 such as 0 F F, sub controller 1
7 is connected.

The above-mentioned sensor 13, a sensor 18 similar to the control unit 15, and a control unit 19 are connected under the sub-controller 17, and the sub-controller 17 represents these control information and communicates via the control line 5. I can do it.

In such a home network system configuration,
Since control line 5 is commonly used by all devices, physical (
Standards have also been standardized for hardware, frame formats, and procedures (lift).

FIG. 3 is a block diagram of an interface unit for connecting to the control line 5. In the figure, an interface unit (hereinafter referred to as IFU) 22 is connected to a bare control line 5 via an information outlet 21. code 23
is a transformer, to which a transmitting circuit 24 and a receiving circuit 25 are connected.

The transmitting circuit 24 transmits frames to the control line 5, and frame transmission data is transferred from the CPU 26. The receiving circuit 25 sends the data on the Mtn line 5 to the CPU.
Transfer to 26. Since the data transmitted by the transmitting circuit 24 is also looped back to the receiving circuit 25, the CPU 26 can monitor and receive the frame transmitted by itself, and thereby can detect if there is a collision with the frame transmitted by another device. . Since the transmission timing of the frame is determined, the CPU 26 controls the transmission to be stopped and retransmitted at the next transmission timing when transmission data collides. i of
It sends and receives frames and exchanges control information with devices, main devices, etc. This frame data is interfaced to the CPU of the host computer via the connector 27.

FIG. 4 illustrates the configuration of the main device 1 and the data terminal in more detail. The main device 1 has three information lines 4a,
4b and 4c are connected to a control line 5, and a data terminal 29 is connected to this control line 5 via an information outlet 28.

Next, the configuration of the main device 1 will be explained. The cross point 31 is an analog switch that connects/disconnects the office line 3 and the information lines 4a, 4b, and 4c. The interface unit (IFU) 22a having the above-described configuration transmits and receives frames on the control line 5, and the CPU 32 controls each connected device by switching the cross point 31 and transmitting frames by the IFU 22a. A modem 33 performs data transmission with a center device such as a partner data terminal or computer connected via an external network. A switch 34 connects the modem 33 and the central office line 3.

By having the modem 33 in the main device 1, the data terminal inside the home becomes an economical system that does not require a built-in modem.

Next, the configuration of the data terminal 29 will be explained. The IFU 22b transmits and receives frames on the control line.

The CPU 35 determines the frame contents in the IFU 22b and controls the display 36, floppy disk 37, etc. The CPU 35 is the main CPU of a personal computer or the like. Information outlet 28 connects control line 5 and data terminal 29
Connect with.

Next, the operation when the data terminal 29 communicates with a partner data terminal via an external network will be described.

In control a5, a command frame for specifying connection to or disconnection from the office line 3, a telephone number of the other party to an external network, etc., and a frame for data transmission after connection to the external network are commonly present.

First, the CPU 35 of the data terminal 29 uses the IFIJ 22b
A command frame requesting connection to an external network is transmitted to the IFU 22a of the main device 1 via the control line 5.

The CPU 32 of the main device 1, which received the command frame of this connection request, connects the data terminal 29 to the data terminal 2 if the central office line 3 is not in use.
IFU2 sends a command frame that allows dialing to
2a to the data terminal 29 via the control li5. The CPU 35 of the data terminal 29 sends a command frame specifying the telephone number of the other party's data terminal to the IFU 22.
b to control line 5. The CPU 32 of one unit v1 is
Using this telephone number, the other party's data terminal is called, and when the connection is completed, a connection completion command frame indicating that connection is transmitted to the data terminal 29. Also, the CPU 32 of the main device 1
At the same time, switch 34 is turned on to connect modem 33 to office line 3.

Upon receiving the connection completion command frame from the main device 1, the data terminal 29 transfers the data frame to the IF.
Transmitted from U22b. This data frame is received by the main device 1 through the control line 5, and the CPU 32 of the main device 1
transmits the data of this data frame to the central office line 3 via the modem 33.

When a data terminal connected via an external network transmits data, the modem 33 of one unit gL1 receives this data and sends it to the control line 5 via the IFU 22a to the data terminal '29. Send as a data frame. As a result, the CPU 35 of the data terminal 29 uses the IFU2
Receive data from 2b.

FIG. 5 shows the frame format of the control line 5. Figure 5 (a
) is the basic format of the frame, as shown in Figure 5(b).
indicates the bit format of the character format.

As shown in FIG. 5(a), one frame includes a character 41 indicating the priority of the frame, a self-address 42 indicating the device that sent the frame, a destination address 43 to which the frame should be received, the command type of the frame, the number of retransmissions, etc. a control code 44, a message length code 45 indicating the number of characters of subsequent data, etc., a data and command area 46 whose length is determined by the message length code 45, a check code 47 for detecting frame transmission errors, and an error check. Dummy character 4 to save calculation time
8. ACK/NAK for frame error control
It consists of a code area 49. By taking a certain period of pause after one frame, this is used to detect the frame processing time during reception and the beginning position of the next frame.

