Hi, I have a USB-6002 DAQ card that I am trying to use to read an analog 0-10 V signal for pressure from a Vaisala PTB barometer. The barometer is sending out about 3.5 volts when read with a volt meter but the DAQ card says that it is reading about 9.6 VDC. I have tried reading both AI0 channel as well as differential to eleminate the potiential for ground differences as I am also using the AO channels for contol of other equipment. Just as soon as I touch my volt meter to the screw terminals on the DAQ card, it jumps down to the 3.5 volts that I am reading with the volt meter. The cable is not shielded but it is only about 5 feet long and is not running by any power lines which should be inducing any other signals. Do I need a resistor or cap in there to filter things out and if so, how would I go about sizing that or is there something else I should look at? I am using NIMax to read the voltages for now but when I use the Labview drivers, I get similar results.
Thanks,
Carl