Agilent 33120A: wrong Sine Waveform Amplitude

[vix]

I have an Agilent 33120A function generator, and I control it with LabVIEW 8.2.1 and CVI 6.0 via GPIB and RS232 interfaces.

I've been using the driver downloaded from NI site but I found a strange problem.

Here the steps to reproduce it (I hope):

1. power-down the 33120A, then power it up
2. control the instrument with CVI, and generate for example a sine wave with 300 mVPP amplitude (hp33120a_ConfigureStandardWaveform function with Amplitude input to 0.3)
3. close CVI communication with instrument
4. set waveform amplitude to mVRMS with the 33120A fron panel buttons
5. re-open CVI communication
6. control the instrument with CVI again, and try to generate a sine wave with 300 mVPP amplitude again (hp33120a_ConfigureStandardWaveform function with Amplitude input to 0.3). A 300 mVRMS sine wave is generated.

After some tests, I found out that you have to set waveform amplitude to mVPP with the 33120A fron panel buttons before controlling it with CVI; otherwise the mVRMS setting is not changed by CVI driver. Or you must power-down then  power-up the function generator, andthis setting isresetted to mVPP (instrument default?)

If you use LabVIEW everything works fine.

If you use a 33220A function generator with the same driver everything works fine.

Is this an expected behaviour, or is this a driver bug?

[DaBenny]

Hello vix,

Thanks for the detailed notes, the behavior that you are seeing could be a result of the firmware on your 33120a, have you tried updating to the latest?

[DaBenny]

Have you got any update?

[vix]

Sorry for the late answer, but for a strange reason my question has been posted into two different threads, and some additional informations are available in the other thread

I suggest you to stay tuned on this one.

Sorry again for the inconvenience