November 1985
National Instruments
xon Change Serial Port XON/XOFF Protocol
xon:
Syntax:
Purpose:
Remarks:
Serial Port function
xon
You use
xon
at the beginning of your program to
configure the GPIB-MAC to communicate over the serial
port using the same
protocol as your
Macintosh.
The argument
booltx
specifies whether to enable the
protocol when sending data out on the
serial port. If the argument
booltx
is a 1, the
MAC monitors its serial receive buffer for
characters as it sends data over the serial port. If it
receives the
character (decimal 19 or
it
will immediately stop sending data. When it receives the
XON character (decimal 17 or
it begins
sending data again.
If you want to send a data string that may contain a
or
you must disable
booltx.
The
argument
boolrx
specifies whether to enable the
protocol when receiving data over the serial
port. If the argument
boolrx
is a 1, and the
MAC is receiving data over the serial port, it sends
over the serial port (if its serial receive buffer is
almost full). This tells the sender to stop sending data.
When the GPIB-MAC serial port receive buffer has
room to safely receive more bytes, the GPIB-MAC
sends XON over the serial port. This tells the sender to
begin sending data again.
You should use
when you are transferring
large amounts of data at a high baud rates. Without it,
you are in danger of
the GPIB-MAC
internal buffer or your Macintosh’s internal buffer.
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SECTION FOUR FUNCTIONS