Each code in the frame is composed of asynchronous characters, and FIG. 5(b) shows its bit format. In the figure, each character consists of one start bit (ST) and one stop bit (SP). bit,
Parity bit (P) 1 bit, data (Do~D7)
8-bit format % expression % $1911 The device connected to line 5 uses the frame shown in FIG. 5 to exchange necessary commands to i!
The data and command area 46 in the frame of FIG. 5 is used as a command area to control each device, but it is also possible to carry information (data) between devices. It is.

Generally, there are 1 command to control each device.
Characters are several characters in length, and data is characterized by a length of several hundred to ~256 characters (maximum length in this example).

Here, if the transmission speed of the control line 5 is 9600 bits/second and the pause period is 10 Ils, the transmission times of a command frame with a 1-character command and a data frame with 256 characters of data are as follows. . In addition, each code other than data is all one character (
11 bits).

Command frame transmission time = 11x (8+ 1)x
1/9600+ 1On+s+ 20.3Ils Data frame transmission time = 11x (8+ 256)X
1/9600 + 1011S = 312.5113 Based on this frame transmission time, if only command frames are sent and received, each device can exchange control commands approximately every 20ns, but by allowing data frames on the control line, up to 300Ils etc. Frame transmission from these devices will have to wait. This poses a major problem in equipment systems that require real-time control.

To this end, the following countermeasures can be considered: 1) Make data frames lower in priority than command frames.

■Control so that a command frame can be inserted and sent even in the middle of a data frame.

Methods (2) and (2) are also effective if a data frame and a command frame occur at the same time in (2), but they are probabilistic. There is a problem that the processing load becomes heavy and the efficiency of data transmission decreases.

(Problems to be Solved by the Invention) As described above, in the conventional data transmission system, when a data frame is placed in a device system that requires real-time control, the sending of a time command frame that occupies a transmission path is made to wait. Since this is a major problem, countermeasures such as prioritizing frames or interrupting frames can be considered.

However, when prioritizing frames,
This is effective only for frames that occur simultaneously, and when interrupting frames, there is a problem that the load on the CPU increases and data transmission efficiency decreases.

The present invention has been made to solve these problems, and an object of the present invention is to provide a data transmission system that can eliminate the need to wait for transmission of command frames without reducing data transmission efficiency.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides a main device capable of transmitting and receiving frames and a plurality of data terminals connected via a control line and an information line. In a data transmission system in which signals are sent and received to and from a data terminal, a command frame in the signal is sent to the control line, and a data frame in the signal is sent to the information line. It is characterized by

(Function) Between the main device and the data terminal, command frames are transmitted via a control line, and data frames are transmitted via an information line. Therefore, it is possible to avoid waiting for the transmission of a command frame due to the transmission of a data frame, and in this case, it does not impose a large burden on the control side.
It does not reduce the efficiency of data transmission.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the system configuration of the present invention.

In this embodiment, there is only one subscriber telephone office line for connecting to an external network.
The system has four wires inside the house. 4 inside the house
The book line has three information lines and the remaining one line is used as a control line.

In the figure, a main device 101 connects devices inside the home to an external network and controls each device inside the home.

The data terminal 102 is an information device such as a personal computer, and the 0 office line 103 is connected to a subscriber telephone network, which is an external network.

The main device 101 has three information lines 104, 105, and 106.
and control line 107 are connected.

Next, the configuration of main device 101 will be described below. Crosspoint 109 is information &! 104.105.106 and central line 1
This is an analog switch for connection/disconnection with 03. IFUIIO sends and receives command frames on control line 107. Crosspoint 111 is an analog switch similar to crosspoint 109, and connects IFU 112 and information line 104.1 that sends and receives data frames.
05. Make connection/disconnection with 106. CPUI 13
controls the entire main device 101, and controls the cross point 10.
9.111 connect/disconnect instructions, IFUllo, 112
Controls each device by transmitting frames with and determining the contents of the frames.

A modulator/demodulator (modem) 114 connects the data frame with the data terminal 102 to an external network via the central office line 103.

Switch 115 connects modem 114 to station &1103. The difference between the main device 101 and the conventional one is that a cross point 111 connects information lines 104, 105, 106 and IF.
It is possible to connect with U112.

Next, the configuration of the data terminal 102 will be explained.

Analog switch 116 connects information line 104.105.1
06 and the IFU 118 via a changeover switch 117. The changeover switch 117 is for switching the IFU 118 between the control line 107 and the analog switch 116. The IFU 118 sends and receives command frames to and from the control line 107 and data frames to and from the information lines 104, 105, and 106. CPU119 is IFU
The CPU 1 performs control by transmitting/receiving frames via the 118 and determining the contents of the frames, and controls external devices such as the display 120 and the floppy disk 121.
19 is a main CPU of a personal computer or the like. The outlet 108 connects the bus and equipment inside the house.

