I’m trying to understand the evaluation board by starting with a simple voltage measurement with the supplied Labview project. Until now I couldn’t get this working properly when running the Labview executable and using the ‘RMS voltage’ VI. I would expect that the registers AVRMS,BVRMS,CVRMS contain a value representing the voltage after certain settings are applied (described below). Where
a value of 3766572 corresponds to the full scale output of a sinusoidal with 0.5V amplitude. Instead I see values fluctuating between 2 and 40k randomly, almost identical for the 3 phases (when different voltages applied). Also from the Quick startup VI, I can’t get any meaningful voltage information as well.
I’ve connected an single phase AC voltage line to input A, floating voltage input B and shorted voltage input C. There are no CT’s connected. I use the registers settings AVGAIN, BVGAIN, CVGAIN = 0x400000, CFxDEN=0d1000; VLEVEL= Ufs/Un*4e6= 500/230*4e6= 8995652, VNOM = U/Ufs*3766572= 230/500*3766572=1732623, xVRMSOS=0, GAIN=0x0000. I also tried to connect DVDD to VN pin and to use a separate power supply to connector P10.
Any idea’s what might go wrong here? I’m hoping that someone has an idea .