Optimizing Test Time Part 3, the Heart

In our Optimizing Test Time series, we’re looking at how cutting down test times can make a significant impact on your business. Cutting down test time does not need to mean sacrificing quality though, as we demonstrate by reviewing the key areas in which test time can be improved:

In Part 1, we talked about how test software can be optimized by using the right platform that utilizes the latest advances in processor technology and in Part 2, we show how test instruments themselves can often be optimized for better throughput.

It’s not enough, however, to have a smart brain and powerful muscles. Just as our heart provides the rhythm for our body functionality, synchronization plays the part of the ‘heart’ of the test system by coordinating the sequence of actions one after another. Almost all automated test systems require some form of synchronization between two or more instruments or switches and the device(s) under test.

Synchronization

Synchronization is important when it comes to fine-tuning test times. It is also one aspect which can be easily overlooked, because it is not very visible. Unlike test software whose code you can see and instruments which you can physically touch, synchronization happens in the background. Getting the right actions to be performed at the right times with minimal delay between each action is the heart of the matter when it comes to synchronization.

As an example, in a manufacturing line, a digital multimeter may be connected to a multiplexer switch to sequentially make measurements on hundreds of devices. This is usually set up to reduce capital costs and maximize test station utilization as opposed to having one digital multimeter per device. In a nutshell, the digital multimeter will make a measurement on one device and then switch over to the next device until all devices have been tested. Here, synchronization involves coordinating the digital multimeter to make measurements only after the switching has settled and the switching only after the measurement has been completed.

There are two possible types of synchronization - software and hardware. Software-based synchronization uses triggers generated by a test software call, while hardware-based synchronization uses electrical triggers generated by the internal circuitry of the instrument. Software-based synchronization is subject to overhead, because the software shares resources with all other applications that require processor time.

On the other hand, hardware-based synchronization relies on the triggering that comes directly from the instrument, independent of the software. That makes it an inherently faster path to take in most cases. Going back to the earlier example, instead of adding software delay to allow for the switch settling time and using software to initiate the instruments, by using hardware-based synchronization, the switch will send a trigger signal directly to the digital multimeter upon completion, completely bypassing the software overhead. This certainly speeds up the entire measurement process, potentially up to 50% faster.

Consider looking into using as much hardware-based triggering as possible to reduce test time. Although it may be a little bit trickier to set up than writing codes for software-based synchronization, it can be well worth the effort in the long run.

For more insights into optimizing test time, you can read Part 1 and Part 2 of our series. And subscribe to our blog to receive Part 4, as well as future posts about this and other test equipment-related information.