Optimizing functional-test throughout in PXI-based automated test systems

by Alan J. Lesko, Agilent Technologies , TechOnline India - October 19, 2010

To help understand key concepts in DAT, let’s consider the manufacturing test plan for a high-volume automotive engine control unit (ECU). A review of the test plan shows that it is very transaction intensive, with many DUT setups and measurement transactions over the course of the test.

To ensure ongoing competitiveness, most manufacturing engineers are looking for new and better ways to optimize test throughput while ensuring measurement integrity. Manufacturing targets can be very aggressive and two key factors — testing methodology and instrument selection — can make or break a test-time budget.

The selected test methods must be efficient, focusing on validating functionality of the device under test (DUT) while gathering parametric data to help improve the manufacturing process. Also, instrument selection must consider both speed and measurement integrity. PXI test platforms form a good basis for high throughput functional test systems. This article will discuss test methods and instrument characteristics that will help ensure successful implementation of future test systems.

Improving functional test

In manufacturing, test plans take various forms. A true functional test places the DUT into an electrical environment that emulates the actual application. Connections are loaded and driven as if the DUT was in the final application and the unit is closely observed to verify correct performance.

Unfortunately, a true functional test can be extremely slow and therefore may be impractical in many instances. An alternative test method called DUT-assisted test (DAT) utilizes a communication link to the DUT combined with built-in test commands to isolate and exercise specific portions of the device. This approach yields greater flexibility during the test plan and enables a very fast and efficient testing. Best-in-class manufacturers use DAT methods to achieve high test coverage and a throughput advantage.

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