Analog input signal keeps increasing

[Khassan]

Hello,

I am new to NI-DAQ. I run a sample code provided by NI in Visual C++ from "\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Analog In\Measure Voltage\Cont Acq-Int Clk".

I am supplying 10HZ sinusoid from function generator, it gets the signal, but it starts to increase signal, i.e. acquired sinusoid moves slowly from -2.5V : 2.5V to 5V-10V. 

Regards,

KY

[Henrik_Volkers]

Seems that you source (generator) is really floating 😉

Since the DAQ input outputs a tiny current (input bias current) you need to provide a current path to A(in)GND. Have a look at the DAQ input connections diagrams in the DAQmx manual.

Usually a resistor (100k?) from Ai- to AGND will provide a bias current path and fix the signal  (and your problem).

[Khassan]

Thank you very much, I have already tired it before, but my problem was that the input terminal configuration for the AI channel was set to default (DAQmx_Val_Cfg_Default)
and by default it uses Differential mode (DAQmx_Val_Diff), whereas Referenced single-ended mode(DAQmx_Val_RSE) was required.

Hope it will help others...

Regards,

Khassan from Kazakhstan