Epson 8900 Series - Manual (Page 206)

Serial Interface Connector
The serial communication interface transfers either 7-bit or 8-bit
character information in an asynchronous, bit-serial format. This
format is useful for transferring data over long distance lines via data
communication devices such as modems, but it can also be used to
transfer data directly between the host and the printer. The following
table lists the serial interface signals.
Serial Interface Signals
Signal Name EIA CCITT Pin Source
PG Protective ground AA 101 1
TD Transmit data BA 103 2 Printer
RD Receive data BB 104 3 Host
RTS Request to send CA 105 4 Printer
CTS Clear to send CB 106 5 Host
DSR Data set ready CC 107 6 Host
SG Signal ground AB 102 7
DCD Data carrier detect CF 109 8 Host
R/B Ready/busy — — 11 Printer
DTR Data terminal ready CD 108.2 20 Printer
Interface Connection
You can connect your printer to the host computer either directly via
an interface cable or through a system of modems and telephone lines
with an interface cable at each end of the system. The setup menu
structure provides settings (DIRECT CONNECT and MODEM
CONNECT) for each of these choices.
Communication Interfaces 10-15