Reducing Medical Device Test Installation Qualification Using less Cables

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"We saved 24 days on the duplicate project build using our new methods."

- Jim Hall, MAC Panel

The Challenge:
Reducing total cost of ownership by trimming cabling cost for a PXI-based printed circuit board functional tester.

The Solution:
Combining the benefits of NI PXI modular instruments and third-party PXI interconnect from MAC Panel to reduce the number of days required to build a duplicate PXI test system from 35 person-days to 11 person-days, which saves time and increases profitability.

Author(s):
Jim Hall - MAC Panel
Greg Crouch - Medical Device Test Consultant

PXI has become a dominant industry standard for measurement and automation applications.  As a designer and manufacturer of system interconnect solutions, MAC Panel works with many NI customers in the automotive and medical industries to build PXI-based automated test solutions. During the early evolution of PXI, building a device under test (DUT) system interface was often a simple matter of selecting an interconnect receiver and NI PXI instruments, and then cabling them together. Today, our customers use NI PXI products for their unparalleled performance and density. One specific medical customer selected NI PXI hardware for its smaller footprint, but the cabling methods did not meet the requirements of the high-performance automated test system. As an NI Alliance Partner, MAC Panel sought to develop a PXI interconnection that eliminated cables between the NI PXI system and DUT, but still provided a way for the user to customize the system.

Project Challenge

A customer of MAC Panel that builds medical grade test systems in-house, defined a test bed for its wireless device test that needed to operate within the industrial, scientific, and medical (ISM) radio band to ensure the RF signal integrity met FDA reported requirements. The focus of the tester needed to be on all protocols within the 2.4 GHz ISM band, including Bluetooth, ZigBee, and IEEE Standard 802.11. The tester should also focus on functional level tests of the power supply, user interface, and human engineering features, that is, button response.

They complemented NI RF and modular instrument hardware with the NI WLAN Measurement Suite, NI ZigBee Toolkit, and NI Bluetooth Measurement Suite. Next they needed to define an interchangeable product interface that offered a common tester, lower costs, and reduced cabling. Cabling was a specific concern because of the engineering costs associated with duplicating the test platform, human errors made by connecting the numerous cables, and the time required to validate a system that was not repeatable in fabrication.

The Critical Role of NI Working With Third-Party Suppliers of PXI Accessories

The medical device customer selected the MAC Panel SCOUT as a substitute for direct cables between the PXI instruments and the receiver connector, along with a complement of NI modular instruments and switches. A connection assembly, called a Direct Access Kit (DAK) attaches to the NI PXI instrument face connector to form a single assembly and to each NI PXI instrument, which includes metal shielding to eliminate noise. The SCOUT family of DAK adapters provided an off-the-shelf solution to connectivity with all NI modular instruments. However, we also needed a customer-defined adapter.

Figure 1. Test System Setup

Figure 2. Traditional Cabling Versus DAK Adapters

The customer used NI Ultiboard software and NI Multisim software to lay out a custom DAK module design. The DAK adapter incorporated custom circuitry for LVDS, isolation to medical grade, and signal deamplification. The SCOUT receiver offered nontraditional instrument connectivity and signal path routing.

Figure 3. Time Savings in Building Repeat Systems

Benefits of Using an NI-Based Solution and the Bottom-line

In the past, building automated test interconnect using standard or custom cables offered interchangeability.  Today’s high-fidelity signals and complex coupling required a solutions-based approach from vendors partnering together. The end customer used MAC Panel SCOUT technology, along with NI hardware modular instruments and Multisim software to create a custom, yet modular, system that addresses signal integrity from the NI PXI instrument down receptacle the direct DUT interface.

Author Information:
Jim Hall
MAC Panel

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