cDAQ USB dc voltage source

[falkpl]

I have implemented a DAQ system using cDaq and some modules to read some TCs and Pressures.  This all works well but the pressure gauges need a 24V power source (only a few mA current).  I was surprised to realize that the chassy has no DC out even though it takes a 30V in to power it.  Is the some easy method of getting the 24V from the usb cDAQ chassy or is there a good module to add so I will not need an external power source.  I am trying to keep the setup of this system very portable and easy to manage so avoiding a second power source is the goal.  Any ideas will be appreciated.

Paul

[TheWoost]

Hi Paul,

Unfortunately there is no way to tap into the main power rail of the cDAQ chassis.  The only modules available for sourcing high voltages are the NI 9472 Digital Output Module and NI 9481 Relay Module; however, these modules do require an external power supply to provide the required voltage level.  More information can be found about these modules at the following links:
NI 9472
NI 9481

Regards,
Andrew W
National Instruments

[Chris_Rake]

Another option is to get a replacement power connector and splice the power going to the chassis. 

[falkpl]

Thanks for the answers.  I will most likely just use the 9472 relay module.  Is is inexpensive and I will be deploying several systems. 

Paul 

[KyleBryson]

Paul,

Keep in mind that the 9472 doesn't supply the power, it requires an external supply of the voltage you desire.  Not sure if that meets your application or not, but wanted to make sure that was clear.

Regards,

Kyle

[falkpl]

Requires an external source of power? is this not from the USB chassy? or do I need another power source which means that I am back to square 1.  The description sounds like it wil source upto 750 mA 24V per channel.  Did I miss something?

Paul

[Chris_Rake]

Some external modules, like the 9472, require a separate power supply.  Check out page 7 of the 9472 manual http://www.ni.com/pdf/manuals/373509d.pdf.  There are several reasons for this, including the need for users to be able to control the supply voltage for their application (in the cast of the 9472 anywhere between 6V-30V).

[falkpl]

The need for an external power supply is not very clear in the description of the 9472 device.  So is there a way of sourcing power through a different module?  I am a little frustrated since I have upgraded(?) a fieldpoint system with this new technology only to find out that the usq day doesnt have a clear way of providing power to my pressure sensors.  This should be easy but I still have no solution.

[Chris_Rake]

I/O Modules are limited in the amount of power they can pull from the Chassis, so any significant sourcing needs will have to be supplied by an external supply.  Can you splice the power at the input?

[falkpl]

I need vary little power, it is for a few (1-2 maybe as many as 4) Pressure gauges which need 24V (10-30V will work) but only a few mA.  I didnt want to have to splice the power cord but is there a cleaner method like pulling the voltage off one of the back plane pins?  I am not an EE, most electronics have been self taught (I am a Comp. Sci guy), so any help is good for me.

Paul F