USB Multifunction DAQ 6009 supply voltage

[siryu00]

Hi all, I have a USB DAQ 6009 that I am going to use for some lab experiments. I have a few pressure sensors that need a 5V excitation voltage supplied to them. I know that USB is 5V, and that you can draw from this 5V on one of the terminals, but I was wondering if anybody can vouch for the stability of that 5V? For example, the max pressure I will read is somewhere like 0.4kPa on a 6kPa max sensor, and it outputs 0-4.5V. Just wondering if I am likely to encounter any major fluctuations at all, or will connecting it to the DAQ 5V terminal be fine?

On a similar note I also have a load cell and an amplifier, which is going to be weighing individual carbon fibres during an experiment, so that will have it's own power supply because the accuracy is paramount.

[santo_13]

The 5V on the DAQ 6009 terminal comes from the USB port you connect it to. Now, those are USB2.0 which means you're limited to 500mA maximum which will be the sum of current required by DAQ 6009 to function and anything else you connect to the 5V terminal.

So, your question for the stability of 5V supply is directly the same as the port on PC or Laptop you connect it to. In general, I would not recommend using that 5V unless you are confident that your devices consume less than 100mA.

Edit: You can use up to 200mA as described in the pinout - https://www.ni.com/documentation/en/multifunction-io-device/latest/usb-6009/pinout/