Ports on the powerbraille?

[Paul Migliorelli (+1 3 0 3 5 4 3 2 3 1 1)]

Hi all.  Not having ever gotten any docs for my powerbraille 80, I'm 
curious about the serial ports and things on the back.  Obviously I have 1 
going to the pc for brltty, and on the pc, I have another for speech.  Can 
you, for instance, use the other serial on the powerbraille for something 
else?  Like plugging in a braille lite for use with minicom?  How is this 
powerbraille extra serial port addressed?  Thanks much.