SerialPortFR.readContinues

Read data while available by parts, sleep between checks.

Sleep time calculates from baud rate and count of bits in one byte.

---|-----|-----|------------|-----|------------> t
 call    |     |            |     |
readAll  |     |            |     |
   |     |     |            |     |
   |     |<---------data receive---------->|
   |     |=== =====   ======|     |   |== =|
   |     |     |  |   |     |     |
   |<-timeout->|  |   |     |     |
   |     |<-1->|  |<2>|     |<-3->|
   |     |                  |     |
   |     |<---readedData--->|     |
   |                            return
   |<------readAll work time----->|

(1) if readedData.length > 0 then continue reading
    else throw TimeoutException
(2) silent time, if silent < frameGap then continue reading
(3) else if silent > frameGap then stop reading
    and return readedData

Params: buf = buffer for reading startTimeout = timeout for first byte recive frameGap = detect new data frame by silence period

Returns: slice of buf with readed data

Throws: PortClosedException ReadException TimeoutException

See_Also: SerialPort.read