So i have a bealge bone black with a 4.3 LCD cape running on debian. I also have a usb hub with 4 output. I currently use 3 of these output (wifi dongle, usb key and a prolific usb to DB9 serial adapter).
The serial adapter is here to read some values from an industrial scale.
Here is the problem. if the BBB is connected to a computer via the mini usb port, everything run well. (with an without a 2.5 amp on the power barrel.)
The second that i disconnect the BBB from the computer, the serial adapter will only receive 0xff caracter. Iv’e tried on others computer with DB9 connector to exclude the scale from the equation.
I have no clue and I can’t leave a computer connecter to the BBB just to get the serial adapter happy…
ps. I have 3 different serial adapter and same result for all. Also 3 different usb hub.
Thanks in advance