Products > Test Equipment

Chinese Electronic Load 500W module Sousim 500W

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kawal:
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.





samofab:
I have similar unit. I plan to control it using ESP32, but I didn't come around to it yet. Works nicely using the dongle, though.
I'm attaching a python script if you're interested.. (on second thought, I'm not sure if this is the correct one, but I'll leave it here until proven otherwise)

kawal:
Script seems to have errors . But thanks anyway.

kawal:
Tried connecting to the TX and RX port available on the board.
Looks like I am able to get MODBUS RTU data



kawal:
Well tested the unit from 1.5V to 31V  and up to 5A  load
the read back was fairly accurate with a slight offset on the current readings of about 10mA .
 I was testing the different  data  groups on Modbus. 

The unit  uses
Holding Registers for settings
HR2 Enable/ Disable
HR3 Overvoltage (20000 default =200.00V)
HR4 Amp setting in  mA
HR9 Over current setting (5500= 55A)

Input registers  for readouts
IR6 Voltage Readout
IR7 Current readout
IR8 Power readout
IR9 Resistance setting readout

The fan was not spinning until the unit got hot 45..50C   and the speed did change with temperature. So there is some kind of fan control


I lost communication while trying to change register HR5 and was unable to get it back. Hope  it comes back to life.

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