[TriEmbed] Rigol and Siglent warnings (rants)

[Pete Soper]

If you're intending to rely on remote control/logging with Rigol and/or 
Siglent test equipment via ethernet and USB, know that both are flakey 
to the point of rating a perfect zero stars label of "Genuine Piece of 
Crap"*. I'm talking about the I/O interfaces, not the basic functioning 
of the equpment. My DM3068 DMM and SPD3303S power supply both perform 
fantastically when you are just looking at the displays (but while I'm 
at it: be VERY CAREFUL with the voltage/current limit control knob on 
the Siglent 3303 series supplies, as they have random, viciously 
variable acceleration behavior and you'll blow up your equipment if you 
forget to turn the output off while making an adjustment. e.g."2.9 
volts, 3.0 volts, 3.1 volts, 6.4 volts. Oops!").

Also, as an FYI, Tequipment has dropped Siglent. The URLs via the 
outside are still valid, but if you go to their site you'll find no 
trace of this line.

Finally, to get all the rants out of the way, know that Rigol's service 
organization in the US is modest with a four point type, lower case "m". 
But I did get an official dispensation to break the warranty seal and 
replace a fuse in my DMM and I thank my lucky stars I didn't have to 
ship it to them.

I have workarounds for getting control/logging to work with Rigol via 
vxi11 and with Siglent via /dev/USBTMC* that only took several dozen 
hours of futzing to work out. For vxi11 you MUST set the instrument 
object lock_timeout field to zero, and for USBTMC operations where you 
are also plagued by error 110 (which just manifests as OSError in 
Python), the fix is to resend the last query as the Siglent has 
worthless crap in its USB interface that doesn't seem to understand the 
concept of asynchronous I/O and it drops queries on the floor randomly, 
just like Siglent. Maybe one stole the other's super quality firmware?  
I could go on to discuss the sterling quality of the sigrok-cli user 
interface documentation and command line semantic handling, but I'll 
save that for some other day, and besides I want to contribute drivers 
to those guys and not get them PO'd from the get go.

-Pete.

*For more info on the "Genuine Piece of Crap" label, hear what Neil 
Young has to say <https://www.youtube.com/watch?v=s_r9AnvHLjk> about the 
subject.


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