4-20mA output signal to a DAQ USB-6009

[NicoVari]

Hi,

I have a pressure sensor with an output signal of 4-20mA, it is a 2 pin wiring setup. I would like to connect this sensor into the USB-6009 DAQ that measures from 0-5V. 

I know that the current needs to be converted to voltage with a 250 ohms resistor. Now, the problem arises when I try to connect the converted signal into the DAQ, I don't know if the wiring is not correct or what is going on. I use LabVIEW to display the signal in my computer. Another question in this matter is that what type of signal should I consider once I have the current converted?

Thanks

[dsasorin]

NicoVari,

The 250 ohm resistor is well choosed.

250 ohm * 0.02 A = 5 V max. Your signal is dc voltage. How did you connect it ?  You may want to consider differential schematic. Also, connect the negative wire to AIGND directly.

Check your manual DAQ.

[Lewis_G]

Hi NicoVari,

Using the DAQmx Create Channel VI, you can select an Analog Current Input.  You can then specify the shunt resistor your have used (Ohm).  You can then use the DAQmx Read VI to read the current.

What do you mean by "what type of signal should I consider once I have the current converted?" ? 

There is information about Measuring and Generating Current HERE.

There is an example on how to input a single Current reading on an  Analog Input Channel HERE.

There is an example on how to Continuously Acquire 0-20mA Current Samples- Software Timed HERE.

Let me know how you get on and if you have any more questions

Kind Regards