Thus result in The U2A and U4A are the OD output inverter, U1A and U3A are the input inverter in figure 1.Each tested point of the apparatus is composed of input end and output end. The output end provides the stimulus vector, and is connected with the OD output inverter, U2A and U4A. The input end collects measurement vector, and is connected with the input inverter, U1A and U3A. We check if the output positive value point to point by the interior circuits of ARM and CPLD matches the input positive value to determine the good or bad wire connection.