bus thus the possibility of adding ambiguity to the faults is reduced or eliminated the present invention is performed real time and the bit data is mapped to identify the subsystem and a particular bus channel utilizing the controlling computer by adding accumulators to the bus operating system the fault detection and isolation method of the present invention is able to capture single events and report them real time given the ability to identify the difference between a fault and a failure associated with a device on the bus further the capability to map the fault to a trunk cable problem or an interface fault from the data bus coupler to the subsystem is provided generally the non intrusive bus fault detection and isolation system of the present invention achieves fault detection fault isolation through exercising and interpreting bit results bit performs the basic fault detection functions which are then expanded on by the present invention by including the physical configuration mapping of the i o to perform fault isolation on the bus fig1 shows a typical dual redundant bus topology in particular a dual redundant bus 10 comprises a main data bus a 102 a main data bus b 104 and groups of remote terminals 106 116 the main data bus a 102 comprises a bus terminator 118 a first data bus coupler 120 a connecting wire 122 a second data bus coupler 124 a connecting wire 126 a third data bus coupler 128 and a bus terminator 130 the main data bus b 104 comprises a bus terminator 132 a first data bus coupler 134 connecting wire 136 a second data bus coupler 138 a connecting wire 140 a third data bus coupler 142 and a bus terminator.