Data tracking is an essential part of the manufacturing process for automotive printed circuit board assemblies (PCBA), and it requires each PCBA unit to come with a unique serial number. The barcode reader captures the serial number and logs it to the manufacturing execution systems (MES) along with the test results and measurements.
Barcode readers commonly use serial communication ports or transmission control protocol/internet protocol (TCP / IP) sockets communication and control. Pathwave test executive for manufacturing (PTEM) supports these as serial and socket interfaces under the instrument definition. For readers using other interfaces like universal serial bus (USB), PTEM supports them through .NET framework dynamic linked libraries (DLL).
Depending on the type and resolution of the barcode labels, adjust the parameters of the barcode reader to capture the labels effectively. Work with your barcode reader’s supplier on setting the reader to support your barcode requirements. Once the reader is setup and tested, you can start on adding the test steps into your PTEM testplan.
The bench settings menu in PTEM allows you to define the barcode reader as a serial or socket instrument in your test plan. Select the instrument type and enter the parameters according to the setup of your reader as in Figure 2. We will talk about using .NET DLL in future posts.
Next, we add the test steps to send the trigger command and query the captured barcode value from the reader. The reader does require time to capture the barcode labels, so add a small delay in between the send and query steps as shown in Figure 3.
Figure 3 Send and read commands to reader with 0.5secs delay time in between.
For a testplan that oversees single board testing, you can assign the barcode value to the serial number of the device under test (DUT) directly. For a multi-board testplan that supports panelised testing, you may need to use this value to derive the serial numbers for the rest of the DUT.
Panelized boards are common in the automotive industry as the printed circuit boards in a vehicle are smaller. Electronic control unit (ECU) boards typically come in a panel of four or six boards while sensors, lighting and camera boards come in higher board count as their physical sizes are smaller. With each board in the panel bearing its own barcode label, it becomes a challenge for an automated manufacturing line to capture the physical barcodes on a multi board panel. Barcode scanning is an automated process with the reader fixed at static position along the conveyor line. The reader captures the barcode when the panel comes into its field of view. But this can only capture one of the barcodes in the panel as the other barcodes are at various positions.
To capture the barcodes of the rest of the boards in the panel, the reader, or the panel must move to get each of the barcode under the reader’s field of view. While this is achievable with a X-Y table solution, it is costly and incurs high cycle time. The solution is to capture only one barcode from the panel and derives the rest automatically.
Barcode values for each board in the panel are usually sequential. With the captured barcode, increase or decrease the value by one for each other boards in the panel. With a few lines of codes, test plan does this in less than a second with no added hardware cost.
PTEM takes care of these with the barcode generation test step. This test step takes a first barcode value from the reader and derives the serial numbers using the logic of plus one or minus one for every other board in the panel.
In Figure 5, the testplan captures the first barcode value from the reader and uses it as the input value to the barcode generation step. The setting of DUT position number in the test step assigns the input value to that DUT in the panel. In the above example, there are three DUTs in the testplan and the value captured from barcode reader is SN100. The barcode generation step assigns this to DUT#2 and creates SN099 for DUT#1 and SN101 for DUT#3. A barcode array variable holds this set of serial numbers for the following test sequences to make the assignments accordingly.
So that is all it takes to create multiple serial numbers automatically using an initial captured value from the barcode reader using PTEM.
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