Siglent SDG5082 PP Output Quirk - Page 1
Forum section: electronics / testgear

author: daveyk
author_rank: Frequent Contributor
timestamp: June 19, 2020, 08:27:15 pm
content: For the most part, I am happy with my Siglent SDG5082. I just ran in to a weird quirk again today, the same one I had problems with once before right after getting it.I use it with automatic test software that I wrote. The first time I experience this quirk, which I will shortly explain, I blamed it on bad code that was sending wrong commands to the generator. Today, I am using the same program I used with it many many times in the last two months.My test program could not get working correctly, it would stall trying to set the PP output, while monitoring with the scope. So here's what happened: The generator was set to 4.5MHz Sinewave, 10V P-P, 50 ohms. With zero external attenuation the scope saw about 6.8v P-P, not anything close to 10v P-P.After messing around, I powered down the generator and powered it back up. 10V P-P on its display and its output was 10.xxx volts P-P. Then everything was fine and the program worked as it should after that.It's as if sometimes, the power supply feeding the output buffer doesn't aways come up to the correct voltage. Powering down and the back up fixes it. In the case today, I turned on the generator and waited about 30 minutes to start an instrument calibration and experienced the issue. So it was probably like that when I first turned it on.If it is a problem with the generator, and I contact Siglent and I tell them I've only seen the issue twice, about a month apart, how the hell could they fix that, unless it is a known quirk with the SDG5082?I do like this gen, but kind of wish I spend about $300 more and got the SDG6000 series.

author: daveyk
author_rank: Frequent Contributor
timestamp: June 19, 2020, 09:37:00 pm
content: Okay; just experienced the quirk again. This time, the P-P was locked. I couldn't change it with the front panel. Oh, I could change the numbers on the Amplitude Output, but the output voltage did not change. I had to power it down and then back up to get it to work. So maybe the issue is not a power supply start-up issue, but the output control fails.It may have a problem; damn it.

author: tv84
author_rank: Super Contributor
timestamp: June 19, 2020, 09:51:41 pm
content: Flash the latest FW again.

author: daveyk
author_rank: Frequent Contributor
timestamp: June 19, 2020, 10:02:18 pm
content: I'll download it and do that; thanks for the suggestion.I'm ready to take it out of service and pulling my hair out.

author: daveyk
author_rank: Frequent Contributor
timestamp: June 19, 2020, 11:44:21 pm
content: Okay, I re-flashed the firmware.I also found where my voltage setting routine was passing a double-precision variable as the set voltage. I have no idea why I used double precision; it's been too many years.I changed the routine to format the wanted voltages (please note, I have not changed the routine for the SDG5082; this was originally written for the SDG2042X; SDG5082 is code compatible):'===================================================================================Public Function fnctSDG_SetVoltage(Volts As Double)Dim IDN As VariantDim Status As Variant'' AddressIf SDG2000xAdr <> "" Then'SDG2000x.WriteString "C" & Trim(Str(SDG2000xChannel)) & ":BSWV AMP," + Format(Str(Volts), "0.000")Sleep (250)Status = fnctSDG_GetVoltage'End If'Exit Function'End Function'===================================================================================In one case the program was trying to set the voltage to: 6.85300016403198 voltsNow it just sets it to: 6.853 volts.I have no idea if that is a problem for this SDG5082, or not. It never caused an issue with the SDG2042X.I will see if it craps out again.Dave