Remote Voltage Sensing Connections

[chiuyu]

Hi

I tried to use create a VI that can calculate the efficiency of a chip.  I used Agilent E3648A to force the voltage at the input and use two DMMs to measure the voltage and current at the input.  Then, I use a Keithley 2400 to load current at the output and measure the voltage at the output.

My VI runs ok but it is not sencing the voltage at the input.  I brought the S+ and S- from the rear of the power supply and connect them to the input and ground respectively.  When I ran my VI, I expected to read some voltage a little bit higher than the voltage I forced.  For instance, I input 8V and I expect to read 8.2V at the input.  My VI only reads 8V or 7.99995V when I ran the VI.  When I take the measurement manually, I could read 8.2V at the input.

Is there anything wrong with my VI? 

Thank you for your help.

[Robert M]

Hi chiuyu,

Your VI isn't doing the voltage reading, it is only going to display whatever information is sent back from your device.  It sounds like your device is reading 8V or 7.99995V and telling LabVIEW that's what it's reading.  You may want to check your setup and your DMM.  You could try having your device read some other known voltages and see what your VI displays.  It could be that there is an offset, or your device could be reading something totally wrong.

Hope this helps,

[Dennis_Knutson]

I looked at this and I'm confused too. If you have the power supply remote sense turned on and the remote sense leads are connected at the UUT, I'm not sure why the voltage in to the UUT would be anything other than the 8.0 volts you've programmed the supply for. Anything else would point to poor regulation by the power supply.