How to use HX85BA sensors with NI DAQ system?

[BBalmforth]

Hello,

I'm trying to connect two Omega HX85BA humidity sensors to my NI DAQ system. The sensors detect humidity, barometric pressure, and temperature, using three 0 to 10 Vdc positive outputs @ 10 mA max, with one output common wire. I have a SCXI 1000 chassis with two SCXI 1100 cards, one 1102B and one 1102. The 1102 card is using a SCXI 1303 terminal block, while the other three cards use 1300s. The system will use mostly thermocouples for temperature measurements, but there will be other types of sensors, such as the two HX85BAs.

The product manual for the HX85BAs is not very clear on how to connect the sensor to the system. The terminal blocks each have 32 channels with positive and negative screw terminals, so do I connect the three positive outputs from the sensor to individual channels, with the output common connected to each channel? Will this setup work with the SCXI cards I have, or will I need to purchase different cards? The system will be expanded to include at least 4 more cards in a separate SCXI 1000 chassis, so it is not a problem to purchase different components to fit the HX85BAs.

Thanks in advance! 

[SunainaK · Accepted solution]

Hi BBalmforth,

You can connect the sensor to TB 1300 of the SCXI 1100. Connect the positive output to CH+ and connect CH- to CHSGND. The output common wire should be connected to GND.

[BBalmforth]

When connecting the output common wire to GND, do you mean CHSGND on the 1100?

Thanks

[SunainaK]

Hi BBalmforth,

The CH- does not actually need to be grounded, since differential mode is not being used. Also, I did mean CHSGND for the output common wire.