LXI: A Shift in the Functional Test Paradigm

LAN-based instrumentation, leveraging the advantages that LXI (LAN extensions for instrumentation) has to offer, has resulted in a paradigm shift in functional test methodology. The early days of test program design involved utilizing test instrumentation with parallel interfaces such as IEEE-488. These interfaces were slow and had limited bandwidth, but the response to individual message queries was relatively quick and ideal for multiple command- response sessions used for setup, control, and data gathering purposes. The very nature of LAN-based instrumentation requires a re-evaluation of this approach and with it the classis test paradigm. The TCP/IP protocol stack, triggering, synchronization, security, and inter-device interaction are fundamental areas of LAN-based test that provide tremendous opportunity, but also involve understanding any subtle differences that may exist. Other parallel advances in instrumentation such as powerful inexpensive digital signal processors, FPGA devices, and large onboard memory also has changed the way particular test sequences are implemented. The need to rely on the host computer for processor intensive operations is no longer needed, and therefore reduces the burden on both the communications interface and the host. This paper will address how the adoption of LAN-based instrumentation changes the way test engineers approach test program set (TPS) design. It will also provide recommendations to leverage the strengths that LAN-based test has to offer.