read_serial — Read from a serial device.
read_serial( : : SerialHandle, NumCharacters : Data)
read_serial tries to read NumCharacters from the
serial device given in SerialHandle. The read characters
are returned in Data as a tuple of integers. This allows
to read NUL characters, which would otherwise be interpreted as the
end of a string. If the timeout of the serial device has been set
to a value greater than 0 with set_serial_param,
read_serial waits at most as long for the arrival of the
first character as indicated by the timeout. Otherwise, the
operator returns immediately. In any case, the number of characters
available at the time of return are passed back to the caller, i.e.,
fewer characters than requested can be returned. This can be
checked by the length of the tuple Data.
SerialHandle (input_control) serial → (handle)
Serial interface handle.
NumCharacters (input_control) integer → (integer)
Number of characters to read.
Default: 1
Suggested values: 1, 2, 3, 4, 5, 10, 20, 40, 100
Data (output_control) integer(-array) → (integer)
Read characters (as tuple of integers).
If the parameters are correct and the read from the device was
successful, the operator read_serial returns the value 2 (
H_MSG_TRUE)
.
Otherwise an exception is raised.
Foundation