JPS58177053A - Data communication system - Google Patents

Abstract

PURPOSE:To improve the communication efficiency, by allowing the communication to an other communication device while a communication device transmits the next response. CONSTITUTION:A control circuit 5 sets the right of communication and informs it to a processing circuit 3 and a transmission circuit 4 when a command addressed to the circuit 5 is detected from a data signal received from a bus BUS via an MODEM circuit 1 and a reception circuit 2, and it is informed to a processing circuit 3 and a transmission circuit 4. The circuit 4 transmits a response to the BUS via the circuit 1. When the transmission of command is possible for the 1st communication device corresponding to the received command, the circuit 3 transmits the command to the BUS via the circuits 4 and 1 immediately. If this is impossible and there exists a command to be transmitted to the 2nd communication device, the command is transmitted to it. When the circuit 3 transmits the command, the circuit 5 turns over the right of communication to the 3rd communication device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data communication device in which a plurality of communication devices share a communication line and perform data communication between two communication devices in a time-sharing manner.

Conventionally, there have been devices of this type that have a connection configuration as shown in FIG. The communication devices CMI to CM3 are commonly connected via a bus, and for example, when the communication device CMI communicates with the communication device CM2, they communicate by occupying the bus between them. According to this communication method, even if there is a long interval between sending the next data, that is, a period when the bus is not actually used, it cannot be used effectively, resulting in a decrease in communication efficiency. .

The present invention was made in order to eliminate the drawbacks of the conventional ones as described above, and is used in a data communication system in which a plurality of communication devices share a communication line to communicate data. When a command for data communication is sent to the second communication device, the second communication device
A data communication system that can improve communication efficiency by transmitting a response to a third communication device, acquiring communication rights to enable communication, and establishing communication with a third communication device. The purpose is to provide.

An embodiment of the present invention will be explained below with reference to the drawings. FIG. 2 is a block diagram of a communication device according to the present invention. The modem circuit 1 transfers the data signal received from the bus BUD forming the communication line to the processing circuit 3 via the receiving circuit 2.
- It has the function of receiving and receiving data signals from the processing path 3 via the transmitting circuit 4 and sending them to the bus BUS. When the control circuit 5 detects a command addressed to itself from the data signal, that is, the command received via the receiving circuit 2, the control circuit 5 transmits the signal to the transmitting circuit 4.
It has the function of transmitting a response from and acquiring communication rights.

Next, the data transmission procedure according to the present invention will be explained with reference to the timing diagram shown in FIG. For example, the communication device CMI sends a command C1 consisting of a data sending request to the communication device CM2 at time t1. In response, the communication device CM2 transmits the response R1 at time t2 and acquires communication rights in the system. In this case, communication device i1cM2 cannot immediately send a command to communication device CMI in response to the data sending request by command C2, but since it has a command to send to communication device CM3, A command C2 is sent to the communication device CM3. Upon receiving the command C2, the communication device CM3 sends a response R2 and acquires communication rights, and sends the command C3 to the communication device CM2 at time t4. On the other hand, the communication device CM2 receives the communication device C at time t.
It sends a response R5 to M3 and acquires communication rights again. At time t6, the communication device CM2 becomes able to send the command C9 to the communication device CMI and sends it. Below, communication device CMI.

Commands and responses are exchanged between 0M2 and time t8.
completes the communication.

Immediately, from the sending of the response R□ to the sending of the command C9, there is no communication between the communication devices CMI and 0M2, and the communication device C takes advantage of the fact that the bus BUS is empty.
Communicate between M2 and CM3.

In FIG. 2, when the control circuit 5 detects a command addressed to itself from the data signal received from the bus BUS via the modem circuit 1 and the receiving circuit 2, it sets the communication right and transfers it to the processing circuit 3 and the transmitting circuit. I know on 4th. In response, the transmitting circuit 4 sends a response to the bus BUS via the modem circuit 1, and the processing circuit 3 immediately sends the command to the first communication device corresponding to the received command if it is possible to send the command. It is sent to the bus BUS via the circuit 4 and the modem circuit 1, and if this is not possible and there is a command to be sent to the second communication device, a command is sent to this. When the processing circuit 3 sends the command, the control circuit 5 transfers communication rights to the third communication device.

Note that although the above embodiment describes the case of three communication devices, there may be three or more communication devices.

As described above, according to the present invention, it is possible to prevent a specific communication device from occupying a communication line for a long period of time without actually communicating, and to prevent a specific communication device from occupying a communication line for a long period of time without actually communicating. Since communication is allowed, the actual usage time of the communication line increases and communication efficiency can be improved.

[Brief explanation of the drawing]

ii Figure 1 is a diagram showing an outline of interconnection of communication devices, Figure 2 is a block diagram showing the configuration of a communication device according to an embodiment of the present invention, and Figure 3 is a timing diagram of communication between 4G devices according to the present invention. It is. CMI to CM3...communication device, 1...modem circuit,
2: Receiving circuit, 3: Processing circuit, 4: Transmitting circuit, 5: Control circuit. Agent Makoto Kuzuno (and 1 other person) Figure 2 Figure 3

Claims (1)

[Claims] A plurality of communication devices sharing a communication line are provided, and when the first communication device sends a command to the second communication device, the command is sent to either the second communication device or the first communication device. In a data communication system that communicates data by sending a response, communication that occupies the communication line during the period from when a command from the communication device is detected through the communication line until the command is sent from the communication device. The control circuit that sets the communication right, and the communication device that sent the command addressed to the nuclear communication device or other communication device when the control circuit sets the communication right, and the processing circuit that does not send the command to each of the above. A data communication system characterized by being equipped with a communication device.