Pressure Transducer Voltage Measurement Labview and DAQ 6281

[lstraughn]

Hello,

I am trying to use the National Insturments USB-6281 DAQ with a pressure transducer.  I have the transducer's excitation pins connected to a DC power supply which provides the 5 to 8 V required for the transducer.  I have the output,(+) and (-), wires connected to the DAQ at AI-0 and AI-GND.  When I utilize the DAQ assistant in LabView to read the voltage given from the transducer and display it on a numeric indicator, I only get a reading that starts at approximately zero and then slowly climbs without any correlation to the pressure provided to the transducer.  I have connected the transducers output wires to a multimeter and have got readings in milivolts, so it seems as thought the transducer and the wire connections are correct.  I don't know why I am not getting the proper readings from my DAQ to the LabView interface.  Please help if you can.

[Henrik_Volkers]

For the DAQ the input seems to be floating. Try adding a 1Meg resitor from AI- to AGND.

Have a look at the DAQ user manual for more details. You need to provide a input BIAS current path.