Using FPGA as synthetic instrumentation in automated test sets: Benefits and examples

The use of Field Programmable Gate Array (FPGA) hardware in Test Program Set (TPS) development is highly beneficial due to its ability to be reconfigured on the fly to simulate various ATE instruments or unique signals generated from discrete hardware components. FPGA hardware can by utilized for creating an array of synthetic instruments; and by utilizing a FPGA, a single piece of hardware can be used for multiple TPS applications, saving both time and money. Not only can FPGA hardware be used as a digital filter (which can replace physical discrete RC-circuits and other filtering circuits) but it can also aid in the simulation of obsolete parts or instruments commonly found when re-hosting TPSs from legacy test sets. Hardware obsolescence is a common problem in maintaining ATS systems for the life cycle of its intended use. When re-hosting or developing new ATS equipment, it is important for designers to plan for the longevity of their hardware. FPGAs solve this problem by simulating output signals from these obsolete instruments/parts and by doing so, end users can more easily maintain their TPS equipment when it has been put out into the field. This paper highlights a few successfully developed FPGA implementations used as synthetic instrumentation in an ATS environment. These implementations were designed for various CACI Common Bench-Top Automatic Test Set (CBATS) 201 TPS systems. The CACI CBATS 201 is a bench top tester built around a National Instrument's PXI chassis and utilizes a PXI-7852R Multifunction RIO with Virtex-5 LX50 FPGA. The FPGA applications pertaining to ATS environments described thought-out this document include: simulating an aircraft Lift Vane Transducer (LVT) output signals, simulating synchro leg voltages, and simulating custom digital communication protocol chip hardware. The applications mentioned here are currently integrated in delivered TPS, and are being used to aid in the depot testing of various military aircraft Line Replacement Units (LRU).