Making PXI-4060 and PXI-4065 hardware compatible

[Nilsta]

We have got problem when been forced to substitue the PXI-4060 DMM with the newer PXI-4065.

(4060 is going out of market)

The problem is hardware related,  (software works fine WinXP/LabView7.1)

Both 4060 and 4065 has 4 connectors  Hi, Lo, Sense+  and Sense -

There is no compability problem when measuring Volt or resistance,

but the problem is for current measurements.

Thats because the newer 4065, must measure current between the Lo and Sense+

connectors (for 4060 between Sense+ and Sense-)

See attached picture for better understanding the hardware problem between 4060 and 4065

To make the problem clearer, we uses 2 SCXI chassis with multiplexors, switches, ....

Earlier had we 2 common mux lines going to the 4060  (one to Hi and Lo, the other one to

Sense+ and Sense-).

But for the 4065 DMM, we need 3 mux lines,  (the 2 as in the 4060 case and now a mux line

to Lo and Sense-)

Now for the question.

We are not able to borrow mux capacity from the SCXI, so the solution is to buy a extra PXI relay board.

We want to maintain only 2 mux lines up to DMM in the system,  we need therefor to relay the Sense- connector to

Lo connector when we are going to measure current.

The question is:  Is it allowed to connect Lo connector and Sense- connector with a relay, when measuring current?
                            Or will the DMM be damaged inside, when Sense- and Lo are connected at current measuring?

[Alex A.]

Hi Nilsta,

I know you had been working with Andreas on this issue and I think I can clear up your question here.  The NI-4065 has internal relays that connect/disconnect based on the type of measurement you are trying to take. So having the Sense- still connected does not cause any harm to your DMM.  The current all goes to the correct lines.  I actually tested this setup and confrimed the application first hand to confirm that measurement values would not be incorrect. Hope this clears up the question.

Knowledgebase: Do I Need to Disconnect the Voltage Source When I Make a Current Measurement on a DMM...