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Sanmina-SCI Exceeds Throughput Goals with PXI Tester and Multithreaded Software

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High-Speed PXI-Based Test System for Calibrating Medical Devices

Author(s):
Mike Oehrlein - Sanmina-SCI Corporation

Industry:
Medical/ Medical Instrumentation, Electronics

Products:
Digital Multimeters, LabWindows/CVI, PXI/CompactPCI, TestStand,

The Challenge:
Developing a compact and high-speed functional test station that performs parallel calibration on eight medical devices.

The Solution:
Using National Instruments LabWindows/CVI, NI TestStand, and high-performance PXI modular instruments to develop an automated and modular production tester with database and statistical process control capability for medical device calibration.

"Our customer was satisfied with the completed test system and has plans to expand the system by building additional stations to satisfy product demand and adapting fixtures and software for the next-generation devices."

Test System Requirements

Sanmina-SCI, one of the world’s leading contract manufacturers, recently developed a test application for a medical device that measures blood glucose levels by measuring the current and impedance characteristics produced from an electrochemical reaction. We needed to build a functional test and calibration system that complied with FDA regulations, calibrated the DC amplifier circuits of the measurement engine, and verified the operation of other critical support circuits contained within the device under test. Additionally, in real time, the system had to switch a variety of input loads into the measurement engine to emulate the complex task of simulating blood response. Lastly, the system had to reliably and repeatedly process up to 83,000 devices per week while maintaining a cycle time of effectively 30 seconds per device.

Because of these requirements, we chose a flexible software framework that facilitated multithreaded parallel testing; efficient communication with commercial databases; and a custom software interface with strict user management for administrators, supervisors, engineers, and manufacturing operators.

Compact, High-Speed Test Solution

The Sanmina-SCI design team knew from previous experience that a design solution based on traditional instrumentation alone could not meet test-throughput needs. For this application, the design team needed to build a hybrid test system based on PXI and GPIB modular instruments as well as a custom FPGA-controlled interface to the device under test that could test eight devices in parallel. The completed test system included eight NI PXI-4070 6½-digit FlexDMM devices, eight NI PXI-6533 high-speed digital I/O modules, an NI PXI-6508 general-purpose digital I/O module, a GPIB-based power supply, and an LCR meter. The FlexDMM delivered the throughput and accuracy the design team needed to acquire all of the voltage and current measurements on the device under test. The design team used the PXI digital devices to communicate with the DUT and write the calibration values to the onboard EEPROM.

We chose NI TestStand for test management software because it provided test sequencing of LabWindows/CVI and C# .NET modules, native parallel testing support, and a comprehensive user management framework. Its flexible and open source code operator interface also gave our design team full control over the look and feel of the operator interface. Rather than worry about thread management and synchronization, we could use NI TestStand to focus on the details of the test management process. We used LabWindows/CVI for test module development because of the built-in test and measurement functions and user interface controls, in addition to the SQL database connectivity capabilities. With LabWindows/CVI, we could create highly efficient ANSI C source code that integrated with modular instruments and GPIB. By using commercially available software such as LabWindows/CVI and NI TestStand, we kept software development time and costs to a minimum.

Exceeded Yield Expectations

The PXI-based tester provided a compact calibration system that met the high-speed throughput requirements while exceeding the initial system yield requirements by achieving yields greater than 95 percent in production.

The customer was satisfied with the completed test system and has plans to expand the system by building additional stations to satisfy product demand and adapting fixtures and software for the next-generation devices.

 

For more information, contact:

Mike Oehrlein

Sanmina-SCI Corporation

13000 S. Memorial Pkwy

PO Box 1000

Huntsville, AL 35807

Tel: (256) 882-4800, ext. 8587

Fax: (256) 882-4871

E-mail: mike.oehrlein@sanmina-sci.com

www.sanmina-sci.com

 

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