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• Transmit timing
of
the X-on signal
The X-on signal
is
transmitted
when the power
is
first
turned on, and when the vacant area
in
the buffer
is
greater
than
the preset value of the buffer recovery
timing. Refer to Table 12 for information on flag
set/reset
conditions.
Figure
3.
X-on/X-off
timing
X-ON
X-OFF X-OFF
X-ON
POWER
ON
Buffer
Buffer
Buffer
capacity
capacity: 512
capacity
specified with
or 16 bytes
0 byte
DIP
switches
3-2
and
3-3.
DTR
protocol
This interface card also provides for DTR handshaking
protocol using either RS-232D, RS-422A, or Current-
Loop signal levels.
Under this system, when the
printer
is
turned on the
DTR
enters the SPACE state, meaning that
data
entry
is
enabled. When the
rate
of
data
reception
is
greater than
that
of printing, the buffer gradually fills up. Once the
vacant
area
for
transmitted
bytes drops to flag set level,
the DTR sets the status flag to prohibit
further
data
entry. This flag
is
output through the DTR (pin No.
20)
under RS-232D signal levels, through the TRA and TRB
(pin No. 11,
13)
under RS-422A signal levels, and through
the TTY-TXD (pin No.
17)
under Current-Loop levels.
18