Digital Multimeters (DMMs) and Precision DC Sources

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pxi-4071 constant current

We use 4110 voltage source for current measurements on pxi-4071. We supply high-ohm (1.5 GigaOhm) resistor with few volts and measure current on 4071. All cables are shielded on ground of 4110 voltage source, but cables are about 5 meters long. What can be reason for constant current 5 nA at zero supply voltage? We don't know whether it software or hardware problem, and i already asked this question in LabView forum, autozero enabled in max doesn't help. Could be a reason bad shielding of ground in pxi-4110 voltage source

?

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I would focus on the hardware side initially. I would try the following steps.

1) Make a current measurement on the 4071 with the inputs open to see if there is an offset. If so we should look into the DMM configuration.

2) Connect your cabling and/or resistor without the 4110. If this adds the offset then it seems to be shielding/noise related.

3) Connect the cabling and/or resistor to the 4110 with the output disabled. If this adds the offset then it could be ground related or also related to an offset in the 4110 output.

 

Steve B

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Hey Alyast,

Can you also verify what range you're in?


Thanks!

National Instruments
Precision DC Hardware Engineer
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Hi I need someone who can help me, I'm doing a program I receive my myDAQ analog signals, the problem I have is that you as connecting a combox to my program, I want is that when you make the selection of AC voltmeter, the program will go to the 7.3 multiplier stage, or when I select Voltmeter DC is to be a multiplier of 9.8, please need help.

 

Hola necesito a alguien que me pueda ayudar, estoy realizando un programa que recibo señales analogas con mi MYDAQ, el problema que tengo es que no se como conectar un combox a mi programa, lo que quiero es que cuando haga la seleccion de voltimetro AC, el programa se vaya a la etapa de multiplicador por 7.3, o cuando selecciono Voltimetro DC se vaya a un multiplicador de 9.8, por favor necesito ayuda.

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Hi Aleman2012,

 

In order to make sure that the forums are searchable and that your question is easily found, I would recommend only posting the question one time. Also, since this is a forum for DMMs and power supplies, it would be best if we continued from this thread that you had been receiving help in already.

 

Regards,

 

Jason D

Applications Engineer

National Instruments

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