08-28-2013 02:50 AM
Have one small common query.
I have a DMM connected to industrial PC. I want to measure resistence continously for 2 seconds (or n seconds or ms) between 2 points of a DUT which is connected to DMM. How to achieve this multiple value measurment using LabVIEW? How to control timings? how long each measurement might take? or will there be delay btween measurments or necessary to insert some delay? any inbuilt function will serve this task?
or what are the configurations are to be made?
08-28-2013 06:43 AM
What DMM are you using?
The simple way would to just use a FOR loop to take N readings and have a Wait(ms) inside the loop to control how long each reading takes.
08-28-2013 07:14 AM
Even I had same thought of implementing but was curious to know if any direct function calls are available to do that. DMM can be any PCI compatible.. Between, what is the difference between Single point and multypoints measurments?
08-28-2013 09:33 AM
This is why I asked what DMM you are using. If you are using an NI DMM, then the multiple point acquisition could help. Give this a good read: Multiple Point Acquisitions. If you are using LabVIEW, look in the Example Finder for "Acq & Graph Multiple Samples" for a quick example of how to setup and run.
08-28-2013 10:40 AM
Can you clarify 'continuous'? It sounds like you're doing some type of analog trimming and want instant feedback while you're cutting. Of course, this is a random guess, but whatever the application, the first goal is to determine your acceptable sample rate. Is 100S/s acceptable? 1MS/s? What kind of accuracy are you looking for? Do you need to make a 4-wire resistance measurement for improved accuracy? What resistance values are you expecting? How much current can your DUT take?
If this is in a computer, my first recommendation is the PCI-4070. Depending on the application and sample rate, your best option might not be a DMM, but rather use a FlexSMU (e.g. PXIe-4141, etc): apply a known current (or voltage) and then use old V=IR to determine resistance. This allows you to increase the test current, test speed, etc, depending on your given specifications. Let us know more details and we'll tailor a more specific answer.
Viva La Resistance