The data transmission operation of this embodiment will be explained below.

The main device 101 and the data terminal 102 are connected via a control line 107 to the main device! 101 IFUIIO and data terminal 10
In this case, the start procedure for data transmission with the IFU 118 of No. 2 is performed using a command frame.
The changeover switch 117 of the data terminal 102 is set to 1. control line 1
07 side, and the CPU 113 of the main device 101
The CPU 19 of the data terminal 102 determines the information line to be used for data transmission and exchanges connection information with the other end of the external telephone network via the central office line 103 using command frames via the control line 107. When the connection with the other party's data terminal via the external telephone network is terminated, the main device 10
Using the control line 107 from IFUllo, the CPU 113 of the data terminal 102 instructs the CPU 19 of the data terminal 102 by a command frame to specify the number of the information line to be used for sending and receiving data frames and to start data transmission via the information line. . The CPU 113 of the main device 101 connects the specified information line and the IFU 112 using the cross point 111, and at the same time turns on the switch 115 to connect the modem 114 to the office line 103. Also, data terminal 1
When instructed to start data transmission over the information line, the CPU 119 of 02 switches the selector switch 117 to the analog switch 1.
16 side, and specify that the analog switch 116 be connected to the specified information line.

When there is data to be transmitted, the CPU 119 of the data terminal 102 instructs the IFU 118 to transmit this data frame. The IFU 118 connects information lines 104, 105 .
106, and on the main device 101 side, the data terminal 1 is connected from the cross point 111 via the IFU 112.
Data frames from 02 can be received. The CPU 13 of the manufactured W 101 transmits the transmission frame from the IFtJ 112 via the modem 114 and switch 115 to the office line 103 to the other party's data terminal connected to the external network.

Similarly, data from a partner data terminal connected via an external network is received by the CPU 13 via the station ff 1103, the switch 115, and the modem 114.
U112, cross point 111, information line 104.10
IFU 118 of data terminal 102 via 5.106
The CPU 119 receives the information.

In order to transmit data using the information line in this way,
The control line 107 communicates only command frames. Therefore, the command frame does not have to wait for the data frame as described in the conventional example. Furthermore, since the information lines are used exclusively for communication of data frames over the information lines 104, 105, and 106, it is possible to prevent a decrease in transmission efficiency of ≠-ta frames due to command frames.

In this embodiment, the processing load on the IFU does not increase and the processing load on the IFU does not increase.
can be used without modification. Note that various modifications are possible within the technical concept of the present invention. In this embodiment, communication between the data terminal 102 and a partner data terminal via an external network via the main device 101 has been described. ,
It is clear that the information line can also be used for communication with data terminals in the same household system and communication with printers and the like that are external devices of the data terminals. .

In addition, in the embodiment, the control line 107 is
and information line 104.105.106 changeover switch 117
are included in the data terminal 102, but the same operation can be performed even if the analog switch 116 is used as four cross points.

Furthermore, although the number of information lines is three in this embodiment, the number is not limited to this.

[Effects of the Invention] As explained above, according to the present invention, data transmission can be performed using an information line, so the control line is used exclusively for controlling equipment by sending and receiving command frames, and commands using data frames as in the past can be used. Frame queuing can be eliminated. Furthermore, since the data frame is transmitted by exclusively using the information line, it is possible to prevent the efficiency of data transmission from decreasing due to prioritization of the conventional command frame.

[Brief explanation of the drawing]

Figure 1 is a configuration block diagram of a data transmission system according to an embodiment of the present invention, Figure 2 is a typical configuration diagram of a data transmission system, Figure 3 is a configuration block diagram of an IFU, and Figure 4 is a conventional data transmission system. System configuration block diagram, Figure 5 (a)
, (b) is a frame format diagram. 101......Main device 102...Data terminal 104.105.106...Information line

Claims (3)

[Claims] (1) In a data transmission system in which a main device capable of transmitting and receiving frames and a plurality of data terminals are connected via a control line and an information line, and signals are transmitted and received between the main device and the data terminals, A data transmission system characterized in that a command frame in the signal is sent to the control line, and a data frame in the signal is sent to the information line. (2) The main device and the data terminal have switching means for switching between transmitting and receiving command frames over a control line and transmitting and receiving data frames over an information line. data transmission system. (3) The main device includes a first interface unit for exchanging data frames with the information line, a second interface unit for exchanging command frames with the control line, and a command A data terminal is equipped with a switching means for switching between transmitting and receiving frames over a control line and transmitting and receiving data frames over an information line, and a control means for controlling this switching means according to the type of frame. an interface unit for exchanging frames with the line; a switching unit for switching between sending and receiving command frames over the control line and sending and receiving data frames over the information line; 3. The data transmission system according to claim 2, further comprising a control means for controlling based on a command frame.