Handshaking Protocol - Epson C82305 Series User Manual

Handshaking protocol

DTR and X-on/X-off handshaking protocols can be
performed under either RS-232D or 20mA Current Loop
transmission.
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.
The C82305* /C82306* interface card sends an
X-on < 11
> H
an X-off < 13 >
may be transmitted from the TXD terminal at RS-232D
signal levels, or through the TTY-TXD terminal at 20
mA Current Loop levels.
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
The X-off signal is transmitted when the vacant area
in the buffer drops below the specified value
(typically 256 bytes; refer to your printer manual).
• Data transfer after X-off signal
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. However, if the
transmitted data exceeds the vacant area in the
buffer, it will be discarded.
code when it is ready to receive data, and
when it is busy. The X-on/X-off signals
H
14