Please set like this   ./cgminer --bmsc-options 115200:1 --bmsc-voltage 0755 --bmsc-freq 0782
The voltage is too low, should at least 0725(turn to Readme)
For the issue about mining multiple U3 in the same cgminer, please connect the USB cable of each U3 into the same PC, or use the same USB hub, connected and run cgminer. Please noted that connection order must be - plug one side of 12V AC/DC power brick into U3, and plug the other side into AC input. Then, connect U3 and the computer via the USB line.

Hi, only with the option "Advanced Setting" in your miner status, you can adjust the voltage and frequency. Go to the Miner Configuration tab and in the Advanced Settings tab you will find the chip operating frequency and voltage set as default 225M and 0725-which means 0.725volts. You can select the voltage value from the pull-down menu, however you should modify the chip operating voltage by yourself as per the testing results. And the voltage and frequency should match in a proper way, otherwise, the miner will probably run in a abnormal status.

2 @ 2.55