Intelligent DAQ Speeds Defibrillator Testing

Medtronic was challenged to create a new automated high-voltage (HV) defibrillator tester with the flexibility to test four product types while reducing overall test time.

The defibrillator test executive PC communicates with the system via an NI LabVIEW graphical user interface.

The previous system ran 12 test modules using parallel port communication and only tested one type of HV defibrillator. Medtronic achieved a maximum communication rate of 20 kHz using the parallel port, and because it tested each of the 12 devices sequentially, the total test sequence took two hours and 15 minutes.

The Test Engineering Group at Medtronic used NI R Series intelligent data acquisition (DAQ) hardware and the NI LabVIEW FPGA Module to create an asynchronous environment in which all 12 devices under test (DUTs) could run autonomously with an independent communications port. With two National Instruments PXI-7811R intelligent DAQ modules, Medtronic implemented SPI and JTAG digital communication protocols and increased communication rates from 20 kHz to 1.7 MHz. By using the parallelism of the LabVIEW FPGA Module, each of the 12 DUTs functioned independently, reducing the overall test time to only 48 minutes.

The ability to test any of four different product types dramatically improved the efficiency of the automated test system. Each NI PXI-7811R contains 160 digital I/O (DIO) lines and is responsible for testing six devices. Medtronic only needed three of the four digital connectors on each intelligent DAQ PXI module, with each connector (40 DIO lines) communicating with two different DUTs. The same LabVIEW FPGA code runs on both PXI modules, and a National Instruments PXI-8187 host controller launches each test program when instructed by a test executive PC via TCP/IP. The test executive PC is the master controller for the automated HV defibrillator test system, providing the user interface for production operators to select which products to test. Medtronic graphically programmed the software for every component of this automated test system in LabVIEW.

Using the flexibility and parallelism of the LabVIEW FPGA Module, Medtronic increased the types of HV defibrillators it could test and reduced the overall test time for 12 devices by 66 percent. With approximately 600 FPGA interactions per test program per module, the NI intelligent DAQ hardware handles all communication traffic and maintains independent DUT operations at very high rates. Medtronic now tests defibrillators faster and more efficiently, while still ensuring the reliability required for all medical devices that are designed to save lives.

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This article first appeared in the Q4 2006 issue of Instrumentation Newsletter.

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