What is a bus wire test?
The Agilent Medalist i3070 in-circuit tester automatically generates boundary scan bus wire tests.
The bus wire test looks only for opens on all the bussed boundary scan devices that are not tested by the interconnect test. The boundary scan driver pins are tested one at a time to ensure that all possible opens which could occur are tested.
Figure 1 shows examples where boundary scan opens could be missed during interconnect testing:
1. If only one driver per bussed wire is enabled during the interconnect test, opens on the disabled drivers would not be detected.
2. If two or more drivers must be enabled to satisfy the interconnect test and they drive the same node, an open on one of these drivers would not be detected.
3. If two or more drivers must be enabled because they are connected to the same control cell, an open on one of these drivers would not be detected, even in the bus wire test,
Figure 1: Examples of scenarios where opens could go undetected by interconnect test on bussed wires.