Abstract: The wiring of system contacts (18) to board probes (20) on a fixture (16) that is used to connect nodes of a board under test to system pins (14) of a multiplexed circuit tester (10) is performed independently of test generation for the type of circuit board with which the fixture (16) is associated. Conflict lists that the pin-assignment program uses to determine which system contacts to wire to which board probes are generated without using the output of the program for generating the board test. For driver/sensor probes, a conflict list for the in-circuit test of a given device includes all input and output nodes of that device as well as all input nodes of devices whose output terminals are connected to nodes of the device under test. The resulting wiring results in few conflicts without requiring many more tester resources than conventional pin-assignment approaches do, and it can be employed without adding to manufacturing lead time.

Abstract: A circuit tester (12) tests an electronic circuit (10) to determine which of a number of bus devices (16, 18, and 20) on the circuit (10) is stuck in an asserting state and is thus keeping a bus (14) at the asserted voltage level. A back-driving source (21) back-drives the bus (14) to its de-asserted level, and each of the devices (16, 18, and 20) is enabled individually in succession. When a device is enabled, a current meter (22) determines whether the bus current increases as a result. If so, the given device is not the defective device that is keeping the bus asserted. If there is no current change, the device is the defective one. A current limit is imposed on the back-driving source (16). This limit depends on the particular device being enabled; the limit is set higher than the quiescent assertion current on the bus but less than the sum of the quiescent current and the assertion-current capacity of the device being enabled.