I use a non-self-powered USB modem device for a solutions I provide to multiple customers, and very often I encounter a problem in which the devices stops working due to many reasons, one of which I suspect is insufficient USB power, but can't confirm. I could purchase a powered USB hub which I do sometimes, but the problem bugs me because I can't confirm that power is the problem and got to make trips to the customer's office at my own expense.
I've read the question How do you check how much power a USB port can deliver?, and followed the instructions in the answers.
The device I'm using is Sierra Wireless GL6110 USB modem. The vendor specification (see spec link below) says that the modem can draw up to 400mA max. Under Device Manager -> Generic USB Hub -> Power Tab, it says that the modem is drawing 20mA, which I believe is lower than the actual maximum. It also says that each port can draw up to 500mA.
I believe that the information provided under Power tab is not sufficient for me to gauge whether the system can provide enough power for my modem device because:
Firstly, even though the hub will provide up to 500mA per port, this is shared across multiple ports and there may not be enough power to provide 500mA for every single port.
Secondly, the power required by a device as indicated in Under Device Manager -> Generic USB Hub -> Power Tab, may not be accurate in the first place, and it is only a power required figure and not the actual power drawn.
So to solve my problem, I'm trying to find out if there a way for me to detect ACTUAL maximum power that can be supplied to a USB hub? What I intend to do is to activate all the USB devices connected to the system, e.g. if it is a USB speakers, I would turn on the speaks at full volume, and then measure the maximum power a port can deliver using some instrument or software.