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Handshaking p r o t o c o l
x-on/x-off Protocol
X-on/X-off protocol is a system in which the printer
transmits a code to the computer to indicate that it
cannot accept more data, and a second code when it is
once again ready. This protocol can be performed under
either RS232C or 20 mA Current Loop signal levels.
The C82302*/C82304* interface board sends an X-on
<11>
when it is ready to receive data, and an X-
code
H
<13>H
off
when
be transmitted from the TXD ten&al
Note
X-on/X-off protocol cannot be performed when the
buffer
operation
is still possible.
After the X-on flag has been set, data can be accepted up
to the maximum capacity of the buffer.
Transmit timing of X-off signal
l
The X-off signal is transmitted when the vacant area
for bytes in the buffer drops to 512 or 16 bytes
(selectable with DIP switch 2-6).
l
Data can be sent to the printer even after the X-Off
signal is transmitted as long as sufficient room for
data remains in the buffer.
ted data exceeds the vacant area in the buffer, it will
be discarded. X-off character will be transmitted
again when the remaining buffer capacity is actually
0 bytes. At the same time, BS code
character
it is busy. The X-On/X-off
is disabled. But the DTR flag protocol
will be sent to the printer.
<2F> H
at
if the transmit-
However,
<08>H
14
may
Signals
and "/"
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