Verfahren und Gerät zum Prüfen von Ein-/Ausgabeverbindungen des Randsteckverbinders einer Schaltkreiskarte mit Boundary Scan

摘要

Both the input/output connections (16) of a circuit board (10) and the boundary scan devices (121 - 12n) thereon can be tested simultaneously by boundary scan techniques using a Serial Test Extension Module (STEM) (28) which mates with the circuit board. The STEM (28) contains at least one boundary scan register (36) which makes an electrical connection with a separate circuit board input/output connection (16) when the STEM mates with the board. The boundary scan registers (36) within the STEM (28) are serially connected in a chain, that is, connected in series with a chain of serially connected boundary scan registers (20) within the boundary scan devices (121 - 12n). By launching a known bit stream into the chain of boundary scan registers (20) and (36) and thereafter shifting out the bits and comparing them to a reference bit stream, representing a defect-free condition, faults in the input/output connections (16) and/or in the devices (121 - 12n) can be detected.