Issue Details

We have a question regarding the reliability of our Switch Matrix module (PXIe-2532B).

1. If one of the relays is stuck in a position (for example, in an open condition), how can we identify it? I recall that when a relay was broken, the relay status sometimes showed incorrectly.

2. What methods do we recommend for ensuring the correct status of the switch module? Do we have any methods to check the status of switches even if they are broken? Do we need an external method?

3. If the customer is using this card for critical testing and does not want to take any chances with the reliability of the connection, what recommendations do we have?

Solution

1. The PXIe-2532B lacks a built-in self-test feature. The relay status reported is the "intended" state, based on what the logic thinks it should be, but it does not reflect the actual physical state of the relay. To verify or identify a non-working relay, you need to measure its state from the IO signals.

   Customers who need to verify the operation of each relay must use an external fixture. One method is to use a known-good DUT (Device Under Test) with the switch, attributing any test failures to the switch instead of the DUT. Alternatively, a custom fixture can send stimulus signals through the switch as it operates, checking whether paths are open or closed.

   While the PXIe-2532B lacks a self-test feature, cards like the PXIe-273x have built-in features and can use the Switch Health Center to verify if relays are operating correctly outside of the customer's test sequence.

2. For the PXIe-2532B, you will need an external method. One approach is to use a DMM connected to the row signal jumpers in the TB-2640B. Then, you can iterate through a list of paths to check each relay.

3. If reliability is critical, the customer may want to consider a solid-state relay like the PXI-2533, PXI-2534, PXI-2535, or PXI-2536. These relays do not have mechanical movements, resulting in much higher reliability. Alternatively, the reliability requirement could be met by checking functionality before and after the test sequence. This can be done with a setup-specific method or by using PXIe-273x matrices, which have a Switch Health Center to verify proper operation before and after the test sequence. However, the Relay Health Center expects the cable to be disconnected and reconnected without a built-in process to verify the cable connection, and electromechanical relays do wear out after extensive use.

   If early failures are occurring with the PXIe-2532B, customers should check their signals to ensure they are not overstressing the relays. They can also characterize the relay lifespan in their application and plan to replace the relay modules on a maintenance schedule.