Products > Test Equipment
Rigol DP832 - Firmware list and bugs
skander36:
Mine , at 0V on channel 2 show (on DMM) -68mV and only to 39mV set show 0 on DMM - this for automated calibration (Matlab or Pyton same result)
But if I do a manual DAC calibration on CH2 I can obtain 1 to1.5 mV for Zero set. So PSU can do.
So from were the negative offset using calibration constants ... ?
JDubU:
--- Quote from: skander36 on March 16, 2020, 11:00:54 pm ---Mine , at 0V on channel 2 show (on DMM) -68mV and only to 39mV set show 0 on DMM - this for automated calibration (Matlab or Pyton same result)
But if I do a manual DAC calibration on CH2 I can obtain 1 to1.5 mV for Zero set. So PSU can do.
So from were the negative offset using calibration constants ... ?
--- End quote ---
Don't know, but it could be that there is just too much negative offset in the channel's voltage control loop for the limited number of calibration coefficients to compensate at millivolt resolution. I'm surprised that they don't have a DAC calibration point at zero volts.
garrettm:
--- Quote from: Gandalf_Sr on March 16, 2020, 10:06:44 pm ---garrettm
Don't feel bad, we know you were sincere in your effort to help. I can test your modified code if you like as long as it's adapted to:
a. NOT clear the DP832A cal and
b. NOT write the new Cal to the DP832
It should be pretty straightforward to come up with some test code that sets up the DP832 to output a certain voltage and then read the value from the 34461A
Thanks for your help.
--- End quote ---
Thanks. I've already written the new test class (TelnetTest.java). It starts with getting readback from the DMM in dc voltage and current first, then steps through reading back the PSU cal points. Only ch1 is tested since the others are identical. Nothing is cleared and nothing is saved. However, a power reset is needed after the test to resume normal operation of the PSU.
All that needs to be done is to modify the SCPI strings so that a particular DMM can achieve proper configuration and readback. After that, calibration should be a breeze. Just need to copy the modified commands from TelnetTest into TelnetCal.
Again, since I've written these scripts I think they are simple, but obviously thats not true for everyone. Especially if you don't know Java. But if you do know C or C++ its very similar, just with OOP concepts where they make sense, like the Telnet clients. Of course there are the Java bultin objects and methods, like for Strings and Scanner. But those you can look up in Oracle's online documentation.
Finally, I've updated the documentation to reflect the recent changes and provided .txt of the output of both TelnetCal and TelnetTest so people can see what its supposed to do when working correctly.
If there are any issues let me know and I'll try and sort them out ASAP. I think using Telnet is honestly the easiest option when calibrating, but if I'm the only one who can get this working, then I'll probably just take it down. No need to "help" people break things that are already working.
garrettm:
--- Quote from: skander36 on March 16, 2020, 10:30:46 pm ---I know about them but I want to know how they was obtained.
Can you check on your PSU if on CH2 range 0-40mV is ok ?
Thank you very much !
--- End quote ---
I just checked my DP832A and entering 1mv gives 0.7mv on my DMM, 0.000V on the display and entering 10mv gives me 9.4mV on my DMM and 8mV on the display. So TooOldForThis's cal points seem right.
The cal point values are visible in the manual calibration mode, though you would need to look at an instrument that HASN'T been calibrated using one of the scripts to see what the factory cal points are. I am of the understanding that you can actually add cal points and make them arbitrary too. I just haven't played around with that yet.
The reason I say this is that when my calibration was broken through the firmware update and cleared after a failed auto calibration, all the cal points were blank and showed up to 52 steps! So it would seem that custom cal points and increased number of cal points might be possible. But maybe not. It really depends on how Rigol implemented the linearization algorithm.
skander36:
--- Quote from: garrettm on March 17, 2020, 12:58:11 am ---
The reason I say this is that when my calibration was broken through the firmware update and cleared after a failed auto calibration, all the cal points were blank and showed up to 52 steps! So it would seem that custom cal points and increased number of cal points might be possible. But maybe not. It really depends on how Rigol implemented the linearization algorithm.
--- End quote ---
Yes , that I have seen on my PSU also . There were 52 points of calibration . And the first time when I try maual calibration was 44 .
About calibration point I see that is the only one set that is used for both DAC channels (CH1 and 2) .
So , as long as calibration is done well on CH1 but not on CH2, and manual calibration on CH2 adjust them, I see a hardware problem rather than a calibration values. I need to mention that over 100mV , CH2 is very precise .The problem is only to 0-40mV and slowly increase precision to 100mV.
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