Interface conversion cable used for detecting serial port circuit as well as application method thereof

The invention relates to an interface conversion cable used for detecting a serial port circuit. The interface conversion cable is composed of a conversion cable A and a conversion cable B, the conversion cable A is composed of three parts, namely an RS-232 DB9 port, a network port and a network cable; the conversion cable B is composes of three parts, namely an RS-232 DB9 port, a network port anda network cable; terminals 2-8 of each RS-232 DB9 port are sequentially welded with core wires 1-7 at one end of the corresponding network cable according to a connection method required by calculation, a bonding clamp at a joint of each RS-232 DB9 port fixes the corresponding network cable and is encapsulated by virtue of a plastic housing of the joint of the RS-232 DB9 port, and core wires 1-7at the other end of the corresponding network cable are woven tidily, are inserted into slots 1-7 of the corresponding network port according to the sequence and are connected in a crimping way. The interface conversion cable