SignalExpress

NI-USB 6210 Analog Output

Hi, I have a relatively simple setup consisting of flow sensors of which I am having trouble getting accurate analog output. I was wondering if anyone could help me out.

I have a couple of SMC PFMV505-1 flow sensors plugged into an mDAQ NI-USB 6210 in two different ways:

(I) SMC PFMV505-1 flow sensor --> PFMV3M display --> Analog output (1-5V, linear) into NI-USB 6210 box

(II) SMC PFMV505-1 flow sensor --> Analog output (1-5V) into NI-USB 6210 box

Except from this difference they are all wired in the same way and grounded. The flow sensors are serially connected to a pump where the pump is turned on. Once the flow is turned on, while the flow sensors with configuration (I) (red and white signal) show accurate values, (II) configuration sensors (green signal) show an oscillating value, where the signal goes outside the measurement range (<1V and >5V). (light blue is a sensor whose analog output is not plugged in, not relevant)

However, if I take a multimeter and measure the output value, the green output pins show a stable signal of 2.8V or so. It seems that the signal is not translated correctly at the NI box. In SignalExpress I am using signal input range 1-5V, scaled units: Volts, Terminal Configuration: Differential, No scaling, Continuous sample acquisition @ 285mHz.