Reading a DC Voltage from CH1

[Ostin Flores]

Hi,

I am working on a simple application to send and read a DC voltage from The Digilent Discovery 2. I am doing this through a python scrip and my FDwfAnalogOutNodeOffsetSet command works fine but when I feed this output voltage into CH1 Scope I get a small voltage reading (~1mV) regardless of what I send. Below is the code that I am using...

    #Code to open devise....

    HeaterVoltage = c_double()
    dwf.FDwfAnalogOutNodeOffsetSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(0.3)) #Sending 0.3V out
    time.sleep(2)
    dwf.FDwfAnalogInChannelOffsetGet(hdwf, c_int(0), byref(HeaterVoltage)) #Reading the Voltage back
    print("Voltage readback: " + str(HeaterVoltage.value))

I am using the Discovery BNC CH1 is my output 0 ohm termination, input is CH1 and I tried both AC and DC coupling. Can you please tell me if I am doing something wrong?

[attila]

Hi @Ostin Flores

The FDwfAnalogInChannelOffset refers to the oscilloscope vertical offset. Use FDwfAnalogInStatusSample for to get a single ADC sample.

See WF SDK/ samples/ py/ AnalogIn_Sample.py

See in WF SDK/ manual.pdf FDwfAnalogInStatus FDwfAnalogInStatusSample 

dwf.FDwfAnalogOutNodeOffsetSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(0.3)) #Sending 0.3V out
time.sleep(2)
dwf.FDwfAnalogInStatus(hdwf, c_int(0), None)
dwf.FDwfAnalogInStatusSample(hdwf, c_int(0), byref(HeaterVoltage)) # Ch1
print("Voltage readback: " + str(HeaterVoltage.value))

 

 

[Ostin Flores]

On 2/22/2022 at 8:38 AM, attila said:

Hi @Ostin Flores

The FDwfAnalogInChannelOffset refers to the oscilloscope vertical offset. Use FDwfAnalogInStatusSample for to get a single ADC sample.

See WF SDK/ samples/ py/ AnalogIn_Sample.py

See in WF SDK/ manual.pdf FDwfAnalogInStatus FDwfAnalogInStatusSample 

dwf.FDwfAnalogOutNodeOffsetSet(hdwf, c_int(0), AnalogOutNodeCarrier, c_double(0.3)) #Sending 0.3V out
time.sleep(2)
dwf.FDwfAnalogInStatus(hdwf, c_int(0), None)
dwf.FDwfAnalogInStatusSample(hdwf, c_int(0), byref(HeaterVoltage)) # Ch1
print("Voltage readback: " + str(HeaterVoltage.value))

 

 

Great!!! This worked beautifully!!

Thanks for the help :)