I decided to take a risk and get one of these RS485 controlled electric loads. Haven't tested so far - waiting for a rs485 dongle .
Spec are supposed to be 500W , 200V , 60A ,CV, CC, CW and CR modes.
While build quality seems OK there is a slight problem that the system uses recycled power Fets . Fets seem original IRFP264 devices rated @ 250V .
(legs are covered with shiny solder to a point , looks crusty close to case ).
The design is very simple - basically a STM32 used to control 8 transistors via op amps.
Read back of voltage and current is done by STM as well. The built in ADC/DAC are 12 bit so appropriate for such design from the 80c .
There is 1 thermal sensors (transistor used as diod ) and room for 2 more sensors that would connect in parallel to the one populated.
Fan is controlled from the ULN2003 - most likely PWN controlled.