12-16-2010 11:56 AM
We need to make a current measurement for at least 5 minutes and average the data. Can the 4071 do this? It looks like the maximum conversion time is 149 sec, but I'm not sure if there's a way to get around that when averaging.
12-17-2010 11:13 AM
Thanks for posting! If you have a static signal that you're trying to measure for that long I would just recommend taking many 7 1/2 precision measurements and averaging them afterwards. I modified the Cont Acq & Chart Multiple Samples VI (Help » Find Examples » Hardware Input and Output » Modular Instruments » NI-DMM » Multi-Point Measurements) to accept an acquisition time input (see attached). Below is a screenshot of the VI. Hope this helps!
12-20-2010 07:17 AM
Thanks. Unfortunately I forgot to mention that the signal has some spikes in it that we need as part of the average. We're thinking we'd need to sample at about 10K to catch them.
12-21-2010 03:00 PM
If you want to sample that quickly you're going to have to set your precision to 4 1/2 digits. This has to do with the aperature time required to make a measurement at a specified precision. You can find more information on the 4070 by going to Start » All Programs » National Instruments » NI-DMM » Documentation » NI Digital Multimeter Help » Devices » NI 4070 » DMM Measurements. You'll find this spec in DMM Measurement Defaults. Hope this helps.