A quick question: I don't seem to find the command one might use via pyremote to set the gxsm feedback on or off (equivalent to the toggle 'Enable feedback controller' in Advanced->Z Control of the DSP control window.
Is this available?
Thank you,
Nick
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Correct. Please use CP=CI=0 or small to slow or freeze Z.
Also (advanced) consider using the "CZ-FUZZY-LOG" Transfer mode (for the mixer channel used) together with "Level" setting:
Use "Level=0" for normal operation/with Z feedback (exactly =LOG mode). But once Level is set > max current possible Z will be forced to the value set in Z-Pos/Setpoint.
If Level is set to say 0.1nA Z will got the Z-Pos if this max or compliance current is NOT exceeded. (Safety mode)
HOWEVER, a warning here: With usual feedback settings for CP/CI you may create a instability in Z around the tunnel position as this mode attempts to transition between Const-Z (CZ) and (LOG) mode (FUZZY).
To make this gentle, I advise to lower CI=CP by at least 10x from normal.
Example CP=0, CI=4
Then you can manually and safely fine adjust Z while scanning!
The Z-Set-Point is internally limited to about +/-100A as intended for HR-AFM.
Thus get your "Z" offset right so Z-Scan is operating around 0.
PS: My Shift-F4/F3 action scripts are doing this in the proper order automatically.
Intend for this FEEDBACK switch is:
The feedback on/off is a more drastic measure and usually there is no need to "disable" it this way. The intend for this switch is mainly for user controlled "start up" after DSP power up to enable the Z axis from been set to 0V at DSP power up (and kept until enabled) manually. -- See it as a electrical safety measure!
Alright, thanks for the follow-up! I was looking at the code as well, but I didn't propose any changes to expose it. I'll avoid considering it for now.
Thanks,
Nick
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi,
A quick question: I don't seem to find the command one might use via pyremote to set the gxsm feedback on or off (equivalent to the toggle 'Enable feedback controller' in Advanced->Z Control of the DSP control window.
Is this available?
Thank you,
Nick
I have in mind that there is not command for that but you can set the feedback parameters ci and cp to 0.
Thorsten :-)
Correct. Please use CP=CI=0 or small to slow or freeze Z.
Also (advanced) consider using the "CZ-FUZZY-LOG" Transfer mode (for the mixer channel used) together with "Level" setting:
Use "Level=0" for normal operation/with Z feedback (exactly =LOG mode). But once Level is set > max current possible Z will be forced to the value set in Z-Pos/Setpoint.
If Level is set to say 0.1nA Z will got the Z-Pos if this max or compliance current is NOT exceeded. (Safety mode)
HOWEVER, a warning here: With usual feedback settings for CP/CI you may create a instability in Z around the tunnel position as this mode attempts to transition between Const-Z (CZ) and (LOG) mode (FUZZY).
To make this gentle, I advise to lower CI=CP by at least 10x from normal.
Example CP=0, CI=4
Then you can manually and safely fine adjust Z while scanning!
The Z-Set-Point is internally limited to about +/-100A as intended for HR-AFM.
Thus get your "Z" offset right so Z-Scan is operating around 0.
PS: My Shift-F4/F3 action scripts are doing this in the proper order automatically.
Intend for this FEEDBACK switch is:
The feedback on/off is a more drastic measure and usually there is no need to "disable" it this way. The intend for this switch is mainly for user controlled "start up" after DSP power up to enable the Z axis from been set to 0V at DSP power up (and kept until enabled) manually. -- See it as a electrical safety measure!
-P
Last edit: Percy Zahl 2023-12-11
Hi Thorsten,
Alright, thanks for the follow-up! I was looking at the code as well, but I didn't propose any changes to expose it. I'll avoid considering it for now.
Thanks,
Nick