Cannot set amplitude on channel 0

[einsmein]

I was trying to set an amplitude on the MFLI, which I assume would be mfli1.sigouts[0].amplitudes[0].value(). I got an error that there is no attribute value. When I checked the snapshot, there is no parameters on 0th channel.

> mfli1.sigouts[0].amplitudes[0].snapshot()
{'functions': {},
 'submodules': {},
 'parameters': {},
 '__class__': 'zhinst.qcodes.qcodes_adaptions.ZINode',
 'name': 'mfli1_sigouts0_amplitudes0'}

However, I could set the amplitude with mfli1.sigouts[0].amplitudes[1].value(0.05)

> mfli1.sigouts[0].amplitudes[0].snapshot()

Is it intentional that it's not zero-based index?

[tobiasah]

@einsmein Thanks for reaching out to us. This looks weird ... it should be zero-based indexed by all means 😇

However, I could not reproduce it on my machine. I can both read and write to the ampilitudes[0].value node.

The snapshot returns the follwoing:

{
    "functions": {},
    "submodules": {},
    "parameters": {
        "value": {
            "__class__": "zhinst.qcodes.qcodes_adaptions.ZIParameter",
            "full_name": "zi_baseinstrument_devxxxx_sigouts0_amplitudes0_value",
            "value": 0.100006103515625,
            "raw_value": 0.100006103515625,
            "ts": "2022-10-14 12:14:01",
            "unit": "V",
            "name": "value",
            "label": "value",
            "post_delay": 0,
            "instrument": "zhinst.qcodes.qcodes_adaptions.ZINode",
            "instrument_name": "zi_baseinstrument_devxxxx_sigouts0_amplitudes0",
            "inter_delay": 0
        }
    },
    "__class__": "zhinst.qcodes.qcodes_adaptions.ZINode",
    "name": "zi_baseinstrument_devxxx_sigouts0_amplitudes0"
}

May I ask for the following information:

• qcodes version.
• zhinst-qcodes version.
• zhinst-toolkitversion.
• zhinst-core version (if you are using LabOne < 22.08 the version of zhinst instead)
• LabOne version
• Firmware revision

Just so that I can try to reproduce it.

[mehdialem]

@einsmein and @tobiasah, Thank you for the discussion. Let me clarify that both of you have correct observation but the difference is in the installed options on your instruments. @einsmein's device does not include the MF-MD option while @tobiasah's device has it. The screenshots below shows the differences in the UI:

Device w/o MF-MD option

Device w/ MF-MD option

As evident from the screenshots, MFLI with MD option has 4 signal amplitudes indexed as 0, 1, 2, and 3. However, the device without MD option has only 1 signal amplitude which is the index 1 out of those 4 amplitudes. The reason is to decouple the phase of reference for demodulator (index 0) from the phase of signal output (index 1).

So in summary, the user of MFLI without MF-MD option has only one choice for output amplitude and it is index 1

[einsmein]

@tobiasah @mehdialem Thanks for the quick reply, and for the explanation. I still don't understand why the output signal params have to be at index 1 instead of 0, but I assume that comes from some lower-level implementation.

[mehdialem]

@einsmein, Let me explain it further using the screenshot below. One would like to have independent phases for signal generation (red-box phase in the screenshot with index 1) and for signal demodulation (green-box phase in the screenshot with index 0). Now suppose that the amplitude has an index of 0 in your script and you upgrade your MFLI with the MF-MD option. In this case your old script results in a different behavior for the new situation because it uses index 0 which means the signal output has the same phase of demodulator (green box). So this kind of indexing avoids behavioral incompatibility between instruments with and without options. I hope it answers your question.