Power use of NI 6009- Can i combine it with other devices to one USB hub

[euanmcc]

I have developed a system which uses both a USB NI 6009 and a stimulator which is controlled by USB. Now my system would be much neater if I could use a USB hub to combine the DAQ and stimulator so I only have 1 wire going to the computer. However it appears the DAQ uses the whole 500mA avaliable from a single usb port. Is there any way I can get around this without connecting the hub to the mains. Is it possible to plug a usb hub into 2 usb ports to get 1A of power?

Thanks

[SnowMule]

Got some other source of power in there?  Either a 5V or 12V supply?

It's possible to plug the thing into two USB ports... but if you're taking up two ports anyways, why not just use one cable per device?  Certainly easier to deal with electrically.

I'm a big fan of and highly recommend these Startech hubs. Can feed it 7-24V DC on the terminal block, already has mounting ears, and it comes with a DIN-rail mounting kit.  Better hub too, saw errors in my equipment drop dramatically after I replaced the cheapo hubs I was using with these.

[taper]

I've seen devices before that use extra USB plugs for power draw.  Dirty little secret though is some computers split the 500mA power rail between multiple physical ports.  I wouldn't mess with it.  Powered hubs are pretty cheap.  You do need power from somewhere.  I know solar and battery powered hubs are commercially available if mains isn't.

[euanmcc]

Yeah were hoping to use it on a hospital ward so mains power isnt always avaliable or is already used up by other equipment. The use of 2 ports does seem worthless as i would have 2 lines anyway. Are the battery usb hubs reliable, as I cant afford for it to run out of steam during a test.

[SnowMule]

Put a big enough battery in there and it should run the equipment for days.  Downside to that is size and weight.  Put a battery tender on the battery and plug it in overnight to recharge/maintain the battery.

I use that startech hub I linked earlier to charge cameras, GPS, phone, ipod, etc off my motorcycle battery; or put a cig lighter plug on it and use it in my truck or trailer. 

No reason you couldn't use a differential input on the DAQ to measure and report the battery voltage.

(I have a big 125 A-H deep-cycle battery in my trailer, that alone will run the furnace overnight.  I've used this battery with a 200W inverter to run laptops, soldering irons, etc where there isn't a convienent 120V supply and I didn't want to drag my generator around.)

But yes... sounds like the bottom line is that you'll need more power to the equipment.

[taper]

Just to check, this isn't part of a life-critical system in the hospital, right?  That would bring in a whole new set of requirements.

How long would this need to run at a time?  If it's more than a few hours I'd just bite the bullet and find a plug-in, unless there's a special need like it being moved from room to room.

[euanmcc]

Its not life critical and would need to be used for around 1 hour at a time. It also needs to be portable as the same system will be used for different patients on the same day. I think im just going to bite the bullet and use 2 usb ports and cable tie the 2 wires together.