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Author Topic: 33120A Function Generator Adjustment Via GPIB  (Read 1401 times)

Offline mf1753

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33120A Function Generator Adjustment Via GPIB
« on: 07-17-2019 -- 19:03:08 »
Howdy all, first post...

Has anyone had an issue with adjusting a 33120A via GPIB?  I've completed the following steps:

1) Unlock generator CAL:SEC:STAT OFF, <code>
2) Set # of setup CAL:SET <setup number from manual>
3) Set readback value from standard CAL: VAL <value>

(I repeat 2 & 3 for sections, essentially the Function Gain and linearity adjust that is 2-7)

4) Lock instrument CAL:SEC:STAT OFF, <code>

When I reverify, the values are not saved.  Am I missing an enter, or 'commit' type statement?  I'm able to do this manually but mysteriously I can't find any METCAL examples.  I've gotten this to work many aeons ago (<15 yrs) but for the life of me can't remember what command I'm missing for these values to take.


Offline silv3rstr3

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Re: 33120A Function Generator Adjustment Via GPIB
« Reply #1 on: 07-18-2019 -- 14:28:36 »
That's funny, a similar thing happened to me earlier this week.  I was adjusting flatness manually and hit an arrow key on the last step instead of enter and it displayed "not stored" or something similar.  Had to do it all over again as it always seems to be the last test at times.  Check out the note on page 68 & 70 in service manual, it may apply.   

You will press ENTER twice for each calibration step, once to select setup and once to enter the adjustment values.

The function generator stores twenty two constants related to 1MΩ and sixteen for 50Ω.  The constants are stored after completion of setup 22 (High Z Output) and can be aborted after that step.  No constants stored if procedure is aborted at any other setup.

I've always automated the performance verification and manually did the alignments as needed.  You may need to go line by line utilizing Step (F11) in Editor or send each SCPI command manually through NI Max to see where it's actually canceling out of the alignment.   
« Last Edit: 07-18-2019 -- 14:32:00 by silv3rstr3 »
“They are in front of us, behind us, and we are flanked on both sides by an enemy that out numbers us 29:1. They can’t get away from us now!!”
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Offline mf1753

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Re: 33120A Function Generator Adjustment Via GPIB
« Reply #2 on: 07-18-2019 -- 20:51:57 »
Good idea, actually had MAX open when I started debugging it.

I thought maybe when I stepped to cal setup 08 that would tell the generator those values were committed.

I essentially verified the Function Gain, then saved the readback values from a DMM to variable, unlocked the instrument, set and wrote each of the cal setup values back, locked, then read each back and the values weren't updated.  I could tell that I wasn't successful because the cal count didn't update as well.

The manual method in these pages absolutely worked which is promising..

Some instruments will allow button depression type mapping via GPIB but technically there would nothing to depress since the menu isn't actually on.

Offline Hawaii596

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Re: 33120A Function Generator Adjustment Via GPIB
« Reply #3 on: 07-23-2019 -- 21:32:55 »
Off the cuff thought... I've seen on some of these where there are different available adjustment steps depending on what firmware rev is installed. Not sure if this applies here.
"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind."
Lord Kelvin (1824-1907)
from lecture to the Institute of Civil Engineers, 3 May 1883

Offline mf1753

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Re: 33120A Function Generator Adjustment Via GPIB
« Reply #4 on: 07-24-2019 -- 14:29:46 »
Hey Hawaii596...I've seen those cal points added to the firmware revisions, might be helpful (if the generators live through the update).  I called Keysight and they didn't really want to talk about these since they EOL'd in 08'.  I know most likely still owns or supports them.


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