I tested today how fast is remote control using SCPI commands via serial (USB port). It's initiate by question got by email from guy who would like to know is it possible to generate square wave signal faster then 10 Hz. He has another brand power supply that cannot offer more then 5 Hz.

Without any optimization and with selecting most demanding viewing mode (bar graphs) that we are refreshing as soon as any change is detected (but not faster then ~300 samples/s) I got the following:

Display is ON (that means display will be frequently refreshed):

• 18 Hz, if connected load does not cause changing of mode operation (or CV only)
• 12 to 14 Hz depending of the selected viewing mode, and when mode operation is changing (CV-CC)

Display is OFF (option DISPLAY_OPTION=0 in conf.h file):

• 36 Hz regardless if the mode of operation is changing or not!

Here is a screenshot for 12 Hz SCPI VOLT 0.1 - VOLT 5.1 changed in the loop on the both channel (PSU is in the TRACking mode of operation):
In firmware M4 we are planned to add SCPI LIST subsystem when you'll be able to load waveform shape that will be internally executed in the loop. Our goal is to reach 120 Hz (sine wave generation) in that way, but we'll see.

Apart to digital (SCPI) remote programming it's already possible to achieve much higher speed using so-called remote voltage programming (VOLT:PROG). In this case the PSU can easily survive much faster changes, e.g. 500 Hz as shown in next couple of screenshots (square and sine, yellow trace is output, cyan is controlling analog signal produced by signal generator):