Pickering Partner Delivers Automated Fuse Tester for Automotive Applications 

When an automotive fuse manufacturer needed a production line test set-up, it turned to Automated Software Technology (AST), an engineering company that develops high-quality custom PC-based test, measurement, and control systems, and a Pickering Partner Program member. The customer required the test system to measure the resistance of each fuse and compare it to an entered value. The system had to determine if the fuse was acceptable or faulty and save the results for the test. The customer specified that the software had to be easy to use and interface with different hardware components.

AST focuses on data acquisition and instrument control applications. The Michigan-based company specializes in LabVIEW programming and is also a Pickering Partner, so they were also familiar with the switching aspects of the design. Signal switching is critical because it connects resources (DMM, power supply, etc.) to the DUT (Device Under Test)—see Figure 1. Using a high-quality switch, a single piece of hardware can be used to test multiple measurement points. This can help reduce costs as only one hardware resource is needed.

Diagram of signal switching in a test system

Figure 1: Diagram of signal switching in a test system

AST partnered with another Michigan company, MVB, a highly experienced engineering team that provides manufacturing automation solutions to many industries. MVB built the test fixture and programmed the PLC for machine operation. AST developed the custom LabVIEW software that provided the user interface and communicated with the measurement hardware. The software needed to interface with a PLC via digital inputs and outputs, a Pickering high-density PXI multiplexer, and a micro-ohm meter. Housed in Pickering’s 2-slot LXI/USB chassis, the PXI multiplexer was used to route the signal from each fuse to the meter, thereby reducing cost because only one meter was required for all the measurements.

Pickering offers the industry's most comprehensive range of PXI and LXI solutions. The PXI standard has enabled Pickering to design large-scale PXI switching products that would otherwise be difficult and expensive to implement as modular products. The multiplexer chosen by AST was Pickering’s 40-670C-021-24/4, a 24-channel, 4-pole MUX, and is part of a family of very high-density multiplexer modules that feature a wide range of switching configurations. Capable of switching up to 150VDC/100VAC, 0.5A (10W maximum power), and fast operating speeds of under 500µs, the module has up to 198 switch pins available with 1-, 2-, 4-, 8-, 16- or 32-pole switching formats. Automatic isolation switches reduce capacitive loading in large systems, and a screened option provides improved noise performance. High-reliability Pickering reed relays are used for high performance and long life. The MUX is supported by Pickering's eBIRST switching system test tools.

Figure 2: Pickering’s high-density multiplexer module

Figure 2: Pickering’s high-density multiplexer module

The Pickering 2-slot LXI/USB modular chassis offers a small, lightweight form factor, making it ideal for portable, benchtop, and space-restricted applications. The chassis is designed for desk or rack mounting and features remote control via USB or LXI Ethernet and accepts any Pickering 3U PXI modules. Remote control over a network enables the switching function of a test system to be located as close as possible to the target equipment. A Tegam 1750 micro-ohm meter was used to perform the resistance measurements on the fuses to an accuracy level of better than 0.1%. The custom LabVIEW software is connected to the Tegam unit via RS232. Figure 2 shows a block diagram of the set-up, and Figure 3 is a picture of the configured system.

Figure 3: Block diagram of the auto fuse test system

Figure 3: Block diagram of the Auto fuse test system

Figure 4: Showing the fixture with Tegam 1750 meter and Pickering’s space and cost-saving two-slot chassis containing the PXI multiplexer.

Figure 4: fixture with Tegam 1750 meter and Pickering’s space and cost-saving 2-slot chassis containing the PXI multiplexer.

The custom LabVIEW software developed by AST monitors digital inputs from the PLC and interfaces with the Pickering switch and the Tegam micro–ohm meter. The inputs indicate the operational state of the machine, for example, 'Waiting to load', Testing, etc. When a part is ready to be tested, the software activates the Pickering switch for the desired circuit and measures the resistance of each fuse using the Tegan meter. The software reports the measured resistance and compares the result to the minimum and maximum target values entered by the user. The software then checks to see if the fuses are in an acceptable range and indicates the result to the user. Data acquired from tests is automatically saved as a .csv file allowing it to be viewed in any data analysis tool and used for quality control and traceability.


The automated fuse tester allows the customer to quickly and accurately test the fuses they manufacture. The ability to quickly measure the resistance of each fuse and interface with the different hardware greatly improved the manufacturing throughput and the quality of the product. As a Pickering Partner, AST has the knowledge and expertise to utilize Pickering's products to their maximum potential, developing solutions tailored for individual customers and applications.

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