Power to USB Devices

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Level 8

37,591 points

Power to USB Devices

My rMBP will recognize and utilize both the Apple USB Superdrive, and a Pioneer BDR-XD05W, as such laptops have extra power via the USB port. My new Mac Pro will only recognize the Pioneer (which is USB3 compatible) via the USB2 on the connected TBolt Apple display (which is where I have regularly used the Apple drive, it being only rated for USB2.)

Are none of the onboard nMP USB ports capable of providing the needed power? Guess I will be getting a Pioneer power adaptor.

Ernie

Posted on Jul 11, 2014 9:12 AM

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Answer 1

Ernie Stamper Author

Level 8

37,591 points

Jul 15, 2014 8:22 AM in response to Ernie Stamper

After consulting a Genius at the Apple Store, where I was told the ports on the new Mac Pro should provide the needed power, proceeded to make other tests to see when and if it would be recognized.

I disconnected every USB device from the nMP, and then connected the Pioneer drive to various of the USB ports that should provide USB3. The device was now recognized on all of them. I then reconnected a powered USB3 drive I am using routinely, and then two other cables not active at the moment. Recognition of the Pioneer was not disturbed by this. I will have to experiment in time to see what if any activity can change this.

I find the document linked below confusing as to possible sequencing issues with USB connections:

Apple Computers and Displays: Powering peripherals through USB

Ernie

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Answer 2

Jul 15, 2014 8:51 AM in response to Ernie Stamper

This paragraph (from the article you cited) causes Users the most trouble. The amount of power NOT supplied during sleep can cause high-powered devices to disconnect or stop working entirely. For best reliability of certain external devices (like rotating Disk Drives and full-sized DVD Readers) consider an external power adapter.

Your Apple computer or display must be powered on and must be awake. If your Apple computer or display is asleep, all ports will provide their normal maximum [i.e., 500mA] output. If your Apple computer or display is powered off, no power will be provided.

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Answer 3

Ernie Stamper Author

Level 8

37,591 points

Jul 15, 2014 9:25 AM in response to Grant Bennet-Alder

Not sure how to apply that to my experience?

Ernie

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Answer 4

Jul 15, 2014 9:38 AM in response to Ernie Stamper

Are none of the onboard nMP USB ports capable of providing the needed power?

NOT if the Mac goes to sleep. Many Users have their Macs, especially notebook Macs, set to sleep on a very short idle time. Then the power supplied drops from a generous 1100mA to 500mA and external devices may not continue to function.

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