Seiko FB-900 - Manual (Page 172)

● Serial interface
[CD (Carrier detect)]
This signal indicates whether the modem is connected
with the communication line. If data is sent to the printer
when this signal is active, the data is processed as valid
data. Data received when this signal is inactive is
ignored as invalid data.
By default, this signal is not used, and all data sent by the
computer is processed as valid data (i.e., the default
setting causes the same operation as when the CD signal
is active). Whether or not to use this signal for control is
selected in the
EXTENDED SETUP MODE .
[TXD (Transmit data)]
Serial output data.
X-ON, X-OFF and ACK signals are output.
The data format is the same as the received data format.
[RTS (Request to send)]
Always held active (space).
[SRTS]
This signal indicates that the printer is ready or busy.
OFF : Indicates that the printer is busy and printer is in
the offline state. Data transmission to the printer is
disabled.
ON : Indicates that the printer is ready and data can be
transmitted to the printer.
This signal is always ON when X-ON/X-OFF(
Ι
)or(
Π
)or
the ETX/ACK protocol is selected.
[DTR (Data terminal ready)]
This signal indicates that the printer is ready or busy.
OFF: Indicates that the printer is busy and printer is in the
offline state. Data transmission to the printer is
disabled.
ON: Indicates that the printer is ready and data can be
transmitted to the printer.
This signal is always ON when X-ON/X-OFF (I) or (II) or
the ETX/ACK protocol is selected.
7-7 — 7. Interface specifications —
See page 3-51.
Output signals from the printer