ammeter module with computer link

I'm trying to find an ammeter which I can put in front of my computer's power supply which the computer can then read from (usb or serial). I've googled around and cant find much (including here on the forums). The main requirement besides having a computer interface is that it consume as little power as possible.

The reason for low power usage is I plan on leaving the computer running 24/7. The computer itself only draws about 3 watts (pandaboard).

I dont mind if the ammeter is powered off the computer (like via usb), but the circuit must remain closed even if its off. Otherwise the computer cant power on until ammeter is on, and ammeter cant power on until computer is on :-)


So, anyone know of such a device?

Thanks

You could try a resistor and read the voltage across it.

Any ammeter will pass the current through as they are low impedance and in series with the load - think of them as being like a fuse - ie, a low resistance.