| 摘要 |
PURPOSE:To increase the usage efficiency of a loop data transmission system, by performing the confirming test for repair at a data terminal section without giving interference to the operation of the loop data transmission system. CONSTITUTION:A data transmitter consists of a transmission/reception section 10 for a transmission line 1, a transmission/reception section 20 for a transmission line 2 and a data terminal 30. A switching control section 303 provided at the data terminal, in response to the state of a clock detecting signal at the both transmission lines, transmits one of a switching signal which connects the section 30 to the line 1 and by-passes the line 2, a switching signal which connects the section 30 to the line 2 and by-passes the line 1, and a switching signal which by-passes the lines 1 and 2 and disconnects the section 30 from the lines, to data terminal switching section 302, switching sections 104, 204, for switching operation. |
