| 摘要 |
PURPOSE: To obtain an improved remote resistance measuring system especially fitted for judging whether trouble is present in the system. CONSTITUTION: The connection lead wire 25 to a three- or four-wire type resistance temp. element (RTD) 24 is multiplied at the input of an apparatus by a four-channel analogue multiplexer 28 and the output of the multiplexer 28 is connected to a voltage-frequency converter 32 and this frequency output is used as the input to a microprocessor. The microcontroller 22 issues an address to the multiplexer 28 and the connection wires to a remote RTD sensor 24 are individually separated in an insulated state to check disconnection. In a test mode, the output of the multiplexer 28 connects known impedance to the output of the multiplexer 28 and it is judged which of RTD connection wires 25 has a flaw. |
