Digital Multimeters (DMMs) and Precision DC Sources

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What is the expected output relay life for the PXIe-4139 states that
"Excessive connecting and disconnecting of the output can cause premature wear on electromechanical relays, such as those used by the NI PXI-4132 or NI PXIe-4138/39."

How much is "excessive"?

Which relay are you using and how many operations is it rated for?

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Message 1 of 6

I couldn't find any public documentation regarding this but I would assume OMRON or equivalent quality relays with at least 1Million cycle expectancy.

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Message 2 of 6

Yea, I am expecting it to be in the millions but I really would like something more concrete.
I can look at the board to see if I can find a P/N next time I am on premises.

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Message 3 of 6

I believe the answer is heavily dependent on the current and voltage going through the relay at the time. If you are sourcing high power, there will be arching that will cause the relay to die sooner. I've pinged others to see if they can provide more concrete estimates. Regardless, best practice is to flip the relay as little as you can or at least source 0 before you do it. Performing a reset between every test gets you a clean slate which is nice, but is usually not necessary. If you are initializing a new session between your tests then consider passing false to the reset parameter in the initialize function.

Marcos Kirsch
Chief Software Engineer
NI Driver Software
Message 4 of 6

There's a solid-state relay in series with the electromechanical one to prevent the hot switching Marcos is referring to.  In fact, there's a good chance the sense contacts will wear out before the current-carrying ones, as the lack of current flow allows oxide to build up, increasing the resistance.  The resistance of those contacts doesn't matter a lot, but it does matter.


The relay is an Axicom IM42DGR.


I don't believe the reset in initialize will flip the relay.  Output disconnect will, of course, as will self-calibration.  I believe it opens on power-down as well, but I'm less sure about that.

Message 5 of 6

Here is what TE lists for the IM48DGR



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Message 6 of 6