Will any NI boards output analog current form -20 to 20mA?

[bcrox42]

I have a need to drive a hydraulic servo valve (torque motor) that requires +/- mA current.  Are there any NI boards that are capable of this output based on a PID control input? Or will I require external hardware? Thanks.

[Daniel_H1]

Hi bcrox42,

What are the voltage requirements of your output? Are you interested in controlling an analog voltage output that is capable of providing up to 20mA or are do you want to be able to specifically control the current? Also, what kind of form factor are you looking for (PCI, USB, etc.)?

A good place to start looking would be to go to https://www.ni.com/en-us/shop/category/multifunction-io.html, and you can filter the results using the options on the left side. Something to keep in mind is that you can increase the current output capabilities by connecting output channels in parallel, as in this KnowledgeBase article. Note that the PCI-6704 referenced in that article is a voltage and current output card that can supply 20mA per channel, which may be useful for you.

Regards,

Daniel H.

[bcrox42]

I want to specifically control the current. I have spent a lot of time on the NI web site searching but cannot find any cards that have a bipolar current output. I would be using a PXI platform.

[AnalogKid2DigitalMan]

Here is one method of external hardware if you have a DAQ with a +/-10V output, it will convert to +/-20mA. Note the 1KHz bandwidth if this is too narrow for you.

There are many other manufactures of such devices.

http://www.dataforth.com/device.view.aspx?deviceid=331

-AK2DM 

[Daniel_H1]

Hi bcrox42,

If you want to have bipolar current-source capability, the PXI-4130 would do the job but it is a bit overkill. If you know the load you are driving, you could use one of our voltage output devices, such as the PXI-6229, with the analog output channels in parallel to be able to handle +/-20 mA. Either of these should work, but external hardware such as what AK2DM mentioned would be able to convert any voltage output to a current source. It will depend on what is best for your application.

Regards,

Daniel H.