Can a SCXI 1102B with a 1303 block have some channels reading voltage signals and others reading current signals at the same time?

[BBalmforth]

Hello,

I am trying to use two Omega HX85BA humidity sensors and two FCI mass flow meters in a flow loop experiment. The humidity sensors have three 0-10V outputs while the flow meters have two 4-20mA outputs. Can I wire all four sensors to the same SCXI 1303 terminal block and read all the signals in the same VI? the block is connected to a SCXI 1102B card and a NI PCI 6052E DAQ card.

Thanks in advance!

[Izzzzz · Accepted solution]

Hello BBalmforth,

Yes it can. Although you will need external shunt resistors (I recommend precision resistors for better accuracy) for the Current Signals. The SCXI 1102B is indirectly measuring current by measuring the voltage drop across the resistor. The picture below describes the Current connection scheme as well as how this will look in LabVIEW and the DAQ assistant.

Wiring Scheme 

LabVIEW

DAQ Assistant 

Regards,

Izzy O.

Applications Engineer

National Instruments

ni.com/support  

[BBalmforth]

Hi Izzy,

Thanks for the help. What size resistors should I use for the 4-20 mA signals?

Thanks,

-BBalmforth

[Izzzzz]

I would recommend a 249Ohm resistor which is the default shunt resistor value when you create a current task via the DAQ assistant or the DAQmx Create Virtual Channel (Current Instance).

Best Regards,

Izzy O.
Applications Engineer
National Instruments
ni.com/support