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Monitoring Device-Under-Test BlinkUp LEDs In The Factory

Avoid Relying Solely On Visual LED Checks To Determine Assembly State

In a Connected Factory, a Device Under Test’s LED may go green in any of a number of circumstances.

The LED may go green for a three-second period to indicate that factory BlinkUp was successful.

The LED may also go green to indicate that an impOS update is being downloaded and installed. In this case, the LED will remain lit for the duration of the update and this period is very dependent on the factory’s Internet connection.

Finally, the LED will go green when the DUT is blessed. This time, the LED will remain green for as long as the blessed DUT (ie. a Production Device) continues to be powered.

Therefore, it is important to note when you are planning your Connected Factory Process that you should not make assumptions about the stage at which a DUT has reached in the BlinkUp-Update-Blessing sequence from visual checks alone.

For example, do not mistake a slow impOS update operation for blessing: removing the DUT from the line at this stage will leave it unblessed and therefore unready for end-use.

The three-second successful BlinkUp indication may be interrupted as the DUT restarts to fetch an impOS update, or its ends may not be seen if the DUT firmware completes its work and blessed the unit within the three-second period.

We strongly recommend that you do not rely solely on visual inspection to determine how for a DUT has reached in the factory process. Only solid red indications should be used this way: either the DUTs tests failed, or blessing failed; either way, an assembly operator can be certain that the unit should be removed for later investigation.

For all other assembly progress monitoring tasks, please make use of factory firmware agents to receive status updates from the DUT and to report them: for example, to relay a message to the agent of an imp-powered display on the line, or to action an assembly line event such as power-cycling the DUT in readiness for BlinkUp from a second fixture.