Products > Test Equipment
Rigol DP832 - Firmware list and bugs
LaurentR:
Just found time to run a full 1mV sweep of Ch3.
And the answer is... yes, Ch3 has better granularity. Eyeballing the data, it seems to have about 0.22mV granularity, which is a bit more than twice as small as Ch1. See histogram attached. I should have added axis titles, but the histogram is of the measured voltage difference between two consecutive steps (separated by 1mV, the programming granularity). The peaks show that the distance is usually around 1.045mV, and if not, most likely around 0.83mV (and extremely infrequently around 1.25mV), thus the derivation of the DAC granularity.
Note that actual absolute accuracy and linearity are much worse than this, so I don't think that this has practical applications. On my home-calibrated DP832, Ch3 stays within about +/- 1.5mV of programmed value throughout the whole sweep, which is quite good.
bson:
Nice to see some actual data!
I agree on absolute accuracy - it's good but not down to 1mV. It probably varies from unit to unit; on mine (also DIY calibrated) CH3 is ridiculously precise and always accurate to 1mV. Today though I needed 14.5V and dialed in CH1, and ended up reading 14.498. (Which is pretty damn good in itself.) Put a DMM (34465A) on it, which also read 14.498. So ticked it up 2mV to 14.502V and got 14.500V out. Nice! :-DMM
I was using one of these below to compare an Agilent 34401A (scored for $350!) to the 34465A. According to the seller, my 10V reference is 0.37ppm low. The 34465A reads it 6.7ppm high; the 34401A 24ppm high. All good enough for government work! Didn't try null measuring -- really should get myself a cheap microammeter, and maybe better leads than my $6 Pomonas, so it's not as super accurate as it could be, but I just wanted a quick ballpark check of the 34401A, relative to the 34465A... Here's the reference - highly recommend it. http://www.ebay.com/itm/10-VDC-2ppm-Precision-Voltage-Reference-Standard-Nulled-to-Fluke-732A-or-732B-/251756273626?pt=LH_DefaultDomain_0&hash=item3a9dd7dfda
LaurentR:
--- Quote from: bson on June 28, 2015, 10:44:01 pm ---Nice to see some actual data!
I agree on absolute accuracy - it's good but not down to 1mV. It probably varies from unit to unit; on mine (also DIY calibrated) CH3 is ridiculously precise and always accurate to 1mV. Today though I needed 14.5V and dialed in CH1, and ended up reading 14.498. (Which is pretty damn good in itself.) Put a DMM (34465A) on it, which also read 14.498. So ticked it up 2mV to 14.502V and got 14.500V out. Nice! :-DMM
I was using one of these below to compare an Agilent 34401A (scored for $350!) to the 34465A. According to the seller, my 10V reference is 0.37ppm low. The 34465A reads it 6.7ppm high; the 34401A 24ppm high. All good enough for government work! Didn't try null measuring -- really should get myself a cheap microammeter, and maybe better leads than my $6 Pomonas, so it's not as super accurate as it could be, but I just wanted a quick ballpark check of the 34401A, relative to the 34465A... Here's the reference - highly recommend it. http://www.ebay.com/itm/10-VDC-2ppm-Precision-Voltage-Reference-Standard-Nulled-to-Fluke-732A-or-732B-/251756273626?pt=LH_DefaultDomain_0&hash=item3a9dd7dfda
--- End quote ---
Ch3 is substantially better than Ch1. Just like Ch1, it's mostly very good (and within 1mV), but has some interesting peaks and valleys that extend to 1.5-2mV. See plot below.
That's a full 1mV sweep measured by a 34465A.
cidak:
--- Quote from: Belgarion on June 27, 2015, 09:47:45 pm ---
--- Quote from: cidak on June 27, 2015, 08:23:40 pm ---To all owners of DP8xxx. :-+
I would like to ask those who have a DPxxx Rigol it may do a test to compare if it's a problem of my power unit, or if there is a firmware bug general.
The test is the following: :-DMM
by any value set at the output (for example 1 Volt) increase the voltage of 1 mV at a time, measure the output with a DMM :-DMM external if indeed the intention output rises to 1 mV at each step, or as in my case increases 0.6 mV and the next step in a 1.4 mV (total actual doing of the two steps 2 mV). :bullshit:
So every 2 steps it the 2mV correct but to every single-step one is from 0.6 mV and the other from 1.4 mV. This is repeated alternately 0.6 /1.4 ~ 0.6 /1.4 etc.
Thanks
--- End quote ---
These are my results:
DP832 set value (channel 1)Measured on DMM1.000V1.001295V1.001V1.002326V1.002V1.003329V1.003V1.004366V1.004V1.005366V1.005V1.006410V
DP832 set value (channel 3)Measured on DMM1.000V1.000869V1.001V1.001894V1.002V1.002943V1.003V1.003981V1.004V1.005005V1.005V1.006063V
--- End quote ---
Thank you for your quick and accurate response.
Ok, your Log on measured voltages in steps of 1 mV, seems to be perfect.
So I hom a problem it seems, because as explained initially each time increment of 1 mV ago the first increase 1.3mV and 0.7mV per second increase.
I calibrated DAC and ADC repeatedly my DP but the error is always the same.
I noticed, however, that when the output is turned off (or if you set the output voltage to 0V.) Offset output terminals is 0.550mV ~. Someone can do this check, please?
Thanks.
cidak:
Thanks to the attached chart.
This measure seems to bring error very rarely.
In my case, the error is fixed over the entire range in output from 0 to 42 volts (my model is a DP811A).
Via software or hardware, How can you adjust this? You think?
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