Hi Siglent,
Would it be possible to increase the display update rate of the SDM3055, or give users the option to do it? Currently, there isn't much difference in "slow", "middle", or "fast". The data sheet states that the options sample at 5, 50, or 150 times per second. This is useful if logging and viewing the file after. Also, since middle and fast drop a digit of resolution, they seem to auto range and display a new value faster. But, the display update rate doesn't seem to change much, if at all. So while the log of values might allow you to see fast changing values, you can't see them in real time. The display, even on fast mode, seems to update 1 time per second, even though it has captured 150 values. I think it should be possible to update the display at 10 times per second for example, and average 15 captured readings into 1. Therefore, you get 1 average of 15 readings every 100ms on the display, and 150 captures averaged into 10 readings every second.
I have attached a csv (unzip with 7z or alternative, windows doesn't work for some reason) file showing the power of 150 samples/s. I programmed my DP832 to sweep from 0v to 2v in 2000 steps. The DP832 seems to be able to change 100 steps (100millivolts) in 1 second, so the meter sometimes captures the same value twice since it samples at 150/s. Why waste the speed of the ADC by limiting the display update? If you want a more stable reading, then you will use the "slow" mode by default anyway since it gives you the full 5 and 1/2 digits. You can also do something creative with the "middle" option, like give it 5 screen updates per second. Currently it's kind of useless, since it's slower than the "fast" option, but still loses a digit of resolution.
Regarding the problem that the meter doesn't save the UI settings on reboot, I looked into the xml file that you can create to save settings. Even when setting the meter to boot to "last", the xml file still shows "factory default" in the power up field. Maybe the power on "last" feature does work correctly, but the meter just doesn't set the parameter correctly. I tried editing the xml file by putting "last" in the field and recalling it in the meter but it didn't do anything. I also can't copy the edited file to the internal storage since the built in file manager doesn't allow it. I also tried recalling the edited file, and creating a new one in internal storage with the settings, but that didn't solve the issue either.