NI DMM 4070 to measure voltage in microsecond scale

[thanhvan]

Hello everyone,

Would you please help me with two questions:

Can DMM 4070 used to measured and analyse the ON/OFF time of a signal with amplitude around 3V, required resolution is in microsecond.

Scan DMM 4070 at 1.8MS/s resulted smaller voltage than using its test panel, what should be a reason?

Thanks in advance

thanhvan

[ShalB]

Hello thanhvan,

Thanks for your post on the forum.

To answer your first question, the DMM 4070 would be able to accommodate a maximum of 5.5V. The threshold for a high (ON) is 2.4V and for a signal of amplitude 3V that means it is a high. However, for the low state (OFF) make sure that the voltage is below 0.4V. Have a look at page 13 on the the specifications below:

http://www.ni.com/pdf/manuals/371304g.pdf

Regarding your second question, can you please clarify me on that please.

Many thanks,

[thanhvan]

Hello ShalB,

Thank you for your reply.

When I used the test panel in MAX for DMM 4070 to measure the voltage, it showed 3V (input resistance 10MOhm), which is corrected with our device.

However, using DMM4070 in LabVIEW and scan the signal at 1.8MS/s, although I can see the waveform as expected, the value is only from 0.2V to 1.5V (waveform peak to peak)

My signal is a DC voltage, average value of 3V, oscillating amplitude of +-300mV around mean, frequency of 1kHz.

By the way, is it true that we can not set input resistance >10GOhm when using DMM waveform read?

Regards,

thanhvan

[ShalB]

Hello thanhvan,

Thank you for the clarification.

I would suggest that you go to the NI Example Finder on LabVIEW and use the Measure DC Volts.vi with your signal. Make sure that the range is set correctly, such that it is close to the value of your signal. Let say 3V for example. You should be able to get the correct voltage reading. If this does not work, if you could please send me your codes and I will have a look.

Regarding the input resistance, it is true that it cannot go above 10 GΩ. Have a look at the following link for more information.

http://zone.ni.com/reference/en-XX/help/370384N-01/dmm/dcv/

Thanks,