def read_sb_data(self):
buf = self.sbdataq<EOL>self.sbdataq = '<STR_LIT>'<EOL>return buf<EOL>
Return any data available in the SB ... SE queue.

        Return '' if no SB ... SE available. Should only be called
        after seeing a SB or SE command. When a new SB command is
        found, old unread SB data will be discarded. Don't block.