PXI DAQ card and DMM card

[JedRetherford]

curios,

After looking over your last two posts, I have a few more pieces of information for you. First off, in response to your last post, where you asked:

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@curios wrote:
If the ranges of voltage need to be measured is between 0 to 130VAC and 0 to 50VDC,
the ranges of current need to be measured stay within 0 to 70Amp AC and 0 to 600Amp DC. Do I still need to connect voltages and current to be measured to the respective transducers (or the voltage sensor / current sensor) and the have the signal pass through the SCXI analog input (for isolation)?

There is a question if the signals stay within the maximum and minimum ranges of dmm, could I still connect it to the transducer in the first place?

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Any signal that falls within the ranges of the DMM's capabilities could be measured directly with the DMM. You would not have to run a signal through SCXI if it falls within the DMM's specifications.

That being said, I want to reiterate, National Instruments does not have any hardware available to measure the type of amperage that you are posting about. 70 Amps AC and 600 Amps DC are too large to be measured by the hardare that National Instruments has available.

After looking over your list of needs, it seems likely that a PXI-4070 would be capable of measuring the types voltages and resistances that you are interested in, and when paired with an appropriate switch/switches, a DMM may be able to handle all the voltages and resistances you are interested in. (But not the current measurements).

Finally, I have a suggestion for you. After looking at your list of needs, I realized that the type of system you are trying to set up is very large and complex. Speccing out this type of system in a forum like this one, tends to be slow moving, as it is hard to clarify the finer details of the system. To finish specccing out this system, I feel that you would be best served by contacting your local NI Field Sales Engineer. Your local engineer would be able to come and meet with you and help you pick out appropriate hardware and software for your system. If you don't know your local engineer, call 1-800-433-3488 (in the US & Canada), and someone will be able to put you in contact with the appropriate person. If you are outside of the US/Canada, then please post your location, and I will find the appropriate contact information for you.


Regards,
Jed R.
Applications Engineer
National Instruments

[labview1958]

Is the DMM in question a virtual or a real instrument. I believe high currents and voltages will damage the DAQ card.

[zneijk]

curious,

I'm not understanding 100% what you wan't to do but a suggestion for the current measurements:

Use a "current shunt", and measure the current as a voltage and scale into Amps (I=U/R !).
However you may need multiple number of shunts depending on:
- the test level
- AC/DC-measurement
- the accuracy you need.
Guildline supplies both AC & DC-shunts with high accuracy. (http://www.guildline.com/metrology.htm)

With this method you will only need to do voltage measurements, and will not need to worry about high currents.


The suggestion for voltages > max range:
- use another DMM (PXI-4070 has been mentioned in previous comments, I believe there's a new PXI-4071 with +/-1000Vdc range (700Vrms)
- use a voltage divider, may however give phase delays ... depending on divider and input impedance ...

I'm using Hewlett Packard's HP3458A (GPIB) myself with specifications like the 4071.
If there's gonna be a PCI-4072 I might consider test it.

[RossC]

zneijk,

Thank you for sharing your expertise with curios!

Just so you know, we do currently offer a PXI-4072. It is similar to the PXI-4070, but it also adds the ability to read capacitance and inductance. Refer to the Digital Multimeters product page for more information about our PXI DMM offerings. Have a good day!

Sincerely,

Ross C
Applications Engineer
National Instruments

[labview1958]

I have set up an equipment to sent a pulse through the 6025E DAQ card. I want to measure the number of pulses per second and then multiply by 60 to find the RPM. Where can I get a tachometer.Vi to measure the pulses? Can you help?

[JedRetherford]

labview1958,

I just noticed that you jumped in on this old thread.

It's probably hard for this forum to find your post, as it is buried at the end of another thread. You would probably have better luck in getting responses to your post if you made a new post on the Multifunction DAQ or the Counter/Timer Discussion Forums:

Multifunction DAQ Discussion Forum

Counter/Timer Discussion Forum

I hope that helps with your issue.

Regards,
Jed R.
Applications Engineer
National Instruments