|Open fault detection in boards with multiple BS chains can
be done sequentially or simultaneously in each chain, since each open
fault does not affect more than one interconnect. A different situation
takes place when considering short-circuit faults, since their detection
requires the two shorted interconnects to be active (and with opposite
logic values applied) at the same time. The binary partition algorithm
presented in the previous section guarantees this condition, but further
attention has to be given to the case of boards with multiple BS chains,
since it is not possible to ignore the case of two interconnects belonging
to different chains.
The binary partition algorithm will generate the test vectors for the whole group of interconnects in the board, regardless of how many BS chains exist or of what particular BS chain(s) each interconnect belongs to. However, the application of test vectors in each chain has to be done in a co-ordinated manner, through a protocol that may be described as follows for each vector:
This test protocol for boards with multiple BS chains guarantees correct application of the test vectors generated by the binary partition or by any other test vector generation algorithm.