JPH01251932A - Serial data communication circuit - Google Patents

Abstract

PURPOSE:To realize serial data communication which does not require any complicated communication line switching process and is high in reliability against the disconnection, etc., of the communication line by allowing a first- come deciding circuit to select data received from a main communication line and those from a standby communication line. CONSTITUTION:The computer 1 of a transmission station sends serial data through a transmission circuit 2 and the circuit 2 has two sets of transmission drivers 3 and sends the same data to a main communication line 8 and standby communication line 9. A reception circuit 7 has two sets of receivers 6 and receivers data from the lines 8 and 9. The received data are decided about their arriving order at a first-come deciding circuit 5 and only the first arriving received data are inputted to the computer 4 of the receiving station. Therefore, a serial data communication circuit which does not require any complicated line switching process and is high in reliability against the disconnection, etc., of the line can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a serial communication system which has a two-way communication path, a main line communication path and a backup line communication path, and has backup means against disconnection of the communication path. It relates to data communication circuits.

[Conventional Technique tFiE Conventionally, a serial data communication circuit that has a main line communication path and a backup line communication line sends data only to the main line communication line during normal operation, and when a problem such as a break in one line communication line occurs, There are two types: one that only switches to the backup line communication channel and communicates, and the other that receives data on both the main line communication channel and the reserve 4IR line communication channel during normal times, and uses only one of the data in the computer etc. that performs the reception processing. there were.

[Problems to be solved] Among the conventional serial data communication circuits mentioned above, those that switch to the backup line communication path only in the case of a disconnection, etc., perform reception processing when switching from the single line side to the backup line side. Since switching processing is required using a computer or the like, there is a problem in that switching takes time.

Further, in a system that performs reception processing on both the main line side and the standby line side, there is a problem in that the load on the computer that performs the reception processing increases.

The present invention has been made in view of the above-mentioned problems.
without placing a large load on the receiving station's computer.
Moreover, it is an object of the present invention to provide a serial data communication circuit that does not require complicated communication path switching processing and is highly reliable against communication path disconnections.

[Means for Solving Problems] In order to achieve the above object, the present invention provides a serial data communication circuit having a main communication path and a backup communication path,
A transmitting station that transmits the same data in two directions, the main line communication path and the reserve line communication path, and a first-come-first-served determination circuit that determines where received data arrives from the two directions, the main line communication line and the reserve line communication line. and a receiving station that receives only the data that arrived earlier in time among the received data from the two directions.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In this embodiment, the computer 1 of the transmitting station transmits serial data through the transmitting circuit 2.

The transmitting circuit 2 includes two sets of transmitting drivers 3, and transmits the same data to a single line communication path 8 and a backup line communication path 9, respectively.

The receiving circuit 7 includes two sets of receivers 6, which receive data from a main line communication path 8 and a backup line communication path 9, respectively. The first-arrival determination circuit 5 determines the arrival of the received data, and only the received data that arrived one hour earlier is input to the computer 4 of the receiving station.

In this embodiment, since the two received data on the main line side and the backup line side are selected according to the first-come-first-served rule, even if data from one communication channel is not received due to a disconnection of one communication channel, the data from the other communication channel is reliably selected. can receive data from.

[Effects of the Invention] As explained above, the present invention uses a first-come-first-served judgment circuit to select received data from a single-line communication path and received data from a backup line path, without placing a large load on the receiving station's computer. .

Furthermore, there is an advantage that there is no need for complicated communication path switching processing, and serial data communication can be performed with high reliability against disconnection of the communication path.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. l: Transmitting station computer 2: Transmission circuit 3: Transmission driver 4: Receiving station computer 5: First-come-first-served judgment circuit 6: Receiving cash register 8 7: Receiving circuit 8: Main line communication path 9; Reserve @ line communication path Agent: Patent Attorney Kihei Watanabe

Claims (1)

[Claims] In a serial data communication circuit having a main line communication path and a backup line communication path, a transmitting station that transmits the same data in two directions, the main line communication path and the backup line communication path, and a transmitting station that transmits the same data in two directions, the main line communication path and the backup line communication path, It is characterized by comprising a first-arrival determination circuit that determines the arrival of received data from the two directions, and a receiving station that receives only the data that arrived earlier in time from among the received data from the two directions. Serial data communication circuit.