JPS62150951A - Information transfer circuit - Google Patents

Abstract

PURPOSE:To avoid the collision of information on a transmission line without increase in the overhead of the software by inserting a changeover switch to a transmission line, storing a data sent from other station into a memory at the sending of a signal and sending the data again to the transmission line after its own station information is sent. CONSTITUTION:A transmission circuit 3, and the 1st and 2nd reception circuits 2, 5 are provided to transmit/receive information via a unidirectional transmission line and a changeover switch 4 and an FIFO system register 6 are provided. The changeover switch 4 cuts off a low-order side of the transmission line at the transmission of information to input an input signal to the 2nd reception circuit 5. The register 6 of the FIFO system stores an output of the 2nd reception circuit 5 and the stored content is sent to the low-order side of the transmission line via the transmission circuit 3 after the end of transmission of information.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an information transfer circuit that transmits and receives information to and from a unidirectional transmission path using a random access method.

(Prior Art) Conventionally, this type of information transfer circuit has a token system in which a token indicating that the right to send and receive is held between the information transfer circuits to avoid information collisions, and a token system in which the transmission path is monitored. C8MA that generates information when no signal is on the transmission path.
The C8MA/CD method, which detects signal collisions caused by multiple transmissions in the csMA method, is well known.

(Problems to be Solved by the Invention) Among the above-mentioned conventional information transfer circuits, the token method requires complicated procedures for sending and receiving tokens and regenerating tokens when they are lost, resulting in large communication overhead and The disadvantage is that it requires complex software.

The C8MA method requires a means to detect and retransmit collided information, which has the disadvantage of increasing communication overhead, while the C8MA/CD method requires a circuit to detect signal collisions. At the same time, it has the disadvantage that it requires additional air for retransmission of information.

An object of the present invention is to provide an information transfer circuit that includes a transmitting circuit and a receiving circuit and transmits and receives information via a unidirectional transmission path, in which the transmission path is cut when transmitting information and the signal is input to another receiving circuit. Furthermore, by holding the output of the receiving circuit in a FIFO type register and sending the held content to the transmission path via the transmitting circuit after the information has been sent, the above disadvantages are eliminated and complicated software is not required. An object of the present invention is to provide an information transfer circuit configured to prevent the above information from being transferred.

(Means for Solving the Problems) An information transfer circuit according to the present invention includes a transmitting circuit and first and second receiving circuits, and is configured to transmit and receive information via a unidirectional transmission path. There is a changeover switch,
It is configured to include a FIFO type register.

The changeover switch is used to cut off the lower side of the transmission path and input the input signal to the second receiving circuit when transmitting information.

The FIFO type register is used to hold the output of the second receiving circuit, and after the transmission of information is completed, to send the held contents to the lower side of the transmission path via the transmitting circuit.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an information transfer circuit according to the present invention. In Fig. 1, l is a unidirectional transmission line, 2Fi is a receiving circuit, 3 is a transmitting circuit, 4 is a changeover switch, 5 is a second receiving circuit, 6 is a FIFO type register, and 7 is an information transfer port □ path. It is.

In FIG. 1, a transmission path 1i is a unidirectional transmission path from right to left, and a receiving circuit 2 and a transmitting circuit 3 are connected to this to transmit and receive information.

Furthermore, a changeover switch l is placed in the middle of the transmission line l,
The signal switched here is received by the second receiving circuit 5. The data in the second receiving circuit 5 is processed using a first-in, first-out method (F
IFO) is held in register 6. The register 6 is connected to the transmitting circuit 1, and the held data is sent to the transmission line. When the information transfer circuit 7 does not send out a signal, the changeover switch 4 is closed to the transmission line side, and the information is received by the receiving circuit 2 and can also freely pass through this station.

On the other hand, when the information transfer circuit 7 sends a signal, the signal is sent from the transmission circuit 3 to the transmission path when there is no signal on the transmission path. Signals received from other stations during transmission with the terminal closed to the side are held in the register 6. After the transmission circuit 3 completes data transmission, the data held in the register 6 is transmitted to the transmission path.

(Effects of the Invention) As explained above, the present invention inserts a changeover switch into the transmission path, stores data sent from another station when a signal is transmitted in memory, and then reuses the data after transmitting own station information. By sending the information to the transmission path, there is an effect that collisions of information on the transmission path can be avoided with no increase in software overhead and only a slight increase in circuitry. Moreover, according to the present invention, since there is no information collision, the software-based collision detection and retransmission procedures can be greatly simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an information transfer circuit according to the present invention. l... Transmission line 2.5... Receiving circuit 3... Transmitting circuit 4... Selector switch 611, register 7... Information transfer circuit

Claims (1)

[Claims] An information transfer circuit for transmitting and receiving information via a unidirectional transmission path, comprising a transmitting circuit and first and second receiving circuits, wherein the lower side of the transmission path is disconnected when transmitting the information. a changeover switch for inputting an input signal to the second receiving circuit, and an output of the second receiving circuit, and after the transmission of the information is completed, the held contents are transmitted through the transmitting circuit. An information transfer circuit comprising: a FIFO type register for transmitting data to a lower side of the transmission path.