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Testing Smart Meters/AMR - ZigBee Automated Manufacturing Test Solution

ZigBee Automated Manufacturing Test Solution for testing Smart Meters/AMR

Objective


To develop a high speed, reliable, cost effective and fully integrated test bench capable of performing RF tests on multiple ZigBee/802.15.4 devices (smart meters/AMR) simultaneously with test times fewer than 3 seconds to validate devices in the production line.

Client requirements & challenges faced


The product has been designed to provide the following requirements:

  • Fast testtimes: Completely test any device within 25 seconds (RF +PCB tests).
  • Automation of RF and board level tests.
  • Maintaining a very high device production throughout shop floor times.
  • Minimize radio interference at each test bench.
  • Perform PCB tests and barcode scanning for each device-under-test (DUT).

Solution


SeaSolve’s ZigBee production tester offers speed and accuracy with various RF Chipsets from leading manufacturers and integrates with the National Instruments’ RF test equipment. The test solution is able to control the ZigBee device-under-test and is capable of carrying out board level measurements in addition to achieving test automation. Measurements and results are reported and saved in HTML format. Reported results are stored automatically into an integrated database from within the solution.

Main Screen of Controller Software

KEY APPROACHES TO CHALLENGES

1.

Automation of RF tests

  Leveraging past experience in automated compliance testing (aCT), SeaSolve is able to communicate with the device-under-test (DUT) through the TCP/IP interface. Commands sent through SeaSolve’s application software to the device enable it to either transmit or receive packets continuously. These ‘test modes’ are used to control the DUT through the software itself while running transmitter and receiver tests sequentially. This form of test automation (for the RF tests) eliminates the need for manual operator intervention during the tests, thus saving cost and time.

2.

Maintaining high device throughput / production

  Combining test automation with fast test times, the SeaSolve/NI test bench is able to reliably test up to thousands of devices per day. The detailed explanation of this section is given below.

3.

Completely test any device within 20 seconds (RF tests)

  SeaSolve’s test APIs that are employed in the main software program use customized algorithms that enable measurements to be taken in several milliseconds. SeaSolve’s ZigBee manufacturing test solution can test any given DUT in parallel for RF (PHY) standard-compliance between 10-25 seconds.

4.

Minimize radio interference at each test bench

  RF shielded boxes, designed specifically for production line testing, were used to house the DUT and RF interface. The shields also hold the barcode scanner used to identify each DUT during the testing phase. The entire RF shield and housing is hereby referred to as the ‘test fixture’.

5.

Reporting and Database Integration

  The tester saves detailed test reports in .html format for future reference. These reports can also be saved to a shop floor database. The database saves information such as DUT ID, DUT Serial Number, Execution Times and Pass/Fail results of various tests for different DUTs etc.

Miscellaneous Features


  • Reduces investment costs to a great extent.
  • User-friendly software interface.
  • Provides an excellent device production throughput.
  • Results are reliable and repeatable.
  • Customization of test bench software and hardware available.
  • The platform supports testing of frequencies up to 6.6 GHz.
  • Highly versatile - can be utilized in the design validation and/or production test processes.
  • Verification of chipset/reference/prototype designs for standard compliance.

Benefits and Methodology

SeaSolve’s Manufacturing Test Solution has been designed to provide the following specialized features.

SeaSolve recently provided a full-fledged Automated Manufacturing Test solution to a client using an Ember EM-250 chipset (controlled through LAN). The solution provides complete control of the ZigBee device-under-test through a script file (allowing the user to employ various test configurations) to achieve very fast test times and test automation. It is also capable of carrying out board level measurements such as voltage and current measurements. The main highlights of the Automated Tester are:

1.

