| 摘要 |
PURPOSE:To attain the bypass control from outside through the maintenance, periodical check, etc. and to facilitate to conduct easy bypass control, by carrying out the loop-back control through a monitor station of a double-loop data way system without giving any effect to the existence of a bypass station. CONSTITUTION:A loop connection is secured among data transmission stations 201-20n by circuits 11 and 12 of a double-loop transmission line 10. The station 201 is used as a monitor station, and stations 202-20n are used as ordinary stations. These stations 201-20n have the same constitution. A switch circuit 31 connected to the line 10 is provided to each of those stations, and a connection deciding circuit 33 and a bus control circuit 34 are connected to the circuit 31. Furthermore a control part 32 connected to a nonvolatile memory 43 is connected to the circuit 33. Then the loop-back control of the station 201 is carried out without giving any effect to a bypass station. Thus the bypass control is possible from the outside by the maintenance, periodical check, etc. |
