Automated High Voltage Defibrillator Testing Using NI LabVIEW FPGA and Intelligent DAQ

Author(s):
David Hakey - Medtronic, Inc.
Patrick J. Ryan - Medtronic, Inc.
Johnny Maynes - Medtronic, Inc.

Industry:
Life Science, Electronics

Products:
Data Acquisition, PXI/CompactPCI, FPGA Module, Digital I/O

The Challenge:
Providing an automated high-voltage (HV) defibrillator tester that can test 12 HV defibrillator modules independently, as well as test different product types and reduce overall test time.

The Solution:
Creating an asynchronous environment using National Instruments LabVIEW FPGA software and NI intelligent data acquisition (DAQ) hardware in which all 12 modules can run autonomously and each module has an independent communication port.

The Test Engineering Group at Medtronic was challenged to provide an automated HV defibrillator tester solution with 12 test modules that can independently test one to four different product types while reducing overall test time. Using LabVIEW FPGA and National Instruments intelligent DAQ hardware, the team dramatically increased module communication speed from 20 KHz (parallel port) to 1.7 MHz (FPGA), resulting in a reduction in overall test time.

The previous manual system ran 12 modules synchronously using parallel port communication and only tested one type of HV defibrillator, with a test time of 135 minutes for 12 devices. The new automated system can run 12 modules asynchronously with FPGA digital I/O communication, testing up to four different product types with a test time of 48 minutes for 12 devices. A reentrant test sequencer and test program independently control each test module so that each device starts testing when directed by the automation device handling system. A test executive PC coordinates the automation device handling system and HV defibrillator test system as a whole.

Test Automation

An AeroSpec test automation handling system is responsible for picking a device under test (DUT) from one of four input trays, reading the DUT serial number via optical character recognition, loading and unloading the DUT into one of 12 test modules, and placing the DUT in one of 12 output trays based on test results. Four different products can be configured on the four input trays, and each tray can hold up to 20 devices.

The test executive system is the master controller, providing the user interface, directing test module loading and unloading, and instructing the test manager to perform the HV defibrillator test on the device or devices loaded in the test module.

The test manager determines the products capable of being tested and relays this information to the test executive so production operators can select the products to test. The production operator then loads the products per the system configuration and begins the test, and the test executive commands the test automation handler to load a DUT into a test module. Once the DUT is loaded, the test executive commands the test manager to start testing on the specified module. The test executive and test automation handler continue loading the remaining DUTs for the duration of the test sequence, while the test manager commences testing each DUT. The test manager dynamically calls up to 12 reentrant test sequencers, which then dynamically call reentrant independent test programs. The test manager launches each test program when directed by the test executive.

The system manages all test modules and DUTs within the LabVIEW graphical programming environment. Each test module has a static set of attributes whose values change depending on product type, test phase, hardware configuration, and other process attributes. Each test instance remains in memory until closed by the test manager when the test on the given DUT completes. The test manager monitors the test status and informs the test executive when the DUT completes testing by providing the test pass/fail status. The test executive then commands the test automation handler to unload the DUT from the module and place it in an output tray. The cycle repeats with another DUT being loaded into the vacant module for testing. The DUT load, test, and unload cycle happens independently for each of the 12 tester modules. The requests for loading and unloading are queued up by the test automation handler in the order received.

Two National Instruments PXI-7811R modules control all communications to and from the test modules and DUTs via serial communications (SPI) and JTAG, respectively. Each NI PXI-7811R module runs the same LabVIEW FPGA code, but has a separate semaphore and NI-VISA resource that controls access to that module.

A test sequencer controls DUT testing by dynamically calling a test case from the test program. Because there are up to 12 reentrant or independent copies of the test sequencer and test program resident in memory, there was a compromise between system performance and having all subVIs or subfunctions reentrant. Only those subVIs that proved to be a bottleneck or contained functional globals where made reentrant. This solution optimized performance while minimizing the overall system memory usage. All of the test sequencers and test programs use the same FPGA, so the system uses semaphores, or tokens, to control access to each PXI-7811R module.

All of the VIs that require access to the FPGA code utilize semaphores. Each FPGA target has an independent semaphore, which allows one module in group A (1 through 6) to access the first FPGA target and one module from group B (7 through 12) to access the second FPGA target almost simultaneously. Each FPGA interaction is very short – on the order of a few milliseconds – so this method works very well in allocating the FPGA resources supporting 12 competing programs. There are approximately 600 FPGA interactions per test program per module. The FPGAs are able to handle all of this traffic and are instrumental in allowing the system to run 12 modules asynchronously at high speed.

 

For more information, contact:

David Hakey, Medtronic, Inc.

2343 W. Medtronic Way

Tempe, AZ 85281

Tel: (480) 929-5521

Fax: (480) 303-4724

E-mail: david.l.hakey@medtronic.com

 

 

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