I'm using PXI-4461 based on Visual Basic programming. My goal is to generate
differential mode signal with 0.5v offset using the PXI-4461 and VB.
The followings are details, but I'm attaching a ppt file for better understanding of my question.
How can I shift up the negative sinewave by +1v?
The following is the VB code which is the same as the code in the attached ppt file.
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Public Sub test(ByVal numSamples As Long, ByRef writeData() As Double, dataRate As Double)
If chanDAQ.taskHandle <> 0 Then
DAQmxErrChkMod DAQmxTaskControl(chanDAQ.taskHandle, DAQmx_Val_Task_Unreserve)
DAQmxErrChkMod DAQmxStopTask(chanDAQ.taskHandle)
DAQmxErrChkMod DAQmxCfgSampClkTiming(chanDAQ.taskHandle, "", dataRate, DAQmx_Val_Rising, DAQmx_Val_AcquisitionType_ContSamps, numSamples)
DAQmxErrChkMod DAQmxWriteAnalogF64(chanDAQ.taskHandle, numSamples, False, 10#, DAQmx_Val_GroupByChannel, writeData(0), sampsPerChanWritten, ByVal 0&)
DAQmxErrChkMod DAQmxStartTask(chanDAQ.taskHandle)
chanDAQ.taskStarted = True
End If
End Sub
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<Description to explain the same problem descripbed in the attached ppt file.>
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PXI-4461 is connected to an oscilloscope with BNC cable. 4461 uses the differencial mode (NOT pseudo-differential mode)
due to some reason. The positive signal from 4461 (i.e. the center core of BNC) is connected
to channel 1 of the oscilloscope, and the negative signal (i.e. the shield of BNC) is connected to
channel 2.
Then A sinewave which has the range from 0 to 2v and 1v offset, was generated in VB program.
Then it was applied to an oscilloscope. The channel 1 of oscilloscope showed a sinewave which has
the range from 0 to 1v with 0.5v offset, and the channel 2 showed a sine which has the range
from -1v to 0v with -0.5v offset.
For my application, the channel 1 is ok, but channel 2 should be shift up by 1v, basically the channel 2
should be a sine which has the range from 0v to +1v and +0.5v offset, and also its phase should lead
over 180 degree.
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