Accuracy?

2000, 2001, 2002, 2010, 2100, 2110
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jiffyjeff
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Accuracy?

Post by jiffyjeff » October 28th, 2015, 4:05 pm

Hi, I wanted to know the accuracy of my measurements. My instrument is a 2100 DMM

My code is as follows:

CURRent:DC:NPLCycles 0.02
MEASure:CURRent:DC?

The first line I included because I wanted fast measurements. This accomplishes that, correct?

I saw the specifications - for my device but these were for measurements conducted at 1 PLC. The manual does not explain the effect of bringing down the value of PLC. How would I calculate this? Or is there another table I can look up? Or am I expected to measure myself?

Thanks.

brian.d.smith
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Re: Accuracy?

Post by brian.d.smith » October 29th, 2015, 3:08 am

The customer spec is the definitive document and is attached below. Fastest speed reduces accuracy.
SPEC-2100 (C - Sep 2011)(Customer).pdf
(78.32 KiB) Downloaded 873 times

jiffyjeff
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Re: Accuracy?

Post by jiffyjeff » October 29th, 2015, 7:33 am

Hi,

Thank you. Yes I saw that document. However, as I mentioned, the specifications are for measurements conducted at 1 PLC. Yes, I expect that accuracy will decrease with faster measurements, but my question is: by how much? Is there someway to estimate it?

-jj

Dale C
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Re: Accuracy?

Post by Dale C » October 29th, 2015, 11:24 am

0.02 PLC setting is the fastest setting for the Model 2100.
This is 4 1/2 digits. Which means a resolution of one out of 11,999.
This is just the resolution. the accuracy is specified at 1PLC as you mentioned.
But the accuracy at 0.02 PLC has not been specified.
As an estimate I would say it is about 0.5% or 100 times less accurate than the 1PLC setting.

jiffyjeff
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Re: Accuracy?

Post by jiffyjeff » November 15th, 2015, 1:19 pm

Thank you. Could you explain how you arrived at this estimate? I'm not familiar with the impact of integration time on the accuracy of an ADC.

Dale C
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Re: Accuracy?

Post by Dale C » November 16th, 2015, 6:04 am

Basically at 0.02PLC this is 4 1/2 digits.
So I lopped off one digit for the accuracy.
Instead of 0.05% it is 0.5%.
This is an estimate. There is no data to back this up.
The absolute best it could be is 1 out of 12,000.
One out of 1000 is 0.1%.
One out of 10,000 is 0.01%
The A/D runs faster but not enough time to realize the full accuracy at 0.02 PLC.

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