"Two PXI-based systems met the entire production throughput and saved more than 60 percent on initial investments. With the ATEs’ compactness and capability to test all boards, two test lines managed the entire testing rather than of four resulting. This saved more than 60 percent shop-floor space, which is always a premium."
- K. Swaminathan, Soliton Automation Private Limited
The Challenge:
Developing a cost-effective test system for testing four different component boards with different proprietary software and hardware interfaces in a PC-based ultrasound machine.
The Solution:
Designing a test system using the ultrasound machine back-plane as the test fixture and using a PXI-based system running a customized LabVIEW application to test the four boards and reduce costs and development time.
Author(s):
K. Swaminathan - Soliton Automation Private Limited
M. Mohan - Soliton Automation Private Limited
V. Arunachalam - Soliton Automation Private Limited
Our customer is a global leader in the manufacturing of ultrasound machines for medical applications. New age ultrasound machines are PC-based with proprietary hardware and software that provide powerful functionality to the machine. A typical ultrasound machine consists of various boards that communicate with one another through a back-plane and the control PC through a proprietary control interface. Each of the boards serves specific functionality, and we tested these by feeding various electrical signals or software commands and verified the outputs using instruments and software. Our customer wanted one integrated automated test equipment (ATE) system to test four printed circuit boards (PCBs) that go into the ultrasound machine.
PC-Based Ultrasound System Description
A typical PC-based ultrasound system consists of various component PCBs that perform different functions. A probe generates and receives ultrasound waves, which process to yield vital information about the test subject. The probes connect to a connector board with provisions to accept different types of probes. A transmit board generates high-frequency waveforms and sends it to the probe. A receiver board receives the reflected waveforms from the probe. A beam former controls transmit and receive patterns, while a proprietary control board provides the interface to the ultrasound machine PC from the hardware. The boards mount on a back-plane that provides the link between the various components. Proprietary software performs all the required communication to the various boards for individual control of the various parameters.
During manufacturing, the boards are assembled and tested before being integrated into the ultrasound machine. We test the board components two ways:
1. By sending physical signals and observing the resultant signals for different characteristics
2. By communicating with custom electronic components, such as FPGA registers and programmable memory chips
Our customer wanted one system with the flexibility to test all four boards, and two such test systems to meet the production throughput. We chose a PXI-based architecture for the ATE because it is better suited for the manufacturing environment, and a PC may not reliably handle four cards, including the proprietary control board that has a PCI interface.
With a MXI-based design, we effectively utilized PXI while retaining the capabilities of the PC needed for interfacing with the communications and control board. We used the NI 5401 PXI function generator to provide various signal inputs for testing and a NI 5112 digitizer to measure the signals and analyze the waveforms. We also used the PC to control a proprietary switch unit provided by the customer through a serial interface.
We designed the ATE to test all four boards. We used the back-plane of the ultrasound machine as the fixture and used calibrated ‘reference’ boards to test the manufactured boards. For example, while testing connector boards and reference boards of the remaining receiver, we transmit and beam former boards fixed on the test fixture. We interchange the standards when we needed to complete the testing had to be done for a different type of board. With this arrangement, we effectively utilized two ATEs to test four different products in two test lines rather than four separate test lines.
Developing Customized Applications with LabVIEW
We used LabVIEW for the customized application development because it offered excellent tools for rapid application development and deployment. The graphical user interface provided the standard operating procedures, as well as with visual aids to guide the user. For testing, we fed the testing involved feeding different test signals to various positions in the boards through connectors. We made the connections through the proprietary switch unit. The switch unit had a keypad interface for manual switching. While testing, the user selects the appropriate channels and feeds the test signal from a function generator and observes the waveforms using a scope. The ATE automated this switching through a serial interface. We programmatically controlled signal parameters in the function generator and complete the measurements with the PXI scope. We perform custom requirements, such as burst measurement with ease in LabVIEW.
A challenging part of development was interfacing with the proprietary software used for communication between the ultrasound PC and the boards. We loaded this software into the test PC and successfully established communication with the proprietary libraries. We used these function calls in the application software to communicate directly with the boards. Testing involved communication with FPGA and memory registers, board-level flash memory, and data retrieval through proprietary bus interface. We implemented all communication with the various components and tested them successfully. The ATE generated customized test reports, and the manufacturing test information was available over the internet in HTML format to different manufacturing locations.
Reducing Initial Investment by 60 percent with PXI
Using our PC-based system, we reduced test time form three hours to 12 minutes, including initial connections. Now, one person can manage two ATEs to meet production targets, rather than the four operators that the manual system demanded. The PC-based system also delivers reliable, repeatable measurements with automatic report generation, as well as easy to use visual aids to assist users during initial setup. Two PXI-based systems met the entire production throughput and saved more than 60 percent on initial investments. With the ATEs’ compactness and capability to test all boards, two test lines managed the entire testing rather than of four resulting. This saved more than 60 percent shop-floor space, which is always a premium.
Our customer wanted a cost-effective system developed quickly to meet deadlines. We provided a value-added system with the PXI-based system, and LabVIEW helped us develop and deploy our application on time, earning us another happy customer.
For more information, contact:
K. Swaminathan
Classic Towers 1547 Trichy Road Coimbatore - 641018, India
Tel: 91 (422) 302374 - 302371
Fax: 91 (422) 302375
E-Mail: achinna@solitonautomation.com
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