Why CGMINER detects 9 known USB devices but only use 8

[hlbcal]

I connect 9 sets of AntMiner U3 to RaspBerry running CGMINERR via a powered USB hub.

The strange thing is, also CGMINER detects 9 USB devices, but only 8 devices are working. Pls advice what is actually going on?

CGMINER shows

"9 total known USB devices."
Hotplug interval: 5
8 USB devices, 8enabled, 0 desiabled, 0 zombie"

Thanks very much.

[elysimai]

explain more?!

[sobe-it]

You may need a 2nd hub, sometimes the pi can be funny with certain hubs or how many devices you can use with the hub. Do you power the pi off the hub or it has its own wall plug? If you power it from the hub, you may be pulling too much power from the hub to use the last miner.

Try unplugging all the miners but one and add 1 at a time, this will help rule out a bad miner or hub.  See if it finds them and they start to hash after each one you plug in. This way if you get to 8 plugged in with 8 hashing then the 9th wont hash, unplug one the others and plug in the 9th one in its place. If this works its the hub, if one don't hash before you get to the 8th its either an issue with the miner, usb cable or power cable.