Agilent 33120A: wrong Sine Waveform Amplitude

[DaBenny]

R&D send the FGEN to mVRMS by hitting the following button combination Ampl >> Enter Number >> v (m Vrms)

This sets the display to m Vrms when I ran the VI it resets it to mVPP.

[vix]

---

DaBenny wrote:

R&D send the FGEN to mVRMS by hitting the following button combination Ampl >> Enter Number >> v (m Vrms)

This sets the display to m Vrms

---

OK, that's right

---

when I ran the VI it resets it to mVPP.

---

 When I run a LabVIEW VI everything works fine (see my first post) because LabVIEW driver sets the property VOLT:UNIT VRMS (see one of my previous posts).

 When I run the CVI code you posted above this property isn't changed because CVI driver doesn't set the property VOLT:UNIT (see one of my previous posts).

[DaBenny]

hi vix,

the Agilent support response:

unfortunately, the 33120A was obsoleted in 2005 and is now past its repair support life. The firmware in the 33120A was not updatable through the remote interface like our newer products are, so any kind of upgrade at this point would not be possible. Way back when your unit was manufactured (~1994), the 33120A’s did not have a dc mode. Maybe that’s what you’re missing. At any rate, we can’t update it anymore. Sorry. Regards,

Ron Knight
Inside Applications Engineer
Agilent Technologies, Inc.
Americas Technical Contact Center
Online Technical Services
800-829-4444, enter Case ID# 2297230523

I let you know any update

[DaBenny]

Hi vix,

R&D was unable to get the 33120A to stay in a mVrms state after running the CVI program referenced previously. They did the same steps you mentioned : 

1) Cycle power to the instrument

2) Run the CVI program that I posted to set the device to 300mVPP

3) Set the instrument to mVrms by pressing Amplitude->Enter Number->mVrms

4) Run the CVI program again. This step caused the instrument to be set back to 300 mVPP, NOT mVrms.

So, this tells me there is either an issue with the firmware of the customer's device (which we cannot fix), or there's an issue with the instrument driver you are using.  I think it's probably the latter, since you said that the LabVIEW drivers seem to work. You may want to re-download the driver. I downloaded the LabWindows/CVI IVI driver from here