EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: petemate on August 12, 2020, 05:04:55 pm
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Hi, I have a Voltech PM300. During normal front panel operation, the display updates approx once a second. As I understand it from the terrible manual, the display averages a number of readings and updates the display. Makes sense to limit that display update rate, as it is impossible to read an LCD that is updating too fast. But I would like to run at "higer speeds" when I remote control the device. The device apparently samples at 200kHz(there has been some discussion on this in other posts, has something do with the ADCs being only clocked at 50kHz), so it would be nice to be able to measure e.g. 10 or 100 times a second, so that I can quickly obtain data in a sweep and not have to wait 1 second at every time step. However, I can't figure out how to do this, if at all possible.
Using the :FRD? command to read data using RS232, I am able to read data at the same speed as the display updates, since this command is synced to the "New data available" status bit. There is a "set averaging" command(:AVG) where you can set a "depth" from 1 to 16 or set it to auto. This just doesn't do anything. I dont know if this is related to the "long averaging" function, which is only available on the PM100. Does anyone know what this do and what the depth actually sets? If I set averaging to "auto", returned values are all zero.
Later on in the RS232 interface description, there is an appendix with "configuration commands". An interesting "parameter" called "number of samples"(:CFG 8) might be of interest. However, this seems reads back to 400 no matter what I do. Also, 400 samples at 50kHz is 8 milliseconds, so that should already be enough. There is no information regarding what this number of samples sets and if it actually does anything. That goes for the majority of parameters listed in this section("Jitter generator" and "sample pre-filter" is mentioned nowhere else).
I'd be happy to hear what experience you have with the PM300 and/or PM100. Some options are only available on the PM100 and vise versa. I think that it could be the case for the "number of samples" command, but then it should be listed.
Here is a link to the manual for the unit as well as the RS232 interface: https://www.voltech.com/Support/Forum/tabid/151/forumid/6/scope/threads/Default.aspx (https://www.voltech.com/Support/Forum/tabid/151/forumid/6/scope/threads/Default.aspx)
Edit: Forgot the other question that I wanted to ask: Is it possible to disable display blanking remotely?