Very Fast Test times

 

The Test Solution is designed to minimize measurement times, hence reducing the overall test times. The tester takes not more than 20-25 seconds to perform all the tests, which includes scanning of the DUT, performing various Transmitter, Receiver and Board levels tests and giving out detailed tests reports. The following tests are typically carried out by the solution:

  1. DUT Scan and Validation
  2. PCB Tests
  3. Error Vector Magnitude (EVM)
  4. Power Spectrum Density (PSD)
  5. Occupied Bandwidth
  6. Center Frequency Offset (CFO)
  7. Receiver Sensitivity

All the tests are customizable depending on client requirements. As soon as the DUT is placed inside the test fixture (provided by the client in this case), the device is scanned, validated and tested for the measurements mentioned above. The tests are carried out sequentially without delay, giving Pass/Fail results instantly and not taking more than 20 seconds for the whole process.

2.

Multiple device testing and user-friendly interface

 

The Automated Tester makes use of NI’s TestStand for all the software integration. TestStand is the test management software which allows testing of multiple devices sequentially or in parallel. Using Test Stand’s Auto-Scheduling and Resource locking features, the solution can test up to 4 DUTs in parallel. For example, if there are 4 DUTs that need to be tested and each of them is placed in 4 different fixtures, transmitter tests are first performed on DUT 1 (i.e. using the RFSA on the NI hardware). The TestStand interface (integrated within SeaSolve’s software) then looks for the free RFSG resource and carries out receiver tests on DUT 2. Then, as soon as the RFSA is available again, DUT 3’s transmitter tests are carried out. This process is repeated until all 4 DUTs are tested.

SeaSolve’s software offers a user-friendly interface that provides the user with an easy-to-use environment. The solution calls the TestStand-based sequence from within the software and carries out various Transmitter, Receiver and PCB tests in an automated fashion, reducing test times drastically.

Figures 1-5 below gives a general layout of the user-interface that is provided and how the tests are carried out for a particular DUT.

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Figure - 1

The software can be password protected to provide additional security. Multiple logins can be maintained for different levels of users (i.e. test engineers, supervisors, etc.)

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Figure - 2

Each DUT needs to be connected appropriately in its respective fixture for scanning before commencing the RF and PCB tests.

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Figure - 3

Clicking “OK” starts the various tests sequentially with the results (also saved in detailed, easy-to-read report formats) for each test given as “Pass/Fail” LEDs for the particular DUT.

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Figure - 4

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Figure - 5

3.

Report Integration

 

The tester saves the detailed test reports in .html format for future reference. These reports can also be saved to a shop floor database. Given below are some sample screen shots of the reports.

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4.

Device Throughput

 

The Tester, with its fast and efficient test times, enables much higher device throughput on the production shop floor.

5.

Flexibility in Hardware and Software

 

SeaSolve offers flexible hardware and software to cater to the heterogeneous nature of its client needs.

In the hardware, for example, the National Instruments’ platform allows for the addition of other hardware modules to the test bench. In this client’s case, an NI DAQ PXI module was added to the test bench for carrying out PCB measurements such as voltage and current.

In the software, if a client needs a particular test to be added, SeaSolve can customize the test sequences accordingly. The software leverages a customizable and parallel model in LabVIEW and TestStand which enables the testing of multiple DUTs independently.

Specifications of the tools used

SeaSolve’s software designed and developed for this application provides a complete test-bench solution that integrates with the National Instruments (NI) RF PXI-Express platform.

  • NI LabVIEW Graphical Development Environment (for main software program)
  • NI TestStand (used for test sequencing)
  • National Instruments PXI vector RF signal generator(s) and analyzer(s)
  • National Instruments PXI RF switch(es)
  • National Instruments PXI DAQ card
  • Jig and Fixture
  • Device under test – Ember EM250 (LAN interface) board

SeaSolve plans to continue to cultivate new businesses and work with various chipset manufacturers. We have the capability to build similar solution for other ZigBee chipsets.

SeaSolve has developed automated compliance test solution and automated manufacturing test solution for MANGO (Radio Pulse Korea) and EM-250 (Ember Corporation) respectively.