Everything worked just fine yesterday. Now, your data is way noisier than it should be. Or, it’s offset by an odd amount. Did a colleague change your code? Does your instrument need repair? What are the chances that all your DUTs today truly have the same issue? What changed?
Lab experts may be able to visually inspect systems for a high-level attempt at detecting changes, but bent pins or internal cable failures are still too difficult to detect this way. Tampering with a test station that should already be working fine is nerve-racking as well because noble intentions here could cause new problems, especially when insertion counts are limited. This holiday season, we’re thankful there’s a better way.
The key here is to verify your system’s physical setup at the start of a test to detect these common ATE connection issues early but remain minimally disruptive to the test itself. To do this, we recently introduced CableSense technology to certain NI PXI oscilloscope models by incorporating a pulse generator behind our oscilloscope channels. Using principles similar to a traditional time-domain reflectometer (TDR) on a real-time oscilloscope within your test system, you can detect changes from a golden setup without having to alter connections themselves.
Using the CableSense feature, impedance (or reflection coefficient) is characterized across the entire passive electrical path from your PXI chassis to your DUT, accounting for adapters, switches, receivers, and ITAs along the way. After setting your tolerance limits and saving a mask for a known good setup, comparison logic detects both major failures like loose cables or bad relays, as well as minor failures like incorrect cable types or lengths. You can automate this check at your preferred frequency—maybe once every morning, or for long-running, critical tests, once per DUT. By tailoring the masks to your own tolerance for change, you ensure the repeatability you need to prevent false failures.
“Cable failures are one of our customers’ biggest pain points,” said Bill Driver, senior product manager at NI.
“They’ve relayed horror stories to us about needing to come in to work on weekends, one in particular on Christmas Day, when systems were urgently down. Often the fix comes down to one elusive, bad connection. This CableSense feature will only add a few milliseconds to the start of a test, which customers have indicated is worth the confidence of not losing a whole day in production.”
Going down the wrong troubleshooting path is not only frustrating but costly—your whole team’s project can get pushed back another day. Every time you miss a deadline because of a last-minute issue, you tell yourself it’s the last time a silly and avoidable mistake slips through. But, until now, how could you really be sure?
The simplest, although least effective, route is to ignore the possibility of electrical path failures until necessary (or, until they’re already urgent). For additional peace of mind, some organizations may routinely replace cables before needed or schedule downtime for connection health verification using an external TDR. Granted, frequent replacements require extra budget, and external TDRs take extra time given that each test point must be disconnected from the test station and reassembled after verification.
CableSense technology can help mitigate overall risk by catching setup changes early and qualifying the integrity of the measurements that follow, all without disrupting your typical workflow thanks to automation. Whether you’re trying to be first to market, or just stick to a strict schedule, we can all agree that you don’t have time for downtime.
If you’ve been good, go ahead and add CableSense technology to your holiday wish list. It’s definitely at the top of ours.