A large Western NY Company required a 10 position automated test station for a new product line they were developing.
They required multiple test stations to be distributed throughout the manufacturing floor, and each test station could
have a slightly different “personality” (i.e. configured to test only a particular model, or a combination of models).
Their new product (DUT) has highly sophisticated electronics and contains many on board sensors. Any communications
with the device was through an Ethernet based XML protocol. In addition to controlling the DUT’s onboard controls,
the automated test software would also need to control various environmental controllers, such as external gas
pressure and valve controllers.
The operator would need the ability to load up to 10 devices on a single test station, where each device can be a
different model. All of the DUT’s would be tested simultaneously. Additionally, each model’s test specifications
could be different, like having different configuration settings (i.e. gas type) as well as different test limit
values. To summarize:
- A single 10 position automated test station can test up to 10 different device models simultaneously
- Each model can have different test configuration settings, and different test spec limits
It was clear from the challenge presented that that the automated test system should follow a test executive
software architecture, where test steps are decoupled from the actual application, and are executed in a test
sequencing engine. The automated test system solution provided by MAS was based on this model. In general, a test
executive provides the ability to manage test steps, in this case 9 unique steps. More importantly, it provides
a framework to handle multiple instances of the same test step in a configured test sequence. For example, a gain
test step might be required at various points throughout the test sequence, where each gain step might have
different settings and spec limits. Rather than creating two separate gain tests, a single gain test is with
configurable parameters (i.e. settings and spec limits).
Because of the distributed nature of the test stations, a centralized enterprise database system was used in
the design. The central database kept track of each test station on the production floor (where each test
station can have up to 10 DUT’s), all of the model test sequences, test steps, test settings, test limits, and
final test results. Additional system settings were also stored in the database, accessible by all test stations
throughout the manufacturing environment.
The application was architected such that additional test steps could be easily added in the future.
The combination of a series of test steps would create a test sequence. The test sequence was then
associated to a specific model. A sequence editor was developed allowing a user to create test sequences.
The editor also allows the user to configure each test step with unique settings and spec limits.
Running a test requires that the operator load all of the devices to be tested on the test station and scan
each DUT’s serial number, which contains the model information. The test station then queries the database
to recall the correct test sequence for each DUT the operator loaded. The software then begins executing
the test sequence, providing a real-time status update as each test step on each DUT is completed. A typical
test sequence can run up to 8+ hours, so it was very important the software be able to run autonomously,
with little interaction from the operator.
Upon completion of the test sequence, the software logs all the test results to the database and
presents the user with the final results report for review.
Some additional technical highlights:
- A manual diagnostic screen was developed to manually control gas valves and pressures
- A National Instruments cDAQ USB chassis was used to independently monitor 10 temperature channels and control 10 heater relays
- All settings (machine and recipe) were saved in SQL Server database, with recipe versioning built-in
- Application was built using LabVIEW, and Object-Oriented technology