rf-lloop:
To be honest is hard to believe it is a hardware issue - this is an arbitrary type generator.
Anyway, thanks for your assistance ...
M
It is arbitrary generator, yes.
But I know how Square function signal is produced in SDG1000 series.
All units what I have tested with all firmwares this Duty % adjustment have worked and also works with unit what I have in my own demo use.
Square wave works internally so that it still produce Sine wave! But in this function internal Sinewave do not go to output amplifiers. It go to PECL comparator. Other input of comparator get this Sine and other input get adjustable DC for duty adjust. When DC is middle of sinewave p-p it produce 50% Duty square out and this signal go to output stages.
Pulse function, what also produce rectangle, can also produce 50% duty rectangle signal what is square wave.
Using Pulse function signal is produced totally different way directly by DAC. In many cases (and up to Pulse mode freq top limit, it is perhaps best mode for produce square wave and if want, set it for Duty %, so changing frequency do not affect duty.
Both methods have some advantages and disadvantages.
If Square function produce without any problem always 50% duty square independent of Duty setting it tell least to me that PECL do not work right or PECL do not get adjustable treshold voltage and problem is there and of course failure can be many kind of, some component, some PCB issue etc.... rare but possible.
I have experience with these equipments and have also warranty time repair service and I have also repaired these units in some rare cases. (example in old case when Siglent factory have accidentally installed wrong type of CH2 output ampliviers.) Also I have investigated quite deeply this Square function circuits due to fact that old times there was this "famous" glitch" issue what also was extremely pure hardware issue due to wrong setting of PECL comparator hysteresis setting (+ some cases also internal sinewave noise.) (both of these have been long time ago solved By Siglent)
Of course also FW may do same thing if there is problem with DAC driving what produce adjustable DC to PECL for square duty setting. But as told, I have not yet seen any FW version with this bug. So, if this do not work, my susppect is HW failure.