Voltage Offset for the NI-6115/6120 Using the +/- 42 Volt Analog Input Voltage RangeHardware: Multifunction DAQ (MIO)>>S Series>>PCI-6115, Multifunction DAQ (MIO)>>S Series>>PCI-6120, Multifunction DAQ (MIO), Multifunction DAQ (MIO)>>S Series>>PXI-6115, Multifunction DAQ (MIO)>>S Series>>PXI-6120, Multifunction DAQ (MIO)>>S Series>>PCI-6111, Multifunction DAQ (MIO)>>S Series>>PCI-6110
Problem: When I acquire data using my NI-6120 card using the DAQmx 8.0 driver, I am receiving a large voltage offset using the +/- 42 volts input voltage range. When I input a smaller signal and use the +/- 20 volt input range, the measured signal is correct. Why can't I acquire a signal using the +/- 42 volt range with my DAQ card? Solution: The DAQmx 8.0 driver scales the voltage incorrectly for the +/- 42 volts input voltage range for the 6110, 6111, 6115 and 6120 devices. To correct the voltage offset, you can scale the measurement in software as a work-around.
From the DAQmx Read.vi, select Unscaled >> 16-Bit Signed Integer from the drop down menu. Since the PCI-6120 has a 16-bit resolution, the N equals 65536. The attached program 6120 Scaling on 42V Range.vi acquires an analog input signal and scales the data in LabVIEW. NOTE: The work-around provides a temporary solution until the next DAQmx driver is released. Related Links: Product Manuals: NI 6115/6120 User Manual (May 2003 ) Product Manuals: S Series Help (February 2005 ) Attachments: 
Report Date: 01/17/2006 Last Updated: 01/18/2006 Document ID: 3TGFOVQP |
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