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.