# Digital Multimeters (DMMs) and Precision DC Sources

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## NI DMM

Hi all,

V+ and I+ of a DMM  are shorted and connected across one end of a resistor. V- and I- are shorted and this is connected to the other end of the same resistor. Its a 4-wire connection measurement.This resistor is connected in series to PSU positive terminal. Does this connection damage the DMM  when I take Voltage and Current measurements at resistor after powering up PSU?

Can anyone help me with this?

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## Re: NI DMM

You will not be able to measure current through the DMM with that setup.  You should have V+ connected to one side of the resister, V- and I+ connected to the other side, and I- to wherever the other side of the resistor is supposed to go (ground?).  You have to do it this way since current has to be measured in series.  Voltage is measured in parallel.

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## Re: NI DMM

Hi,

Thanks for the reply.

But I want to make clear that I'm not taking any current reading. I just want Voltage readings across resistor after Power up.

My question is Will it damage the DMM if I take Voltage measurement at PSU when V+ and I+ is short?

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## Re: NI DMM

Remember that the current sense on a DMM acts as a short to a circuit.  So I am more concerned that you have your resistor shorted via the current measurement lines on your DMM.

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